diff options
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 7698 |
1 files changed, 7698 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c new file mode 100644 index 000000000..37288a7f0 --- /dev/null +++ b/mm/hugetlb.c @@ -0,0 +1,7698 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Generic hugetlb support. + * (C) Nadia Yvette Chambers, April 2004 + */ +#include <linux/list.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/seq_file.h> +#include <linux/sysctl.h> +#include <linux/highmem.h> +#include <linux/mmu_notifier.h> +#include <linux/nodemask.h> +#include <linux/pagemap.h> +#include <linux/mempolicy.h> +#include <linux/compiler.h> +#include <linux/cpuset.h> +#include <linux/mutex.h> +#include <linux/memblock.h> +#include <linux/sysfs.h> +#include <linux/slab.h> +#include <linux/sched/mm.h> +#include <linux/mmdebug.h> +#include <linux/sched/signal.h> +#include <linux/rmap.h> +#include <linux/string_helpers.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/jhash.h> +#include <linux/numa.h> +#include <linux/llist.h> +#include <linux/cma.h> +#include <linux/migrate.h> +#include <linux/nospec.h> +#include <linux/delayacct.h> +#include <linux/memory.h> + +#include <asm/page.h> +#include <asm/pgalloc.h> +#include <asm/tlb.h> + +#include <linux/io.h> +#include <linux/hugetlb.h> +#include <linux/hugetlb_cgroup.h> +#include <linux/node.h> +#include <linux/page_owner.h> +#include "internal.h" +#include "hugetlb_vmemmap.h" + +int hugetlb_max_hstate __read_mostly; +unsigned int default_hstate_idx; +struct hstate hstates[HUGE_MAX_HSTATE]; + +#ifdef CONFIG_CMA +static struct cma *hugetlb_cma[MAX_NUMNODES]; +static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata; +static bool hugetlb_cma_page(struct page *page, unsigned int order) +{ + return cma_pages_valid(hugetlb_cma[page_to_nid(page)], page, + 1 << order); +} +#else +static bool hugetlb_cma_page(struct page *page, unsigned int order) +{ + return false; +} +#endif +static unsigned long hugetlb_cma_size __initdata; + +__initdata LIST_HEAD(huge_boot_pages); + +/* for command line parsing */ +static struct hstate * __initdata parsed_hstate; +static unsigned long __initdata default_hstate_max_huge_pages; +static bool __initdata parsed_valid_hugepagesz = true; +static bool __initdata parsed_default_hugepagesz; +static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata; + +/* + * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, + * free_huge_pages, and surplus_huge_pages. + */ +DEFINE_SPINLOCK(hugetlb_lock); + +/* + * Serializes faults on the same logical page. This is used to + * prevent spurious OOMs when the hugepage pool is fully utilized. + */ +static int num_fault_mutexes; +struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp; + +/* Forward declaration */ +static int hugetlb_acct_memory(struct hstate *h, long delta); +static void hugetlb_vma_lock_free(struct vm_area_struct *vma); +static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma); +static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma); +static void hugetlb_unshare_pmds(struct vm_area_struct *vma, + unsigned long start, unsigned long end); +static struct resv_map *vma_resv_map(struct vm_area_struct *vma); + +static inline bool subpool_is_free(struct hugepage_subpool *spool) +{ + if (spool->count) + return false; + if (spool->max_hpages != -1) + return spool->used_hpages == 0; + if (spool->min_hpages != -1) + return spool->rsv_hpages == spool->min_hpages; + + return true; +} + +static inline void unlock_or_release_subpool(struct hugepage_subpool *spool, + unsigned long irq_flags) +{ + spin_unlock_irqrestore(&spool->lock, irq_flags); + + /* If no pages are used, and no other handles to the subpool + * remain, give up any reservations based on minimum size and + * free the subpool */ + if (subpool_is_free(spool)) { + if (spool->min_hpages != -1) + hugetlb_acct_memory(spool->hstate, + -spool->min_hpages); + kfree(spool); + } +} + +struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages, + long min_hpages) +{ + struct hugepage_subpool *spool; + + spool = kzalloc(sizeof(*spool), GFP_KERNEL); + if (!spool) + return NULL; + + spin_lock_init(&spool->lock); + spool->count = 1; + spool->max_hpages = max_hpages; + spool->hstate = h; + spool->min_hpages = min_hpages; + + if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) { + kfree(spool); + return NULL; + } + spool->rsv_hpages = min_hpages; + + return spool; +} + +void hugepage_put_subpool(struct hugepage_subpool *spool) +{ + unsigned long flags; + + spin_lock_irqsave(&spool->lock, flags); + BUG_ON(!spool->count); + spool->count--; + unlock_or_release_subpool(spool, flags); +} + +/* + * Subpool accounting for allocating and reserving pages. + * Return -ENOMEM if there are not enough resources to satisfy the + * request. Otherwise, return the number of pages by which the + * global pools must be adjusted (upward). The returned value may + * only be different than the passed value (delta) in the case where + * a subpool minimum size must be maintained. + */ +static long hugepage_subpool_get_pages(struct hugepage_subpool *spool, + long delta) +{ + long ret = delta; + + if (!spool) + return ret; + + spin_lock_irq(&spool->lock); + + if (spool->max_hpages != -1) { /* maximum size accounting */ + if ((spool->used_hpages + delta) <= spool->max_hpages) + spool->used_hpages += delta; + else { + ret = -ENOMEM; + goto unlock_ret; + } + } + + /* minimum size accounting */ + if (spool->min_hpages != -1 && spool->rsv_hpages) { + if (delta > spool->rsv_hpages) { + /* + * Asking for more reserves than those already taken on + * behalf of subpool. Return difference. + */ + ret = delta - spool->rsv_hpages; + spool->rsv_hpages = 0; + } else { + ret = 0; /* reserves already accounted for */ + spool->rsv_hpages -= delta; + } + } + +unlock_ret: + spin_unlock_irq(&spool->lock); + return ret; +} + +/* + * Subpool accounting for freeing and unreserving pages. + * Return the number of global page reservations that must be dropped. + * The return value may only be different than the passed value (delta) + * in the case where a subpool minimum size must be maintained. + */ +static long hugepage_subpool_put_pages(struct hugepage_subpool *spool, + long delta) +{ + long ret = delta; + unsigned long flags; + + if (!spool) + return delta; + + spin_lock_irqsave(&spool->lock, flags); + + if (spool->max_hpages != -1) /* maximum size accounting */ + spool->used_hpages -= delta; + + /* minimum size accounting */ + if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) { + if (spool->rsv_hpages + delta <= spool->min_hpages) + ret = 0; + else + ret = spool->rsv_hpages + delta - spool->min_hpages; + + spool->rsv_hpages += delta; + if (spool->rsv_hpages > spool->min_hpages) + spool->rsv_hpages = spool->min_hpages; + } + + /* + * If hugetlbfs_put_super couldn't free spool due to an outstanding + * quota reference, free it now. + */ + unlock_or_release_subpool(spool, flags); + + return ret; +} + +static inline struct hugepage_subpool *subpool_inode(struct inode *inode) +{ + return HUGETLBFS_SB(inode->i_sb)->spool; +} + +static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma) +{ + return subpool_inode(file_inode(vma->vm_file)); +} + +/* + * hugetlb vma_lock helper routines + */ +static bool __vma_shareable_lock(struct vm_area_struct *vma) +{ + return vma->vm_flags & (VM_MAYSHARE | VM_SHARED) && + vma->vm_private_data; +} + +void hugetlb_vma_lock_read(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + down_read(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + down_read(&resv_map->rw_sema); + } +} + +void hugetlb_vma_unlock_read(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + up_read(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + up_read(&resv_map->rw_sema); + } +} + +void hugetlb_vma_lock_write(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + down_write(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + down_write(&resv_map->rw_sema); + } +} + +void hugetlb_vma_unlock_write(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + up_write(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + up_write(&resv_map->rw_sema); + } +} + +int hugetlb_vma_trylock_write(struct vm_area_struct *vma) +{ + + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + return down_write_trylock(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + return down_write_trylock(&resv_map->rw_sema); + } + + return 1; +} + +void hugetlb_vma_assert_locked(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + lockdep_assert_held(&vma_lock->rw_sema); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + lockdep_assert_held(&resv_map->rw_sema); + } +} + +void hugetlb_vma_lock_release(struct kref *kref) +{ + struct hugetlb_vma_lock *vma_lock = container_of(kref, + struct hugetlb_vma_lock, refs); + + kfree(vma_lock); +} + +static void __hugetlb_vma_unlock_write_put(struct hugetlb_vma_lock *vma_lock) +{ + struct vm_area_struct *vma = vma_lock->vma; + + /* + * vma_lock structure may or not be released as a result of put, + * it certainly will no longer be attached to vma so clear pointer. + * Semaphore synchronizes access to vma_lock->vma field. + */ + vma_lock->vma = NULL; + vma->vm_private_data = NULL; + up_write(&vma_lock->rw_sema); + kref_put(&vma_lock->refs, hugetlb_vma_lock_release); +} + +static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma) +{ + if (__vma_shareable_lock(vma)) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + __hugetlb_vma_unlock_write_put(vma_lock); + } else if (__vma_private_lock(vma)) { + struct resv_map *resv_map = vma_resv_map(vma); + + /* no free for anon vmas, but still need to unlock */ + up_write(&resv_map->rw_sema); + } +} + +static void hugetlb_vma_lock_free(struct vm_area_struct *vma) +{ + /* + * Only present in sharable vmas. + */ + if (!vma || !__vma_shareable_lock(vma)) + return; + + if (vma->vm_private_data) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + down_write(&vma_lock->rw_sema); + __hugetlb_vma_unlock_write_put(vma_lock); + } +} + +static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma) +{ + struct hugetlb_vma_lock *vma_lock; + + /* Only establish in (flags) sharable vmas */ + if (!vma || !(vma->vm_flags & VM_MAYSHARE)) + return; + + /* Should never get here with non-NULL vm_private_data */ + if (vma->vm_private_data) + return; + + vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL); + if (!vma_lock) { + /* + * If we can not allocate structure, then vma can not + * participate in pmd sharing. This is only a possible + * performance enhancement and memory saving issue. + * However, the lock is also used to synchronize page + * faults with truncation. If the lock is not present, + * unlikely races could leave pages in a file past i_size + * until the file is removed. Warn in the unlikely case of + * allocation failure. + */ + pr_warn_once("HugeTLB: unable to allocate vma specific lock\n"); + return; + } + + kref_init(&vma_lock->refs); + init_rwsem(&vma_lock->rw_sema); + vma_lock->vma = vma; + vma->vm_private_data = vma_lock; +} + +/* Helper that removes a struct file_region from the resv_map cache and returns + * it for use. + */ +static struct file_region * +get_file_region_entry_from_cache(struct resv_map *resv, long from, long to) +{ + struct file_region *nrg; + + VM_BUG_ON(resv->region_cache_count <= 0); + + resv->region_cache_count--; + nrg = list_first_entry(&resv->region_cache, struct file_region, link); + list_del(&nrg->link); + + nrg->from = from; + nrg->to = to; + + return nrg; +} + +static void copy_hugetlb_cgroup_uncharge_info(struct file_region *nrg, + struct file_region *rg) +{ +#ifdef CONFIG_CGROUP_HUGETLB + nrg->reservation_counter = rg->reservation_counter; + nrg->css = rg->css; + if (rg->css) + css_get(rg->css); +#endif +} + +/* Helper that records hugetlb_cgroup uncharge info. */ +static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg, + struct hstate *h, + struct resv_map *resv, + struct file_region *nrg) +{ +#ifdef CONFIG_CGROUP_HUGETLB + if (h_cg) { + nrg->reservation_counter = + &h_cg->rsvd_hugepage[hstate_index(h)]; + nrg->css = &h_cg->css; + /* + * The caller will hold exactly one h_cg->css reference for the + * whole contiguous reservation region. But this area might be + * scattered when there are already some file_regions reside in + * it. As a result, many file_regions may share only one css + * reference. In order to ensure that one file_region must hold + * exactly one h_cg->css reference, we should do css_get for + * each file_region and leave the reference held by caller + * untouched. + */ + css_get(&h_cg->css); + if (!resv->pages_per_hpage) + resv->pages_per_hpage = pages_per_huge_page(h); + /* pages_per_hpage should be the same for all entries in + * a resv_map. + */ + VM_BUG_ON(resv->pages_per_hpage != pages_per_huge_page(h)); + } else { + nrg->reservation_counter = NULL; + nrg->css = NULL; + } +#endif +} + +static void put_uncharge_info(struct file_region *rg) +{ +#ifdef CONFIG_CGROUP_HUGETLB + if (rg->css) + css_put(rg->css); +#endif +} + +static bool has_same_uncharge_info(struct file_region *rg, + struct file_region *org) +{ +#ifdef CONFIG_CGROUP_HUGETLB + return rg->reservation_counter == org->reservation_counter && + rg->css == org->css; + +#else + return true; +#endif +} + +static void coalesce_file_region(struct resv_map *resv, struct file_region *rg) +{ + struct file_region *nrg, *prg; + + prg = list_prev_entry(rg, link); + if (&prg->link != &resv->regions && prg->to == rg->from && + has_same_uncharge_info(prg, rg)) { + prg->to = rg->to; + + list_del(&rg->link); + put_uncharge_info(rg); + kfree(rg); + + rg = prg; + } + + nrg = list_next_entry(rg, link); + if (&nrg->link != &resv->regions && nrg->from == rg->to && + has_same_uncharge_info(nrg, rg)) { + nrg->from = rg->from; + + list_del(&rg->link); + put_uncharge_info(rg); + kfree(rg); + } +} + +static inline long +hugetlb_resv_map_add(struct resv_map *map, struct list_head *rg, long from, + long to, struct hstate *h, struct hugetlb_cgroup *cg, + long *regions_needed) +{ + struct file_region *nrg; + + if (!regions_needed) { + nrg = get_file_region_entry_from_cache(map, from, to); + record_hugetlb_cgroup_uncharge_info(cg, h, map, nrg); + list_add(&nrg->link, rg); + coalesce_file_region(map, nrg); + } else + *regions_needed += 1; + + return to - from; +} + +/* + * Must be called with resv->lock held. + * + * Calling this with regions_needed != NULL will count the number of pages + * to be added but will not modify the linked list. And regions_needed will + * indicate the number of file_regions needed in the cache to carry out to add + * the regions for this range. + */ +static long add_reservation_in_range(struct resv_map *resv, long f, long t, + struct hugetlb_cgroup *h_cg, + struct hstate *h, long *regions_needed) +{ + long add = 0; + struct list_head *head = &resv->regions; + long last_accounted_offset = f; + struct file_region *iter, *trg = NULL; + struct list_head *rg = NULL; + + if (regions_needed) + *regions_needed = 0; + + /* In this loop, we essentially handle an entry for the range + * [last_accounted_offset, iter->from), at every iteration, with some + * bounds checking. + */ + list_for_each_entry_safe(iter, trg, head, link) { + /* Skip irrelevant regions that start before our range. */ + if (iter->from < f) { + /* If this region ends after the last accounted offset, + * then we need to update last_accounted_offset. + */ + if (iter->to > last_accounted_offset) + last_accounted_offset = iter->to; + continue; + } + + /* When we find a region that starts beyond our range, we've + * finished. + */ + if (iter->from >= t) { + rg = iter->link.prev; + break; + } + + /* Add an entry for last_accounted_offset -> iter->from, and + * update last_accounted_offset. + */ + if (iter->from > last_accounted_offset) + add += hugetlb_resv_map_add(resv, iter->link.prev, + last_accounted_offset, + iter->from, h, h_cg, + regions_needed); + + last_accounted_offset = iter->to; + } + + /* Handle the case where our range extends beyond + * last_accounted_offset. + */ + if (!rg) + rg = head->prev; + if (last_accounted_offset < t) + add += hugetlb_resv_map_add(resv, rg, last_accounted_offset, + t, h, h_cg, regions_needed); + + return add; +} + +/* Must be called with resv->lock acquired. Will drop lock to allocate entries. + */ +static int allocate_file_region_entries(struct resv_map *resv, + int regions_needed) + __must_hold(&resv->lock) +{ + LIST_HEAD(allocated_regions); + int to_allocate = 0, i = 0; + struct file_region *trg = NULL, *rg = NULL; + + VM_BUG_ON(regions_needed < 0); + + /* + * Check for sufficient descriptors in the cache to accommodate + * the number of in progress add operations plus regions_needed. + * + * This is a while loop because when we drop the lock, some other call + * to region_add or region_del may have consumed some region_entries, + * so we keep looping here until we finally have enough entries for + * (adds_in_progress + regions_needed). + */ + while (resv->region_cache_count < + (resv->adds_in_progress + regions_needed)) { + to_allocate = resv->adds_in_progress + regions_needed - + resv->region_cache_count; + + /* At this point, we should have enough entries in the cache + * for all the existing adds_in_progress. We should only be + * needing to allocate for regions_needed. + */ + VM_BUG_ON(resv->region_cache_count < resv->adds_in_progress); + + spin_unlock(&resv->lock); + for (i = 0; i < to_allocate; i++) { + trg = kmalloc(sizeof(*trg), GFP_KERNEL); + if (!trg) + goto out_of_memory; + list_add(&trg->link, &allocated_regions); + } + + spin_lock(&resv->lock); + + list_splice(&allocated_regions, &resv->region_cache); + resv->region_cache_count += to_allocate; + } + + return 0; + +out_of_memory: + list_for_each_entry_safe(rg, trg, &allocated_regions, link) { + list_del(&rg->link); + kfree(rg); + } + return -ENOMEM; +} + +/* + * Add the huge page range represented by [f, t) to the reserve + * map. Regions will be taken from the cache to fill in this range. + * Sufficient regions should exist in the cache due to the previous + * call to region_chg with the same range, but in some cases the cache will not + * have sufficient entries due to races with other code doing region_add or + * region_del. The extra needed entries will be allocated. + * + * regions_needed is the out value provided by a previous call to region_chg. + * + * Return the number of new huge pages added to the map. This number is greater + * than or equal to zero. If file_region entries needed to be allocated for + * this operation and we were not able to allocate, it returns -ENOMEM. + * region_add of regions of length 1 never allocate file_regions and cannot + * fail; region_chg will always allocate at least 1 entry and a region_add for + * 1 page will only require at most 1 entry. + */ +static long region_add(struct resv_map *resv, long f, long t, + long in_regions_needed, struct hstate *h, + struct hugetlb_cgroup *h_cg) +{ + long add = 0, actual_regions_needed = 0; + + spin_lock(&resv->lock); +retry: + + /* Count how many regions are actually needed to execute this add. */ + add_reservation_in_range(resv, f, t, NULL, NULL, + &actual_regions_needed); + + /* + * Check for sufficient descriptors in the cache to accommodate + * this add operation. Note that actual_regions_needed may be greater + * than in_regions_needed, as the resv_map may have been modified since + * the region_chg call. In this case, we need to make sure that we + * allocate extra entries, such that we have enough for all the + * existing adds_in_progress, plus the excess needed for this + * operation. + */ + if (actual_regions_needed > in_regions_needed && + resv->region_cache_count < + resv->adds_in_progress + + (actual_regions_needed - in_regions_needed)) { + /* region_add operation of range 1 should never need to + * allocate file_region entries. + */ + VM_BUG_ON(t - f <= 1); + + if (allocate_file_region_entries( + resv, actual_regions_needed - in_regions_needed)) { + return -ENOMEM; + } + + goto retry; + } + + add = add_reservation_in_range(resv, f, t, h_cg, h, NULL); + + resv->adds_in_progress -= in_regions_needed; + + spin_unlock(&resv->lock); + return add; +} + +/* + * Examine the existing reserve map and determine how many + * huge pages in the specified range [f, t) are NOT currently + * represented. This routine is called before a subsequent + * call to region_add that will actually modify the reserve + * map to add the specified range [f, t). region_chg does + * not change the number of huge pages represented by the + * map. A number of new file_region structures is added to the cache as a + * placeholder, for the subsequent region_add call to use. At least 1 + * file_region structure is added. + * + * out_regions_needed is the number of regions added to the + * resv->adds_in_progress. This value needs to be provided to a follow up call + * to region_add or region_abort for proper accounting. + * + * Returns the number of huge pages that need to be added to the existing + * reservation map for the range [f, t). This number is greater or equal to + * zero. -ENOMEM is returned if a new file_region structure or cache entry + * is needed and can not be allocated. + */ +static long region_chg(struct resv_map *resv, long f, long t, + long *out_regions_needed) +{ + long chg = 0; + + spin_lock(&resv->lock); + + /* Count how many hugepages in this range are NOT represented. */ + chg = add_reservation_in_range(resv, f, t, NULL, NULL, + out_regions_needed); + + if (*out_regions_needed == 0) + *out_regions_needed = 1; + + if (allocate_file_region_entries(resv, *out_regions_needed)) + return -ENOMEM; + + resv->adds_in_progress += *out_regions_needed; + + spin_unlock(&resv->lock); + return chg; +} + +/* + * Abort the in progress add operation. The adds_in_progress field + * of the resv_map keeps track of the operations in progress between + * calls to region_chg and region_add. Operations are sometimes + * aborted after the call to region_chg. In such cases, region_abort + * is called to decrement the adds_in_progress counter. regions_needed + * is the value returned by the region_chg call, it is used to decrement + * the adds_in_progress counter. + * + * NOTE: The range arguments [f, t) are not needed or used in this + * routine. They are kept to make reading the calling code easier as + * arguments will match the associated region_chg call. + */ +static void region_abort(struct resv_map *resv, long f, long t, + long regions_needed) +{ + spin_lock(&resv->lock); + VM_BUG_ON(!resv->region_cache_count); + resv->adds_in_progress -= regions_needed; + spin_unlock(&resv->lock); +} + +/* + * Delete the specified range [f, t) from the reserve map. If the + * t parameter is LONG_MAX, this indicates that ALL regions after f + * should be deleted. Locate the regions which intersect [f, t) + * and either trim, delete or split the existing regions. + * + * Returns the number of huge pages deleted from the reserve map. + * In the normal case, the return value is zero or more. In the + * case where a region must be split, a new region descriptor must + * be allocated. If the allocation fails, -ENOMEM will be returned. + * NOTE: If the parameter t == LONG_MAX, then we will never split + * a region and possibly return -ENOMEM. Callers specifying + * t == LONG_MAX do not need to check for -ENOMEM error. + */ +static long region_del(struct resv_map *resv, long f, long t) +{ + struct list_head *head = &resv->regions; + struct file_region *rg, *trg; + struct file_region *nrg = NULL; + long del = 0; + +retry: + spin_lock(&resv->lock); + list_for_each_entry_safe(rg, trg, head, link) { + /* + * Skip regions before the range to be deleted. file_region + * ranges are normally of the form [from, to). However, there + * may be a "placeholder" entry in the map which is of the form + * (from, to) with from == to. Check for placeholder entries + * at the beginning of the range to be deleted. + */ + if (rg->to <= f && (rg->to != rg->from || rg->to != f)) + continue; + + if (rg->from >= t) + break; + + if (f > rg->from && t < rg->to) { /* Must split region */ + /* + * Check for an entry in the cache before dropping + * lock and attempting allocation. + */ + if (!nrg && + resv->region_cache_count > resv->adds_in_progress) { + nrg = list_first_entry(&resv->region_cache, + struct file_region, + link); + list_del(&nrg->link); + resv->region_cache_count--; + } + + if (!nrg) { + spin_unlock(&resv->lock); + nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); + if (!nrg) + return -ENOMEM; + goto retry; + } + + del += t - f; + hugetlb_cgroup_uncharge_file_region( + resv, rg, t - f, false); + + /* New entry for end of split region */ + nrg->from = t; + nrg->to = rg->to; + + copy_hugetlb_cgroup_uncharge_info(nrg, rg); + + INIT_LIST_HEAD(&nrg->link); + + /* Original entry is trimmed */ + rg->to = f; + + list_add(&nrg->link, &rg->link); + nrg = NULL; + break; + } + + if (f <= rg->from && t >= rg->to) { /* Remove entire region */ + del += rg->to - rg->from; + hugetlb_cgroup_uncharge_file_region(resv, rg, + rg->to - rg->from, true); + list_del(&rg->link); + kfree(rg); + continue; + } + + if (f <= rg->from) { /* Trim beginning of region */ + hugetlb_cgroup_uncharge_file_region(resv, rg, + t - rg->from, false); + + del += t - rg->from; + rg->from = t; + } else { /* Trim end of region */ + hugetlb_cgroup_uncharge_file_region(resv, rg, + rg->to - f, false); + + del += rg->to - f; + rg->to = f; + } + } + + spin_unlock(&resv->lock); + kfree(nrg); + return del; +} + +/* + * A rare out of memory error was encountered which prevented removal of + * the reserve map region for a page. The huge page itself was free'ed + * and removed from the page cache. This routine will adjust the subpool + * usage count, and the global reserve count if needed. By incrementing + * these counts, the reserve map entry which could not be deleted will + * appear as a "reserved" entry instead of simply dangling with incorrect + * counts. + */ +void hugetlb_fix_reserve_counts(struct inode *inode) +{ + struct hugepage_subpool *spool = subpool_inode(inode); + long rsv_adjust; + bool reserved = false; + + rsv_adjust = hugepage_subpool_get_pages(spool, 1); + if (rsv_adjust > 0) { + struct hstate *h = hstate_inode(inode); + + if (!hugetlb_acct_memory(h, 1)) + reserved = true; + } else if (!rsv_adjust) { + reserved = true; + } + + if (!reserved) + pr_warn("hugetlb: Huge Page Reserved count may go negative.\n"); +} + +/* + * Count and return the number of huge pages in the reserve map + * that intersect with the range [f, t). + */ +static long region_count(struct resv_map *resv, long f, long t) +{ + struct list_head *head = &resv->regions; + struct file_region *rg; + long chg = 0; + + spin_lock(&resv->lock); + /* Locate each segment we overlap with, and count that overlap. */ + list_for_each_entry(rg, head, link) { + long seg_from; + long seg_to; + + if (rg->to <= f) + continue; + if (rg->from >= t) + break; + + seg_from = max(rg->from, f); + seg_to = min(rg->to, t); + + chg += seg_to - seg_from; + } + spin_unlock(&resv->lock); + + return chg; +} + +/* + * Convert the address within this vma to the page offset within + * the mapping, in pagecache page units; huge pages here. + */ +static pgoff_t vma_hugecache_offset(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + return ((address - vma->vm_start) >> huge_page_shift(h)) + + (vma->vm_pgoff >> huge_page_order(h)); +} + +pgoff_t linear_hugepage_index(struct vm_area_struct *vma, + unsigned long address) +{ + return vma_hugecache_offset(hstate_vma(vma), vma, address); +} +EXPORT_SYMBOL_GPL(linear_hugepage_index); + +/* + * Return the size of the pages allocated when backing a VMA. In the majority + * cases this will be same size as used by the page table entries. + */ +unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) +{ + if (vma->vm_ops && vma->vm_ops->pagesize) + return vma->vm_ops->pagesize(vma); + return PAGE_SIZE; +} +EXPORT_SYMBOL_GPL(vma_kernel_pagesize); + +/* + * Return the page size being used by the MMU to back a VMA. In the majority + * of cases, the page size used by the kernel matches the MMU size. On + * architectures where it differs, an architecture-specific 'strong' + * version of this symbol is required. + */ +__weak unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) +{ + return vma_kernel_pagesize(vma); +} + +/* + * Flags for MAP_PRIVATE reservations. These are stored in the bottom + * bits of the reservation map pointer, which are always clear due to + * alignment. + */ +#define HPAGE_RESV_OWNER (1UL << 0) +#define HPAGE_RESV_UNMAPPED (1UL << 1) +#define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) + +/* + * These helpers are used to track how many pages are reserved for + * faults in a MAP_PRIVATE mapping. Only the process that called mmap() + * is guaranteed to have their future faults succeed. + * + * With the exception of hugetlb_dup_vma_private() which is called at fork(), + * the reserve counters are updated with the hugetlb_lock held. It is safe + * to reset the VMA at fork() time as it is not in use yet and there is no + * chance of the global counters getting corrupted as a result of the values. + * + * The private mapping reservation is represented in a subtly different + * manner to a shared mapping. A shared mapping has a region map associated + * with the underlying file, this region map represents the backing file + * pages which have ever had a reservation assigned which this persists even + * after the page is instantiated. A private mapping has a region map + * associated with the original mmap which is attached to all VMAs which + * reference it, this region map represents those offsets which have consumed + * reservation ie. where pages have been instantiated. + */ +static unsigned long get_vma_private_data(struct vm_area_struct *vma) +{ + return (unsigned long)vma->vm_private_data; +} + +static void set_vma_private_data(struct vm_area_struct *vma, + unsigned long value) +{ + vma->vm_private_data = (void *)value; +} + +static void +resv_map_set_hugetlb_cgroup_uncharge_info(struct resv_map *resv_map, + struct hugetlb_cgroup *h_cg, + struct hstate *h) +{ +#ifdef CONFIG_CGROUP_HUGETLB + if (!h_cg || !h) { + resv_map->reservation_counter = NULL; + resv_map->pages_per_hpage = 0; + resv_map->css = NULL; + } else { + resv_map->reservation_counter = + &h_cg->rsvd_hugepage[hstate_index(h)]; + resv_map->pages_per_hpage = pages_per_huge_page(h); + resv_map->css = &h_cg->css; + } +#endif +} + +struct resv_map *resv_map_alloc(void) +{ + struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); + struct file_region *rg = kmalloc(sizeof(*rg), GFP_KERNEL); + + if (!resv_map || !rg) { + kfree(resv_map); + kfree(rg); + return NULL; + } + + kref_init(&resv_map->refs); + spin_lock_init(&resv_map->lock); + INIT_LIST_HEAD(&resv_map->regions); + init_rwsem(&resv_map->rw_sema); + + resv_map->adds_in_progress = 0; + /* + * Initialize these to 0. On shared mappings, 0's here indicate these + * fields don't do cgroup accounting. On private mappings, these will be + * re-initialized to the proper values, to indicate that hugetlb cgroup + * reservations are to be un-charged from here. + */ + resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, NULL, NULL); + + INIT_LIST_HEAD(&resv_map->region_cache); + list_add(&rg->link, &resv_map->region_cache); + resv_map->region_cache_count = 1; + + return resv_map; +} + +void resv_map_release(struct kref *ref) +{ + struct resv_map *resv_map = container_of(ref, struct resv_map, refs); + struct list_head *head = &resv_map->region_cache; + struct file_region *rg, *trg; + + /* Clear out any active regions before we release the map. */ + region_del(resv_map, 0, LONG_MAX); + + /* ... and any entries left in the cache */ + list_for_each_entry_safe(rg, trg, head, link) { + list_del(&rg->link); + kfree(rg); + } + + VM_BUG_ON(resv_map->adds_in_progress); + + kfree(resv_map); +} + +static inline struct resv_map *inode_resv_map(struct inode *inode) +{ + /* + * At inode evict time, i_mapping may not point to the original + * address space within the inode. This original address space + * contains the pointer to the resv_map. So, always use the + * address space embedded within the inode. + * The VERY common case is inode->mapping == &inode->i_data but, + * this may not be true for device special inodes. + */ + return (struct resv_map *)(&inode->i_data)->private_data; +} + +static struct resv_map *vma_resv_map(struct vm_area_struct *vma) +{ + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); + if (vma->vm_flags & VM_MAYSHARE) { + struct address_space *mapping = vma->vm_file->f_mapping; + struct inode *inode = mapping->host; + + return inode_resv_map(inode); + + } else { + return (struct resv_map *)(get_vma_private_data(vma) & + ~HPAGE_RESV_MASK); + } +} + +static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) +{ + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); + VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma); + + set_vma_private_data(vma, (unsigned long)map); +} + +static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) +{ + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); + VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma); + + set_vma_private_data(vma, get_vma_private_data(vma) | flags); +} + +static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) +{ + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); + + return (get_vma_private_data(vma) & flag) != 0; +} + +bool __vma_private_lock(struct vm_area_struct *vma) +{ + return !(vma->vm_flags & VM_MAYSHARE) && + get_vma_private_data(vma) & ~HPAGE_RESV_MASK && + is_vma_resv_set(vma, HPAGE_RESV_OWNER); +} + +void hugetlb_dup_vma_private(struct vm_area_struct *vma) +{ + VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); + /* + * Clear vm_private_data + * - For shared mappings this is a per-vma semaphore that may be + * allocated in a subsequent call to hugetlb_vm_op_open. + * Before clearing, make sure pointer is not associated with vma + * as this will leak the structure. This is the case when called + * via clear_vma_resv_huge_pages() and hugetlb_vm_op_open has already + * been called to allocate a new structure. + * - For MAP_PRIVATE mappings, this is the reserve map which does + * not apply to children. Faults generated by the children are + * not guaranteed to succeed, even if read-only. + */ + if (vma->vm_flags & VM_MAYSHARE) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + if (vma_lock && vma_lock->vma != vma) + vma->vm_private_data = NULL; + } else + vma->vm_private_data = NULL; +} + +/* + * Reset and decrement one ref on hugepage private reservation. + * Called with mm->mmap_sem writer semaphore held. + * This function should be only used by move_vma() and operate on + * same sized vma. It should never come here with last ref on the + * reservation. + */ +void clear_vma_resv_huge_pages(struct vm_area_struct *vma) +{ + /* + * Clear the old hugetlb private page reservation. + * It has already been transferred to new_vma. + * + * During a mremap() operation of a hugetlb vma we call move_vma() + * which copies vma into new_vma and unmaps vma. After the copy + * operation both new_vma and vma share a reference to the resv_map + * struct, and at that point vma is about to be unmapped. We don't + * want to return the reservation to the pool at unmap of vma because + * the reservation still lives on in new_vma, so simply decrement the + * ref here and remove the resv_map reference from this vma. + */ + struct resv_map *reservations = vma_resv_map(vma); + + if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + resv_map_put_hugetlb_cgroup_uncharge_info(reservations); + kref_put(&reservations->refs, resv_map_release); + } + + hugetlb_dup_vma_private(vma); +} + +/* Returns true if the VMA has associated reserve pages */ +static bool vma_has_reserves(struct vm_area_struct *vma, long chg) +{ + if (vma->vm_flags & VM_NORESERVE) { + /* + * This address is already reserved by other process(chg == 0), + * so, we should decrement reserved count. Without decrementing, + * reserve count remains after releasing inode, because this + * allocated page will go into page cache and is regarded as + * coming from reserved pool in releasing step. Currently, we + * don't have any other solution to deal with this situation + * properly, so add work-around here. + */ + if (vma->vm_flags & VM_MAYSHARE && chg == 0) + return true; + else + return false; + } + + /* Shared mappings always use reserves */ + if (vma->vm_flags & VM_MAYSHARE) { + /* + * We know VM_NORESERVE is not set. Therefore, there SHOULD + * be a region map for all pages. The only situation where + * there is no region map is if a hole was punched via + * fallocate. In this case, there really are no reserves to + * use. This situation is indicated if chg != 0. + */ + if (chg) + return false; + else + return true; + } + + /* + * Only the process that called mmap() has reserves for + * private mappings. + */ + if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + /* + * Like the shared case above, a hole punch or truncate + * could have been performed on the private mapping. + * Examine the value of chg to determine if reserves + * actually exist or were previously consumed. + * Very Subtle - The value of chg comes from a previous + * call to vma_needs_reserves(). The reserve map for + * private mappings has different (opposite) semantics + * than that of shared mappings. vma_needs_reserves() + * has already taken this difference in semantics into + * account. Therefore, the meaning of chg is the same + * as in the shared case above. Code could easily be + * combined, but keeping it separate draws attention to + * subtle differences. + */ + if (chg) + return false; + else + return true; + } + + return false; +} + +static void enqueue_huge_page(struct hstate *h, struct page *page) +{ + int nid = page_to_nid(page); + + lockdep_assert_held(&hugetlb_lock); + VM_BUG_ON_PAGE(page_count(page), page); + + list_move(&page->lru, &h->hugepage_freelists[nid]); + h->free_huge_pages++; + h->free_huge_pages_node[nid]++; + SetHPageFreed(page); +} + +static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid) +{ + struct page *page; + bool pin = !!(current->flags & PF_MEMALLOC_PIN); + + lockdep_assert_held(&hugetlb_lock); + list_for_each_entry(page, &h->hugepage_freelists[nid], lru) { + if (pin && !is_longterm_pinnable_page(page)) + continue; + + if (PageHWPoison(page)) + continue; + + list_move(&page->lru, &h->hugepage_activelist); + set_page_refcounted(page); + ClearHPageFreed(page); + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + return page; + } + + return NULL; +} + +static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid, + nodemask_t *nmask) +{ + unsigned int cpuset_mems_cookie; + struct zonelist *zonelist; + struct zone *zone; + struct zoneref *z; + int node = NUMA_NO_NODE; + + zonelist = node_zonelist(nid, gfp_mask); + +retry_cpuset: + cpuset_mems_cookie = read_mems_allowed_begin(); + for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) { + struct page *page; + + if (!cpuset_zone_allowed(zone, gfp_mask)) + continue; + /* + * no need to ask again on the same node. Pool is node rather than + * zone aware + */ + if (zone_to_nid(zone) == node) + continue; + node = zone_to_nid(zone); + + page = dequeue_huge_page_node_exact(h, node); + if (page) + return page; + } + if (unlikely(read_mems_allowed_retry(cpuset_mems_cookie))) + goto retry_cpuset; + + return NULL; +} + +static unsigned long available_huge_pages(struct hstate *h) +{ + return h->free_huge_pages - h->resv_huge_pages; +} + +static struct page *dequeue_huge_page_vma(struct hstate *h, + struct vm_area_struct *vma, + unsigned long address, int avoid_reserve, + long chg) +{ + struct page *page = NULL; + struct mempolicy *mpol; + gfp_t gfp_mask; + nodemask_t *nodemask; + int nid; + + /* + * A child process with MAP_PRIVATE mappings created by their parent + * have no page reserves. This check ensures that reservations are + * not "stolen". The child may still get SIGKILLed + */ + if (!vma_has_reserves(vma, chg) && !available_huge_pages(h)) + goto err; + + /* If reserves cannot be used, ensure enough pages are in the pool */ + if (avoid_reserve && !available_huge_pages(h)) + goto err; + + gfp_mask = htlb_alloc_mask(h); + nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask); + + if (mpol_is_preferred_many(mpol)) { + page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask); + + /* Fallback to all nodes if page==NULL */ + nodemask = NULL; + } + + if (!page) + page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask); + + if (page && !avoid_reserve && vma_has_reserves(vma, chg)) { + SetHPageRestoreReserve(page); + h->resv_huge_pages--; + } + + mpol_cond_put(mpol); + return page; + +err: + return NULL; +} + +/* + * common helper functions for hstate_next_node_to_{alloc|free}. + * We may have allocated or freed a huge page based on a different + * nodes_allowed previously, so h->next_node_to_{alloc|free} might + * be outside of *nodes_allowed. Ensure that we use an allowed + * node for alloc or free. + */ +static int next_node_allowed(int nid, nodemask_t *nodes_allowed) +{ + nid = next_node_in(nid, *nodes_allowed); + VM_BUG_ON(nid >= MAX_NUMNODES); + + return nid; +} + +static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) +{ + if (!node_isset(nid, *nodes_allowed)) + nid = next_node_allowed(nid, nodes_allowed); + return nid; +} + +/* + * returns the previously saved node ["this node"] from which to + * allocate a persistent huge page for the pool and advance the + * next node from which to allocate, handling wrap at end of node + * mask. + */ +static int hstate_next_node_to_alloc(struct hstate *h, + nodemask_t *nodes_allowed) +{ + int nid; + + VM_BUG_ON(!nodes_allowed); + + nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); + h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); + + return nid; +} + +/* + * helper for remove_pool_huge_page() - return the previously saved + * node ["this node"] from which to free a huge page. Advance the + * next node id whether or not we find a free huge page to free so + * that the next attempt to free addresses the next node. + */ +static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) +{ + int nid; + + VM_BUG_ON(!nodes_allowed); + + nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); + h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); + + return nid; +} + +#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \ + for (nr_nodes = nodes_weight(*mask); \ + nr_nodes > 0 && \ + ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \ + nr_nodes--) + +#define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \ + for (nr_nodes = nodes_weight(*mask); \ + nr_nodes > 0 && \ + ((node = hstate_next_node_to_free(hs, mask)) || 1); \ + nr_nodes--) + +/* used to demote non-gigantic_huge pages as well */ +static void __destroy_compound_gigantic_page(struct page *page, + unsigned int order, bool demote) +{ + int i; + int nr_pages = 1 << order; + struct page *p; + + atomic_set(compound_mapcount_ptr(page), 0); + atomic_set(compound_pincount_ptr(page), 0); + + for (i = 1; i < nr_pages; i++) { + p = nth_page(page, i); + p->mapping = NULL; + clear_compound_head(p); + if (!demote) + set_page_refcounted(p); + } + + set_compound_order(page, 0); +#ifdef CONFIG_64BIT + page[1].compound_nr = 0; +#endif + __ClearPageHead(page); +} + +static void destroy_compound_hugetlb_page_for_demote(struct page *page, + unsigned int order) +{ + __destroy_compound_gigantic_page(page, order, true); +} + +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE +static void destroy_compound_gigantic_page(struct page *page, + unsigned int order) +{ + __destroy_compound_gigantic_page(page, order, false); +} + +static void free_gigantic_page(struct page *page, unsigned int order) +{ + /* + * If the page isn't allocated using the cma allocator, + * cma_release() returns false. + */ +#ifdef CONFIG_CMA + if (cma_release(hugetlb_cma[page_to_nid(page)], page, 1 << order)) + return; +#endif + + free_contig_range(page_to_pfn(page), 1 << order); +} + +#ifdef CONFIG_CONTIG_ALLOC +static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask, + int nid, nodemask_t *nodemask) +{ + unsigned long nr_pages = pages_per_huge_page(h); + if (nid == NUMA_NO_NODE) + nid = numa_mem_id(); + +#ifdef CONFIG_CMA + { + struct page *page; + int node; + + if (hugetlb_cma[nid]) { + page = cma_alloc(hugetlb_cma[nid], nr_pages, + huge_page_order(h), true); + if (page) + return page; + } + + if (!(gfp_mask & __GFP_THISNODE)) { + for_each_node_mask(node, *nodemask) { + if (node == nid || !hugetlb_cma[node]) + continue; + + page = cma_alloc(hugetlb_cma[node], nr_pages, + huge_page_order(h), true); + if (page) + return page; + } + } + } +#endif + + return alloc_contig_pages(nr_pages, gfp_mask, nid, nodemask); +} + +#else /* !CONFIG_CONTIG_ALLOC */ +static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask, + int nid, nodemask_t *nodemask) +{ + return NULL; +} +#endif /* CONFIG_CONTIG_ALLOC */ + +#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */ +static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask, + int nid, nodemask_t *nodemask) +{ + return NULL; +} +static inline void free_gigantic_page(struct page *page, unsigned int order) { } +static inline void destroy_compound_gigantic_page(struct page *page, + unsigned int order) { } +#endif + +static inline void __clear_hugetlb_destructor(struct hstate *h, + struct page *page) +{ + lockdep_assert_held(&hugetlb_lock); + + /* + * Very subtle + * + * For non-gigantic pages set the destructor to the normal compound + * page dtor. This is needed in case someone takes an additional + * temporary ref to the page, and freeing is delayed until they drop + * their reference. + * + * For gigantic pages set the destructor to the null dtor. This + * destructor will never be called. Before freeing the gigantic + * page destroy_compound_gigantic_folio will turn the folio into a + * simple group of pages. After this the destructor does not + * apply. + * + */ + if (hstate_is_gigantic(h)) + set_compound_page_dtor(page, NULL_COMPOUND_DTOR); + else + set_compound_page_dtor(page, COMPOUND_PAGE_DTOR); +} + +/* + * Remove hugetlb page from lists. + * If vmemmap exists for the page, update dtor so that the page appears + * as just a compound page. Otherwise, wait until after allocating vmemmap + * to update dtor. + * + * A reference is held on the page, except in the case of demote. + * + * Must be called with hugetlb lock held. + */ +static void __remove_hugetlb_page(struct hstate *h, struct page *page, + bool adjust_surplus, + bool demote) +{ + int nid = page_to_nid(page); + + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page); + VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page); + + lockdep_assert_held(&hugetlb_lock); + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) + return; + + list_del(&page->lru); + + if (HPageFreed(page)) { + h->free_huge_pages--; + h->free_huge_pages_node[nid]--; + } + if (adjust_surplus) { + h->surplus_huge_pages--; + h->surplus_huge_pages_node[nid]--; + } + + /* + * We can only clear the hugetlb destructor after allocating vmemmap + * pages. Otherwise, someone (memory error handling) may try to write + * to tail struct pages. + */ + if (!HPageVmemmapOptimized(page)) + __clear_hugetlb_destructor(h, page); + + /* + * In the case of demote we do not ref count the page as it will soon + * be turned into a page of smaller size. + */ + if (!demote) + set_page_refcounted(page); + + h->nr_huge_pages--; + h->nr_huge_pages_node[nid]--; +} + +static void remove_hugetlb_page(struct hstate *h, struct page *page, + bool adjust_surplus) +{ + __remove_hugetlb_page(h, page, adjust_surplus, false); +} + +static void remove_hugetlb_page_for_demote(struct hstate *h, struct page *page, + bool adjust_surplus) +{ + __remove_hugetlb_page(h, page, adjust_surplus, true); +} + +static void add_hugetlb_page(struct hstate *h, struct page *page, + bool adjust_surplus) +{ + int zeroed; + int nid = page_to_nid(page); + + VM_BUG_ON_PAGE(!HPageVmemmapOptimized(page), page); + + lockdep_assert_held(&hugetlb_lock); + + INIT_LIST_HEAD(&page->lru); + h->nr_huge_pages++; + h->nr_huge_pages_node[nid]++; + + if (adjust_surplus) { + h->surplus_huge_pages++; + h->surplus_huge_pages_node[nid]++; + } + + set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); + set_page_private(page, 0); + /* + * We have to set HPageVmemmapOptimized again as above + * set_page_private(page, 0) cleared it. + */ + SetHPageVmemmapOptimized(page); + + /* + * This page is about to be managed by the hugetlb allocator and + * should have no users. Drop our reference, and check for others + * just in case. + */ + zeroed = put_page_testzero(page); + if (!zeroed) + /* + * It is VERY unlikely soneone else has taken a ref on + * the page. In this case, we simply return as the + * hugetlb destructor (free_huge_page) will be called + * when this other ref is dropped. + */ + return; + + arch_clear_hugepage_flags(page); + enqueue_huge_page(h, page); +} + +static void __update_and_free_page(struct hstate *h, struct page *page) +{ + int i; + struct page *subpage; + bool clear_dtor = HPageVmemmapOptimized(page); + + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) + return; + + /* + * If we don't know which subpages are hwpoisoned, we can't free + * the hugepage, so it's leaked intentionally. + */ + if (HPageRawHwpUnreliable(page)) + return; + + if (hugetlb_vmemmap_restore(h, page)) { + spin_lock_irq(&hugetlb_lock); + /* + * If we cannot allocate vmemmap pages, just refuse to free the + * page and put the page back on the hugetlb free list and treat + * as a surplus page. + */ + add_hugetlb_page(h, page, true); + spin_unlock_irq(&hugetlb_lock); + return; + } + + /* + * Move PageHWPoison flag from head page to the raw error pages, + * which makes any healthy subpages reusable. + */ + if (unlikely(PageHWPoison(page))) + hugetlb_clear_page_hwpoison(page); + + /* + * If vmemmap pages were allocated above, then we need to clear the + * hugetlb destructor under the hugetlb lock. + */ + if (clear_dtor) { + spin_lock_irq(&hugetlb_lock); + __clear_hugetlb_destructor(h, page); + spin_unlock_irq(&hugetlb_lock); + } + + for (i = 0; i < pages_per_huge_page(h); i++) { + subpage = nth_page(page, i); + subpage->flags &= ~(1 << PG_locked | 1 << PG_error | + 1 << PG_referenced | 1 << PG_dirty | + 1 << PG_active | 1 << PG_private | + 1 << PG_writeback); + } + + /* + * Non-gigantic pages demoted from CMA allocated gigantic pages + * need to be given back to CMA in free_gigantic_page. + */ + if (hstate_is_gigantic(h) || + hugetlb_cma_page(page, huge_page_order(h))) { + destroy_compound_gigantic_page(page, huge_page_order(h)); + free_gigantic_page(page, huge_page_order(h)); + } else { + __free_pages(page, huge_page_order(h)); + } +} + +/* + * As update_and_free_page() can be called under any context, so we cannot + * use GFP_KERNEL to allocate vmemmap pages. However, we can defer the + * actual freeing in a workqueue to prevent from using GFP_ATOMIC to allocate + * the vmemmap pages. + * + * free_hpage_workfn() locklessly retrieves the linked list of pages to be + * freed and frees them one-by-one. As the page->mapping pointer is going + * to be cleared in free_hpage_workfn() anyway, it is reused as the llist_node + * structure of a lockless linked list of huge pages to be freed. + */ +static LLIST_HEAD(hpage_freelist); + +static void free_hpage_workfn(struct work_struct *work) +{ + struct llist_node *node; + + node = llist_del_all(&hpage_freelist); + + while (node) { + struct page *page; + struct hstate *h; + + page = container_of((struct address_space **)node, + struct page, mapping); + node = node->next; + page->mapping = NULL; + /* + * The VM_BUG_ON_PAGE(!PageHuge(page), page) in page_hstate() + * is going to trigger because a previous call to + * remove_hugetlb_page() will set_compound_page_dtor(page, + * NULL_COMPOUND_DTOR), so do not use page_hstate() directly. + */ + h = size_to_hstate(page_size(page)); + + __update_and_free_page(h, page); + + cond_resched(); + } +} +static DECLARE_WORK(free_hpage_work, free_hpage_workfn); + +static inline void flush_free_hpage_work(struct hstate *h) +{ + if (hugetlb_vmemmap_optimizable(h)) + flush_work(&free_hpage_work); +} + +static void update_and_free_page(struct hstate *h, struct page *page, + bool atomic) +{ + if (!HPageVmemmapOptimized(page) || !atomic) { + __update_and_free_page(h, page); + return; + } + + /* + * Defer freeing to avoid using GFP_ATOMIC to allocate vmemmap pages. + * + * Only call schedule_work() if hpage_freelist is previously + * empty. Otherwise, schedule_work() had been called but the workfn + * hasn't retrieved the list yet. + */ + if (llist_add((struct llist_node *)&page->mapping, &hpage_freelist)) + schedule_work(&free_hpage_work); +} + +static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list) +{ + struct page *page, *t_page; + + list_for_each_entry_safe(page, t_page, list, lru) { + update_and_free_page(h, page, false); + cond_resched(); + } +} + +struct hstate *size_to_hstate(unsigned long size) +{ + struct hstate *h; + + for_each_hstate(h) { + if (huge_page_size(h) == size) + return h; + } + return NULL; +} + +void free_huge_page(struct page *page) +{ + /* + * Can't pass hstate in here because it is called from the + * compound page destructor. + */ + struct hstate *h = page_hstate(page); + int nid = page_to_nid(page); + struct hugepage_subpool *spool = hugetlb_page_subpool(page); + bool restore_reserve; + unsigned long flags; + + VM_BUG_ON_PAGE(page_count(page), page); + VM_BUG_ON_PAGE(page_mapcount(page), page); + + hugetlb_set_page_subpool(page, NULL); + if (PageAnon(page)) + __ClearPageAnonExclusive(page); + page->mapping = NULL; + restore_reserve = HPageRestoreReserve(page); + ClearHPageRestoreReserve(page); + + /* + * If HPageRestoreReserve was set on page, page allocation consumed a + * reservation. If the page was associated with a subpool, there + * would have been a page reserved in the subpool before allocation + * via hugepage_subpool_get_pages(). Since we are 'restoring' the + * reservation, do not call hugepage_subpool_put_pages() as this will + * remove the reserved page from the subpool. + */ + if (!restore_reserve) { + /* + * A return code of zero implies that the subpool will be + * under its minimum size if the reservation is not restored + * after page is free. Therefore, force restore_reserve + * operation. + */ + if (hugepage_subpool_put_pages(spool, 1) == 0) + restore_reserve = true; + } + + spin_lock_irqsave(&hugetlb_lock, flags); + ClearHPageMigratable(page); + hugetlb_cgroup_uncharge_page(hstate_index(h), + pages_per_huge_page(h), page); + hugetlb_cgroup_uncharge_page_rsvd(hstate_index(h), + pages_per_huge_page(h), page); + if (restore_reserve) + h->resv_huge_pages++; + + if (HPageTemporary(page)) { + remove_hugetlb_page(h, page, false); + spin_unlock_irqrestore(&hugetlb_lock, flags); + update_and_free_page(h, page, true); + } else if (h->surplus_huge_pages_node[nid]) { + /* remove the page from active list */ + remove_hugetlb_page(h, page, true); + spin_unlock_irqrestore(&hugetlb_lock, flags); + update_and_free_page(h, page, true); + } else { + arch_clear_hugepage_flags(page); + enqueue_huge_page(h, page); + spin_unlock_irqrestore(&hugetlb_lock, flags); + } +} + +/* + * Must be called with the hugetlb lock held + */ +static void __prep_account_new_huge_page(struct hstate *h, int nid) +{ + lockdep_assert_held(&hugetlb_lock); + h->nr_huge_pages++; + h->nr_huge_pages_node[nid]++; +} + +static void __prep_new_huge_page(struct hstate *h, struct page *page) +{ + hugetlb_vmemmap_optimize(h, page); + INIT_LIST_HEAD(&page->lru); + set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); + hugetlb_set_page_subpool(page, NULL); + set_hugetlb_cgroup(page, NULL); + set_hugetlb_cgroup_rsvd(page, NULL); +} + +static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) +{ + __prep_new_huge_page(h, page); + spin_lock_irq(&hugetlb_lock); + __prep_account_new_huge_page(h, nid); + spin_unlock_irq(&hugetlb_lock); +} + +static bool __prep_compound_gigantic_page(struct page *page, unsigned int order, + bool demote) +{ + int i, j; + int nr_pages = 1 << order; + struct page *p; + + /* we rely on prep_new_huge_page to set the destructor */ + set_compound_order(page, order); + __ClearPageReserved(page); + __SetPageHead(page); + for (i = 0; i < nr_pages; i++) { + p = nth_page(page, i); + + /* + * For gigantic hugepages allocated through bootmem at + * boot, it's safer to be consistent with the not-gigantic + * hugepages and clear the PG_reserved bit from all tail pages + * too. Otherwise drivers using get_user_pages() to access tail + * pages may get the reference counting wrong if they see + * PG_reserved set on a tail page (despite the head page not + * having PG_reserved set). Enforcing this consistency between + * head and tail pages allows drivers to optimize away a check + * on the head page when they need know if put_page() is needed + * after get_user_pages(). + */ + if (i != 0) /* head page cleared above */ + __ClearPageReserved(p); + /* + * Subtle and very unlikely + * + * Gigantic 'page allocators' such as memblock or cma will + * return a set of pages with each page ref counted. We need + * to turn this set of pages into a compound page with tail + * page ref counts set to zero. Code such as speculative page + * cache adding could take a ref on a 'to be' tail page. + * We need to respect any increased ref count, and only set + * the ref count to zero if count is currently 1. If count + * is not 1, we return an error. An error return indicates + * the set of pages can not be converted to a gigantic page. + * The caller who allocated the pages should then discard the + * pages using the appropriate free interface. + * + * In the case of demote, the ref count will be zero. + */ + if (!demote) { + if (!page_ref_freeze(p, 1)) { + pr_warn("HugeTLB page can not be used due to unexpected inflated ref count\n"); + goto out_error; + } + } else { + VM_BUG_ON_PAGE(page_count(p), p); + } + if (i != 0) + set_compound_head(p, page); + } + atomic_set(compound_mapcount_ptr(page), -1); + atomic_set(compound_pincount_ptr(page), 0); + return true; + +out_error: + /* undo page modifications made above */ + for (j = 0; j < i; j++) { + p = nth_page(page, j); + if (j != 0) + clear_compound_head(p); + set_page_refcounted(p); + } + /* need to clear PG_reserved on remaining tail pages */ + for (; j < nr_pages; j++) { + p = nth_page(page, j); + __ClearPageReserved(p); + } + set_compound_order(page, 0); +#ifdef CONFIG_64BIT + page[1].compound_nr = 0; +#endif + __ClearPageHead(page); + return false; +} + +static bool prep_compound_gigantic_page(struct page *page, unsigned int order) +{ + return __prep_compound_gigantic_page(page, order, false); +} + +static bool prep_compound_gigantic_page_for_demote(struct page *page, + unsigned int order) +{ + return __prep_compound_gigantic_page(page, order, true); +} + +/* + * PageHuge() only returns true for hugetlbfs pages, but not for normal or + * transparent huge pages. See the PageTransHuge() documentation for more + * details. + */ +int PageHuge(struct page *page) +{ + if (!PageCompound(page)) + return 0; + + page = compound_head(page); + return page[1].compound_dtor == HUGETLB_PAGE_DTOR; +} +EXPORT_SYMBOL_GPL(PageHuge); + +/* + * PageHeadHuge() only returns true for hugetlbfs head page, but not for + * normal or transparent huge pages. + */ +int PageHeadHuge(struct page *page_head) +{ + if (!PageHead(page_head)) + return 0; + + return page_head[1].compound_dtor == HUGETLB_PAGE_DTOR; +} +EXPORT_SYMBOL_GPL(PageHeadHuge); + +/* + * Find and lock address space (mapping) in write mode. + * + * Upon entry, the page is locked which means that page_mapping() is + * stable. Due to locking order, we can only trylock_write. If we can + * not get the lock, simply return NULL to caller. + */ +struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage) +{ + struct address_space *mapping = page_mapping(hpage); + + if (!mapping) + return mapping; + + if (i_mmap_trylock_write(mapping)) + return mapping; + + return NULL; +} + +pgoff_t hugetlb_basepage_index(struct page *page) +{ + struct page *page_head = compound_head(page); + pgoff_t index = page_index(page_head); + unsigned long compound_idx; + + if (compound_order(page_head) >= MAX_ORDER) + compound_idx = page_to_pfn(page) - page_to_pfn(page_head); + else + compound_idx = page - page_head; + + return (index << compound_order(page_head)) + compound_idx; +} + +static struct page *alloc_buddy_huge_page(struct hstate *h, + gfp_t gfp_mask, int nid, nodemask_t *nmask, + nodemask_t *node_alloc_noretry) +{ + int order = huge_page_order(h); + struct page *page; + bool alloc_try_hard = true; + bool retry = true; + + /* + * By default we always try hard to allocate the page with + * __GFP_RETRY_MAYFAIL flag. However, if we are allocating pages in + * a loop (to adjust global huge page counts) and previous allocation + * failed, do not continue to try hard on the same node. Use the + * node_alloc_noretry bitmap to manage this state information. + */ + if (node_alloc_noretry && node_isset(nid, *node_alloc_noretry)) + alloc_try_hard = false; + gfp_mask |= __GFP_COMP|__GFP_NOWARN; + if (alloc_try_hard) + gfp_mask |= __GFP_RETRY_MAYFAIL; + if (nid == NUMA_NO_NODE) + nid = numa_mem_id(); +retry: + page = __alloc_pages(gfp_mask, order, nid, nmask); + + /* Freeze head page */ + if (page && !page_ref_freeze(page, 1)) { + __free_pages(page, order); + if (retry) { /* retry once */ + retry = false; + goto retry; + } + /* WOW! twice in a row. */ + pr_warn("HugeTLB head page unexpected inflated ref count\n"); + page = NULL; + } + + if (page) + __count_vm_event(HTLB_BUDDY_PGALLOC); + else + __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); + + /* + * If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this + * indicates an overall state change. Clear bit so that we resume + * normal 'try hard' allocations. + */ + if (node_alloc_noretry && page && !alloc_try_hard) + node_clear(nid, *node_alloc_noretry); + + /* + * If we tried hard to get a page but failed, set bit so that + * subsequent attempts will not try as hard until there is an + * overall state change. + */ + if (node_alloc_noretry && !page && alloc_try_hard) + node_set(nid, *node_alloc_noretry); + + return page; +} + +/* + * Common helper to allocate a fresh hugetlb page. All specific allocators + * should use this function to get new hugetlb pages + * + * Note that returned page is 'frozen': ref count of head page and all tail + * pages is zero. + */ +static struct page *alloc_fresh_huge_page(struct hstate *h, + gfp_t gfp_mask, int nid, nodemask_t *nmask, + nodemask_t *node_alloc_noretry) +{ + struct page *page; + bool retry = false; + +retry: + if (hstate_is_gigantic(h)) + page = alloc_gigantic_page(h, gfp_mask, nid, nmask); + else + page = alloc_buddy_huge_page(h, gfp_mask, + nid, nmask, node_alloc_noretry); + if (!page) + return NULL; + + if (hstate_is_gigantic(h)) { + if (!prep_compound_gigantic_page(page, huge_page_order(h))) { + /* + * Rare failure to convert pages to compound page. + * Free pages and try again - ONCE! + */ + free_gigantic_page(page, huge_page_order(h)); + if (!retry) { + retry = true; + goto retry; + } + return NULL; + } + } + prep_new_huge_page(h, page, page_to_nid(page)); + + return page; +} + +/* + * Allocates a fresh page to the hugetlb allocator pool in the node interleaved + * manner. + */ +static int alloc_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, + nodemask_t *node_alloc_noretry) +{ + struct page *page; + int nr_nodes, node; + gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; + + for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { + page = alloc_fresh_huge_page(h, gfp_mask, node, nodes_allowed, + node_alloc_noretry); + if (page) + break; + } + + if (!page) + return 0; + + free_huge_page(page); /* free it into the hugepage allocator */ + + return 1; +} + +/* + * Remove huge page from pool from next node to free. Attempt to keep + * persistent huge pages more or less balanced over allowed nodes. + * This routine only 'removes' the hugetlb page. The caller must make + * an additional call to free the page to low level allocators. + * Called with hugetlb_lock locked. + */ +static struct page *remove_pool_huge_page(struct hstate *h, + nodemask_t *nodes_allowed, + bool acct_surplus) +{ + int nr_nodes, node; + struct page *page = NULL; + + lockdep_assert_held(&hugetlb_lock); + for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { + /* + * If we're returning unused surplus pages, only examine + * nodes with surplus pages. + */ + if ((!acct_surplus || h->surplus_huge_pages_node[node]) && + !list_empty(&h->hugepage_freelists[node])) { + page = list_entry(h->hugepage_freelists[node].next, + struct page, lru); + remove_hugetlb_page(h, page, acct_surplus); + break; + } + } + + return page; +} + +/* + * Dissolve a given free hugepage into free buddy pages. This function does + * nothing for in-use hugepages and non-hugepages. + * This function returns values like below: + * + * -ENOMEM: failed to allocate vmemmap pages to free the freed hugepages + * when the system is under memory pressure and the feature of + * freeing unused vmemmap pages associated with each hugetlb page + * is enabled. + * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use + * (allocated or reserved.) + * 0: successfully dissolved free hugepages or the page is not a + * hugepage (considered as already dissolved) + */ +int dissolve_free_huge_page(struct page *page) +{ + int rc = -EBUSY; + +retry: + /* Not to disrupt normal path by vainly holding hugetlb_lock */ + if (!PageHuge(page)) + return 0; + + spin_lock_irq(&hugetlb_lock); + if (!PageHuge(page)) { + rc = 0; + goto out; + } + + if (!page_count(page)) { + struct page *head = compound_head(page); + struct hstate *h = page_hstate(head); + if (!available_huge_pages(h)) + goto out; + + /* + * We should make sure that the page is already on the free list + * when it is dissolved. + */ + if (unlikely(!HPageFreed(head))) { + spin_unlock_irq(&hugetlb_lock); + cond_resched(); + + /* + * Theoretically, we should return -EBUSY when we + * encounter this race. In fact, we have a chance + * to successfully dissolve the page if we do a + * retry. Because the race window is quite small. + * If we seize this opportunity, it is an optimization + * for increasing the success rate of dissolving page. + */ + goto retry; + } + + remove_hugetlb_page(h, head, false); + h->max_huge_pages--; + spin_unlock_irq(&hugetlb_lock); + + /* + * Normally update_and_free_page will allocate required vmemmmap + * before freeing the page. update_and_free_page will fail to + * free the page if it can not allocate required vmemmap. We + * need to adjust max_huge_pages if the page is not freed. + * Attempt to allocate vmemmmap here so that we can take + * appropriate action on failure. + */ + rc = hugetlb_vmemmap_restore(h, head); + if (!rc) { + update_and_free_page(h, head, false); + } else { + spin_lock_irq(&hugetlb_lock); + add_hugetlb_page(h, head, false); + h->max_huge_pages++; + spin_unlock_irq(&hugetlb_lock); + } + + return rc; + } +out: + spin_unlock_irq(&hugetlb_lock); + return rc; +} + +/* + * Dissolve free hugepages in a given pfn range. Used by memory hotplug to + * make specified memory blocks removable from the system. + * Note that this will dissolve a free gigantic hugepage completely, if any + * part of it lies within the given range. + * Also note that if dissolve_free_huge_page() returns with an error, all + * free hugepages that were dissolved before that error are lost. + */ +int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pfn; + struct page *page; + int rc = 0; + unsigned int order; + struct hstate *h; + + if (!hugepages_supported()) + return rc; + + order = huge_page_order(&default_hstate); + for_each_hstate(h) + order = min(order, huge_page_order(h)); + + for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) { + page = pfn_to_page(pfn); + rc = dissolve_free_huge_page(page); + if (rc) + break; + } + + return rc; +} + +/* + * Allocates a fresh surplus page from the page allocator. + */ +static struct page *alloc_surplus_huge_page(struct hstate *h, gfp_t gfp_mask, + int nid, nodemask_t *nmask) +{ + struct page *page = NULL; + + if (hstate_is_gigantic(h)) + return NULL; + + spin_lock_irq(&hugetlb_lock); + if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) + goto out_unlock; + spin_unlock_irq(&hugetlb_lock); + + page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL); + if (!page) + return NULL; + + spin_lock_irq(&hugetlb_lock); + /* + * We could have raced with the pool size change. + * Double check that and simply deallocate the new page + * if we would end up overcommiting the surpluses. Abuse + * temporary page to workaround the nasty free_huge_page + * codeflow + */ + if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { + SetHPageTemporary(page); + spin_unlock_irq(&hugetlb_lock); + free_huge_page(page); + return NULL; + } + + h->surplus_huge_pages++; + h->surplus_huge_pages_node[page_to_nid(page)]++; + +out_unlock: + spin_unlock_irq(&hugetlb_lock); + + return page; +} + +static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask, + int nid, nodemask_t *nmask) +{ + struct page *page; + + if (hstate_is_gigantic(h)) + return NULL; + + page = alloc_fresh_huge_page(h, gfp_mask, nid, nmask, NULL); + if (!page) + return NULL; + + /* fresh huge pages are frozen */ + set_page_refcounted(page); + + /* + * We do not account these pages as surplus because they are only + * temporary and will be released properly on the last reference + */ + SetHPageTemporary(page); + + return page; +} + +/* + * Use the VMA's mpolicy to allocate a huge page from the buddy. + */ +static +struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + struct page *page = NULL; + struct mempolicy *mpol; + gfp_t gfp_mask = htlb_alloc_mask(h); + int nid; + nodemask_t *nodemask; + + nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask); + if (mpol_is_preferred_many(mpol)) { + gfp_t gfp = gfp_mask | __GFP_NOWARN; + + gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL); + page = alloc_surplus_huge_page(h, gfp, nid, nodemask); + + /* Fallback to all nodes if page==NULL */ + nodemask = NULL; + } + + if (!page) + page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask); + mpol_cond_put(mpol); + return page; +} + +/* page migration callback function */ +struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid, + nodemask_t *nmask, gfp_t gfp_mask) +{ + spin_lock_irq(&hugetlb_lock); + if (available_huge_pages(h)) { + struct page *page; + + page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask); + if (page) { + spin_unlock_irq(&hugetlb_lock); + return page; + } + } + spin_unlock_irq(&hugetlb_lock); + + return alloc_migrate_huge_page(h, gfp_mask, preferred_nid, nmask); +} + +/* mempolicy aware migration callback */ +struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma, + unsigned long address) +{ + struct mempolicy *mpol; + nodemask_t *nodemask; + struct page *page; + gfp_t gfp_mask; + int node; + + gfp_mask = htlb_alloc_mask(h); + node = huge_node(vma, address, gfp_mask, &mpol, &nodemask); + page = alloc_huge_page_nodemask(h, node, nodemask, gfp_mask); + mpol_cond_put(mpol); + + return page; +} + +/* + * Increase the hugetlb pool such that it can accommodate a reservation + * of size 'delta'. + */ +static int gather_surplus_pages(struct hstate *h, long delta) + __must_hold(&hugetlb_lock) +{ + LIST_HEAD(surplus_list); + struct page *page, *tmp; + int ret; + long i; + long needed, allocated; + bool alloc_ok = true; + + lockdep_assert_held(&hugetlb_lock); + needed = (h->resv_huge_pages + delta) - h->free_huge_pages; + if (needed <= 0) { + h->resv_huge_pages += delta; + return 0; + } + + allocated = 0; + + ret = -ENOMEM; +retry: + spin_unlock_irq(&hugetlb_lock); + for (i = 0; i < needed; i++) { + page = alloc_surplus_huge_page(h, htlb_alloc_mask(h), + NUMA_NO_NODE, NULL); + if (!page) { + alloc_ok = false; + break; + } + list_add(&page->lru, &surplus_list); + cond_resched(); + } + allocated += i; + + /* + * After retaking hugetlb_lock, we need to recalculate 'needed' + * because either resv_huge_pages or free_huge_pages may have changed. + */ + spin_lock_irq(&hugetlb_lock); + needed = (h->resv_huge_pages + delta) - + (h->free_huge_pages + allocated); + if (needed > 0) { + if (alloc_ok) + goto retry; + /* + * We were not able to allocate enough pages to + * satisfy the entire reservation so we free what + * we've allocated so far. + */ + goto free; + } + /* + * The surplus_list now contains _at_least_ the number of extra pages + * needed to accommodate the reservation. Add the appropriate number + * of pages to the hugetlb pool and free the extras back to the buddy + * allocator. Commit the entire reservation here to prevent another + * process from stealing the pages as they are added to the pool but + * before they are reserved. + */ + needed += allocated; + h->resv_huge_pages += delta; + ret = 0; + + /* Free the needed pages to the hugetlb pool */ + list_for_each_entry_safe(page, tmp, &surplus_list, lru) { + if ((--needed) < 0) + break; + /* Add the page to the hugetlb allocator */ + enqueue_huge_page(h, page); + } +free: + spin_unlock_irq(&hugetlb_lock); + + /* + * Free unnecessary surplus pages to the buddy allocator. + * Pages have no ref count, call free_huge_page directly. + */ + list_for_each_entry_safe(page, tmp, &surplus_list, lru) + free_huge_page(page); + spin_lock_irq(&hugetlb_lock); + + return ret; +} + +/* + * This routine has two main purposes: + * 1) Decrement the reservation count (resv_huge_pages) by the value passed + * in unused_resv_pages. This corresponds to the prior adjustments made + * to the associated reservation map. + * 2) Free any unused surplus pages that may have been allocated to satisfy + * the reservation. As many as unused_resv_pages may be freed. + */ +static void return_unused_surplus_pages(struct hstate *h, + unsigned long unused_resv_pages) +{ + unsigned long nr_pages; + struct page *page; + LIST_HEAD(page_list); + + lockdep_assert_held(&hugetlb_lock); + /* Uncommit the reservation */ + h->resv_huge_pages -= unused_resv_pages; + + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) + goto out; + + /* + * Part (or even all) of the reservation could have been backed + * by pre-allocated pages. Only free surplus pages. + */ + nr_pages = min(unused_resv_pages, h->surplus_huge_pages); + + /* + * We want to release as many surplus pages as possible, spread + * evenly across all nodes with memory. Iterate across these nodes + * until we can no longer free unreserved surplus pages. This occurs + * when the nodes with surplus pages have no free pages. + * remove_pool_huge_page() will balance the freed pages across the + * on-line nodes with memory and will handle the hstate accounting. + */ + while (nr_pages--) { + page = remove_pool_huge_page(h, &node_states[N_MEMORY], 1); + if (!page) + goto out; + + list_add(&page->lru, &page_list); + } + +out: + spin_unlock_irq(&hugetlb_lock); + update_and_free_pages_bulk(h, &page_list); + spin_lock_irq(&hugetlb_lock); +} + + +/* + * vma_needs_reservation, vma_commit_reservation and vma_end_reservation + * are used by the huge page allocation routines to manage reservations. + * + * vma_needs_reservation is called to determine if the huge page at addr + * within the vma has an associated reservation. If a reservation is + * needed, the value 1 is returned. The caller is then responsible for + * managing the global reservation and subpool usage counts. After + * the huge page has been allocated, vma_commit_reservation is called + * to add the page to the reservation map. If the page allocation fails, + * the reservation must be ended instead of committed. vma_end_reservation + * is called in such cases. + * + * In the normal case, vma_commit_reservation returns the same value + * as the preceding vma_needs_reservation call. The only time this + * is not the case is if a reserve map was changed between calls. It + * is the responsibility of the caller to notice the difference and + * take appropriate action. + * + * vma_add_reservation is used in error paths where a reservation must + * be restored when a newly allocated huge page must be freed. It is + * to be called after calling vma_needs_reservation to determine if a + * reservation exists. + * + * vma_del_reservation is used in error paths where an entry in the reserve + * map was created during huge page allocation and must be removed. It is to + * be called after calling vma_needs_reservation to determine if a reservation + * exists. + */ +enum vma_resv_mode { + VMA_NEEDS_RESV, + VMA_COMMIT_RESV, + VMA_END_RESV, + VMA_ADD_RESV, + VMA_DEL_RESV, +}; +static long __vma_reservation_common(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr, + enum vma_resv_mode mode) +{ + struct resv_map *resv; + pgoff_t idx; + long ret; + long dummy_out_regions_needed; + + resv = vma_resv_map(vma); + if (!resv) + return 1; + + idx = vma_hugecache_offset(h, vma, addr); + switch (mode) { + case VMA_NEEDS_RESV: + ret = region_chg(resv, idx, idx + 1, &dummy_out_regions_needed); + /* We assume that vma_reservation_* routines always operate on + * 1 page, and that adding to resv map a 1 page entry can only + * ever require 1 region. + */ + VM_BUG_ON(dummy_out_regions_needed != 1); + break; + case VMA_COMMIT_RESV: + ret = region_add(resv, idx, idx + 1, 1, NULL, NULL); + /* region_add calls of range 1 should never fail. */ + VM_BUG_ON(ret < 0); + break; + case VMA_END_RESV: + region_abort(resv, idx, idx + 1, 1); + ret = 0; + break; + case VMA_ADD_RESV: + if (vma->vm_flags & VM_MAYSHARE) { + ret = region_add(resv, idx, idx + 1, 1, NULL, NULL); + /* region_add calls of range 1 should never fail. */ + VM_BUG_ON(ret < 0); + } else { + region_abort(resv, idx, idx + 1, 1); + ret = region_del(resv, idx, idx + 1); + } + break; + case VMA_DEL_RESV: + if (vma->vm_flags & VM_MAYSHARE) { + region_abort(resv, idx, idx + 1, 1); + ret = region_del(resv, idx, idx + 1); + } else { + ret = region_add(resv, idx, idx + 1, 1, NULL, NULL); + /* region_add calls of range 1 should never fail. */ + VM_BUG_ON(ret < 0); + } + break; + default: + BUG(); + } + + if (vma->vm_flags & VM_MAYSHARE || mode == VMA_DEL_RESV) + return ret; + /* + * We know private mapping must have HPAGE_RESV_OWNER set. + * + * In most cases, reserves always exist for private mappings. + * However, a file associated with mapping could have been + * hole punched or truncated after reserves were consumed. + * As subsequent fault on such a range will not use reserves. + * Subtle - The reserve map for private mappings has the + * opposite meaning than that of shared mappings. If NO + * entry is in the reserve map, it means a reservation exists. + * If an entry exists in the reserve map, it means the + * reservation has already been consumed. As a result, the + * return value of this routine is the opposite of the + * value returned from reserve map manipulation routines above. + */ + if (ret > 0) + return 0; + if (ret == 0) + return 1; + return ret; +} + +static long vma_needs_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + return __vma_reservation_common(h, vma, addr, VMA_NEEDS_RESV); +} + +static long vma_commit_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + return __vma_reservation_common(h, vma, addr, VMA_COMMIT_RESV); +} + +static void vma_end_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + (void)__vma_reservation_common(h, vma, addr, VMA_END_RESV); +} + +static long vma_add_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + return __vma_reservation_common(h, vma, addr, VMA_ADD_RESV); +} + +static long vma_del_reservation(struct hstate *h, + struct vm_area_struct *vma, unsigned long addr) +{ + return __vma_reservation_common(h, vma, addr, VMA_DEL_RESV); +} + +/* + * This routine is called to restore reservation information on error paths. + * It should ONLY be called for pages allocated via alloc_huge_page(), and + * the hugetlb mutex should remain held when calling this routine. + * + * It handles two specific cases: + * 1) A reservation was in place and the page consumed the reservation. + * HPageRestoreReserve is set in the page. + * 2) No reservation was in place for the page, so HPageRestoreReserve is + * not set. However, alloc_huge_page always updates the reserve map. + * + * In case 1, free_huge_page later in the error path will increment the + * global reserve count. But, free_huge_page does not have enough context + * to adjust the reservation map. This case deals primarily with private + * mappings. Adjust the reserve map here to be consistent with global + * reserve count adjustments to be made by free_huge_page. Make sure the + * reserve map indicates there is a reservation present. + * + * In case 2, simply undo reserve map modifications done by alloc_huge_page. + */ +void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma, + unsigned long address, struct page *page) +{ + long rc = vma_needs_reservation(h, vma, address); + + if (HPageRestoreReserve(page)) { + if (unlikely(rc < 0)) + /* + * Rare out of memory condition in reserve map + * manipulation. Clear HPageRestoreReserve so that + * global reserve count will not be incremented + * by free_huge_page. This will make it appear + * as though the reservation for this page was + * consumed. This may prevent the task from + * faulting in the page at a later time. This + * is better than inconsistent global huge page + * accounting of reserve counts. + */ + ClearHPageRestoreReserve(page); + else if (rc) + (void)vma_add_reservation(h, vma, address); + else + vma_end_reservation(h, vma, address); + } else { + if (!rc) { + /* + * This indicates there is an entry in the reserve map + * not added by alloc_huge_page. We know it was added + * before the alloc_huge_page call, otherwise + * HPageRestoreReserve would be set on the page. + * Remove the entry so that a subsequent allocation + * does not consume a reservation. + */ + rc = vma_del_reservation(h, vma, address); + if (rc < 0) + /* + * VERY rare out of memory condition. Since + * we can not delete the entry, set + * HPageRestoreReserve so that the reserve + * count will be incremented when the page + * is freed. This reserve will be consumed + * on a subsequent allocation. + */ + SetHPageRestoreReserve(page); + } else if (rc < 0) { + /* + * Rare out of memory condition from + * vma_needs_reservation call. Memory allocation is + * only attempted if a new entry is needed. Therefore, + * this implies there is not an entry in the + * reserve map. + * + * For shared mappings, no entry in the map indicates + * no reservation. We are done. + */ + if (!(vma->vm_flags & VM_MAYSHARE)) + /* + * For private mappings, no entry indicates + * a reservation is present. Since we can + * not add an entry, set SetHPageRestoreReserve + * on the page so reserve count will be + * incremented when freed. This reserve will + * be consumed on a subsequent allocation. + */ + SetHPageRestoreReserve(page); + } else + /* + * No reservation present, do nothing + */ + vma_end_reservation(h, vma, address); + } +} + +/* + * alloc_and_dissolve_huge_page - Allocate a new page and dissolve the old one + * @h: struct hstate old page belongs to + * @old_page: Old page to dissolve + * @list: List to isolate the page in case we need to + * Returns 0 on success, otherwise negated error. + */ +static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page, + struct list_head *list) +{ + gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; + int nid = page_to_nid(old_page); + struct page *new_page; + int ret = 0; + + /* + * Before dissolving the page, we need to allocate a new one for the + * pool to remain stable. Here, we allocate the page and 'prep' it + * by doing everything but actually updating counters and adding to + * the pool. This simplifies and let us do most of the processing + * under the lock. + */ + new_page = alloc_buddy_huge_page(h, gfp_mask, nid, NULL, NULL); + if (!new_page) + return -ENOMEM; + __prep_new_huge_page(h, new_page); + +retry: + spin_lock_irq(&hugetlb_lock); + if (!PageHuge(old_page)) { + /* + * Freed from under us. Drop new_page too. + */ + goto free_new; + } else if (page_count(old_page)) { + /* + * Someone has grabbed the page, try to isolate it here. + * Fail with -EBUSY if not possible. + */ + spin_unlock_irq(&hugetlb_lock); + ret = isolate_hugetlb(old_page, list); + spin_lock_irq(&hugetlb_lock); + goto free_new; + } else if (!HPageFreed(old_page)) { + /* + * Page's refcount is 0 but it has not been enqueued in the + * freelist yet. Race window is small, so we can succeed here if + * we retry. + */ + spin_unlock_irq(&hugetlb_lock); + cond_resched(); + goto retry; + } else { + /* + * Ok, old_page is still a genuine free hugepage. Remove it from + * the freelist and decrease the counters. These will be + * incremented again when calling __prep_account_new_huge_page() + * and enqueue_huge_page() for new_page. The counters will remain + * stable since this happens under the lock. + */ + remove_hugetlb_page(h, old_page, false); + + /* + * Ref count on new page is already zero as it was dropped + * earlier. It can be directly added to the pool free list. + */ + __prep_account_new_huge_page(h, nid); + enqueue_huge_page(h, new_page); + + /* + * Pages have been replaced, we can safely free the old one. + */ + spin_unlock_irq(&hugetlb_lock); + update_and_free_page(h, old_page, false); + } + + return ret; + +free_new: + spin_unlock_irq(&hugetlb_lock); + /* Page has a zero ref count, but needs a ref to be freed */ + set_page_refcounted(new_page); + update_and_free_page(h, new_page, false); + + return ret; +} + +int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list) +{ + struct hstate *h; + struct page *head; + int ret = -EBUSY; + + /* + * The page might have been dissolved from under our feet, so make sure + * to carefully check the state under the lock. + * Return success when racing as if we dissolved the page ourselves. + */ + spin_lock_irq(&hugetlb_lock); + if (PageHuge(page)) { + head = compound_head(page); + h = page_hstate(head); + } else { + spin_unlock_irq(&hugetlb_lock); + return 0; + } + spin_unlock_irq(&hugetlb_lock); + + /* + * Fence off gigantic pages as there is a cyclic dependency between + * alloc_contig_range and them. Return -ENOMEM as this has the effect + * of bailing out right away without further retrying. + */ + if (hstate_is_gigantic(h)) + return -ENOMEM; + + if (page_count(head) && !isolate_hugetlb(head, list)) + ret = 0; + else if (!page_count(head)) + ret = alloc_and_dissolve_huge_page(h, head, list); + + return ret; +} + +struct page *alloc_huge_page(struct vm_area_struct *vma, + unsigned long addr, int avoid_reserve) +{ + struct hugepage_subpool *spool = subpool_vma(vma); + struct hstate *h = hstate_vma(vma); + struct page *page; + long map_chg, map_commit; + long gbl_chg; + int ret, idx; + struct hugetlb_cgroup *h_cg; + bool deferred_reserve; + + idx = hstate_index(h); + /* + * Examine the region/reserve map to determine if the process + * has a reservation for the page to be allocated. A return + * code of zero indicates a reservation exists (no change). + */ + map_chg = gbl_chg = vma_needs_reservation(h, vma, addr); + if (map_chg < 0) + return ERR_PTR(-ENOMEM); + + /* + * Processes that did not create the mapping will have no + * reserves as indicated by the region/reserve map. Check + * that the allocation will not exceed the subpool limit. + * Allocations for MAP_NORESERVE mappings also need to be + * checked against any subpool limit. + */ + if (map_chg || avoid_reserve) { + gbl_chg = hugepage_subpool_get_pages(spool, 1); + if (gbl_chg < 0) { + vma_end_reservation(h, vma, addr); + return ERR_PTR(-ENOSPC); + } + + /* + * Even though there was no reservation in the region/reserve + * map, there could be reservations associated with the + * subpool that can be used. This would be indicated if the + * return value of hugepage_subpool_get_pages() is zero. + * However, if avoid_reserve is specified we still avoid even + * the subpool reservations. + */ + if (avoid_reserve) + gbl_chg = 1; + } + + /* If this allocation is not consuming a reservation, charge it now. + */ + deferred_reserve = map_chg || avoid_reserve; + if (deferred_reserve) { + ret = hugetlb_cgroup_charge_cgroup_rsvd( + idx, pages_per_huge_page(h), &h_cg); + if (ret) + goto out_subpool_put; + } + + ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); + if (ret) + goto out_uncharge_cgroup_reservation; + + spin_lock_irq(&hugetlb_lock); + /* + * glb_chg is passed to indicate whether or not a page must be taken + * from the global free pool (global change). gbl_chg == 0 indicates + * a reservation exists for the allocation. + */ + page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg); + if (!page) { + spin_unlock_irq(&hugetlb_lock); + page = alloc_buddy_huge_page_with_mpol(h, vma, addr); + if (!page) + goto out_uncharge_cgroup; + spin_lock_irq(&hugetlb_lock); + if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) { + SetHPageRestoreReserve(page); + h->resv_huge_pages--; + } + list_add(&page->lru, &h->hugepage_activelist); + set_page_refcounted(page); + /* Fall through */ + } + hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page); + /* If allocation is not consuming a reservation, also store the + * hugetlb_cgroup pointer on the page. + */ + if (deferred_reserve) { + hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h), + h_cg, page); + } + + spin_unlock_irq(&hugetlb_lock); + + hugetlb_set_page_subpool(page, spool); + + map_commit = vma_commit_reservation(h, vma, addr); + if (unlikely(map_chg > map_commit)) { + /* + * The page was added to the reservation map between + * vma_needs_reservation and vma_commit_reservation. + * This indicates a race with hugetlb_reserve_pages. + * Adjust for the subpool count incremented above AND + * in hugetlb_reserve_pages for the same page. Also, + * the reservation count added in hugetlb_reserve_pages + * no longer applies. + */ + long rsv_adjust; + + rsv_adjust = hugepage_subpool_put_pages(spool, 1); + hugetlb_acct_memory(h, -rsv_adjust); + if (deferred_reserve) + hugetlb_cgroup_uncharge_page_rsvd(hstate_index(h), + pages_per_huge_page(h), page); + } + return page; + +out_uncharge_cgroup: + hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg); +out_uncharge_cgroup_reservation: + if (deferred_reserve) + hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h), + h_cg); +out_subpool_put: + if (map_chg || avoid_reserve) + hugepage_subpool_put_pages(spool, 1); + vma_end_reservation(h, vma, addr); + return ERR_PTR(-ENOSPC); +} + +int alloc_bootmem_huge_page(struct hstate *h, int nid) + __attribute__ ((weak, alias("__alloc_bootmem_huge_page"))); +int __alloc_bootmem_huge_page(struct hstate *h, int nid) +{ + struct huge_bootmem_page *m = NULL; /* initialize for clang */ + int nr_nodes, node; + + /* do node specific alloc */ + if (nid != NUMA_NO_NODE) { + m = memblock_alloc_try_nid_raw(huge_page_size(h), huge_page_size(h), + 0, MEMBLOCK_ALLOC_ACCESSIBLE, nid); + if (!m) + return 0; + goto found; + } + /* allocate from next node when distributing huge pages */ + for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) { + m = memblock_alloc_try_nid_raw( + huge_page_size(h), huge_page_size(h), + 0, MEMBLOCK_ALLOC_ACCESSIBLE, node); + /* + * Use the beginning of the huge page to store the + * huge_bootmem_page struct (until gather_bootmem + * puts them into the mem_map). + */ + if (!m) + return 0; + goto found; + } + +found: + /* Put them into a private list first because mem_map is not up yet */ + INIT_LIST_HEAD(&m->list); + list_add(&m->list, &huge_boot_pages); + m->hstate = h; + return 1; +} + +/* + * Put bootmem huge pages into the standard lists after mem_map is up. + * Note: This only applies to gigantic (order > MAX_ORDER) pages. + */ +static void __init gather_bootmem_prealloc(void) +{ + struct huge_bootmem_page *m; + + list_for_each_entry(m, &huge_boot_pages, list) { + struct page *page = virt_to_page(m); + struct hstate *h = m->hstate; + + VM_BUG_ON(!hstate_is_gigantic(h)); + WARN_ON(page_count(page) != 1); + if (prep_compound_gigantic_page(page, huge_page_order(h))) { + WARN_ON(PageReserved(page)); + prep_new_huge_page(h, page, page_to_nid(page)); + free_huge_page(page); /* add to the hugepage allocator */ + } else { + /* VERY unlikely inflated ref count on a tail page */ + free_gigantic_page(page, huge_page_order(h)); + } + + /* + * We need to restore the 'stolen' pages to totalram_pages + * in order to fix confusing memory reports from free(1) and + * other side-effects, like CommitLimit going negative. + */ + adjust_managed_page_count(page, pages_per_huge_page(h)); + cond_resched(); + } +} +static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid) +{ + unsigned long i; + char buf[32]; + + for (i = 0; i < h->max_huge_pages_node[nid]; ++i) { + if (hstate_is_gigantic(h)) { + if (!alloc_bootmem_huge_page(h, nid)) + break; + } else { + struct page *page; + gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; + + page = alloc_fresh_huge_page(h, gfp_mask, nid, + &node_states[N_MEMORY], NULL); + if (!page) + break; + free_huge_page(page); /* free it into the hugepage allocator */ + } + cond_resched(); + } + if (i == h->max_huge_pages_node[nid]) + return; + + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32); + pr_warn("HugeTLB: allocating %u of page size %s failed node%d. Only allocated %lu hugepages.\n", + h->max_huge_pages_node[nid], buf, nid, i); + h->max_huge_pages -= (h->max_huge_pages_node[nid] - i); + h->max_huge_pages_node[nid] = i; +} + +static void __init hugetlb_hstate_alloc_pages(struct hstate *h) +{ + unsigned long i; + nodemask_t *node_alloc_noretry; + bool node_specific_alloc = false; + + /* skip gigantic hugepages allocation if hugetlb_cma enabled */ + if (hstate_is_gigantic(h) && hugetlb_cma_size) { + pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip boot time allocation\n"); + return; + } + + /* do node specific alloc */ + for_each_online_node(i) { + if (h->max_huge_pages_node[i] > 0) { + hugetlb_hstate_alloc_pages_onenode(h, i); + node_specific_alloc = true; + } + } + + if (node_specific_alloc) + return; + + /* below will do all node balanced alloc */ + if (!hstate_is_gigantic(h)) { + /* + * Bit mask controlling how hard we retry per-node allocations. + * Ignore errors as lower level routines can deal with + * node_alloc_noretry == NULL. If this kmalloc fails at boot + * time, we are likely in bigger trouble. + */ + node_alloc_noretry = kmalloc(sizeof(*node_alloc_noretry), + GFP_KERNEL); + } else { + /* allocations done at boot time */ + node_alloc_noretry = NULL; + } + + /* bit mask controlling how hard we retry per-node allocations */ + if (node_alloc_noretry) + nodes_clear(*node_alloc_noretry); + + for (i = 0; i < h->max_huge_pages; ++i) { + if (hstate_is_gigantic(h)) { + if (!alloc_bootmem_huge_page(h, NUMA_NO_NODE)) + break; + } else if (!alloc_pool_huge_page(h, + &node_states[N_MEMORY], + node_alloc_noretry)) + break; + cond_resched(); + } + if (i < h->max_huge_pages) { + char buf[32]; + + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32); + pr_warn("HugeTLB: allocating %lu of page size %s failed. Only allocated %lu hugepages.\n", + h->max_huge_pages, buf, i); + h->max_huge_pages = i; + } + kfree(node_alloc_noretry); +} + +static void __init hugetlb_init_hstates(void) +{ + struct hstate *h, *h2; + + for_each_hstate(h) { + /* oversize hugepages were init'ed in early boot */ + if (!hstate_is_gigantic(h)) + hugetlb_hstate_alloc_pages(h); + + /* + * Set demote order for each hstate. Note that + * h->demote_order is initially 0. + * - We can not demote gigantic pages if runtime freeing + * is not supported, so skip this. + * - If CMA allocation is possible, we can not demote + * HUGETLB_PAGE_ORDER or smaller size pages. + */ + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) + continue; + if (hugetlb_cma_size && h->order <= HUGETLB_PAGE_ORDER) + continue; + for_each_hstate(h2) { + if (h2 == h) + continue; + if (h2->order < h->order && + h2->order > h->demote_order) + h->demote_order = h2->order; + } + } +} + +static void __init report_hugepages(void) +{ + struct hstate *h; + + for_each_hstate(h) { + char buf[32]; + + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32); + pr_info("HugeTLB: registered %s page size, pre-allocated %ld pages\n", + buf, h->free_huge_pages); + pr_info("HugeTLB: %d KiB vmemmap can be freed for a %s page\n", + hugetlb_vmemmap_optimizable_size(h) / SZ_1K, buf); + } +} + +#ifdef CONFIG_HIGHMEM +static void try_to_free_low(struct hstate *h, unsigned long count, + nodemask_t *nodes_allowed) +{ + int i; + LIST_HEAD(page_list); + + lockdep_assert_held(&hugetlb_lock); + if (hstate_is_gigantic(h)) + return; + + /* + * Collect pages to be freed on a list, and free after dropping lock + */ + for_each_node_mask(i, *nodes_allowed) { + struct page *page, *next; + struct list_head *freel = &h->hugepage_freelists[i]; + list_for_each_entry_safe(page, next, freel, lru) { + if (count >= h->nr_huge_pages) + goto out; + if (PageHighMem(page)) + continue; + remove_hugetlb_page(h, page, false); + list_add(&page->lru, &page_list); + } + } + +out: + spin_unlock_irq(&hugetlb_lock); + update_and_free_pages_bulk(h, &page_list); + spin_lock_irq(&hugetlb_lock); +} +#else +static inline void try_to_free_low(struct hstate *h, unsigned long count, + nodemask_t *nodes_allowed) +{ +} +#endif + +/* + * Increment or decrement surplus_huge_pages. Keep node-specific counters + * balanced by operating on them in a round-robin fashion. + * Returns 1 if an adjustment was made. + */ +static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, + int delta) +{ + int nr_nodes, node; + + lockdep_assert_held(&hugetlb_lock); + VM_BUG_ON(delta != -1 && delta != 1); + + if (delta < 0) { + for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { + if (h->surplus_huge_pages_node[node]) + goto found; + } + } else { + for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { + if (h->surplus_huge_pages_node[node] < + h->nr_huge_pages_node[node]) + goto found; + } + } + return 0; + +found: + h->surplus_huge_pages += delta; + h->surplus_huge_pages_node[node] += delta; + return 1; +} + +#define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) +static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid, + nodemask_t *nodes_allowed) +{ + unsigned long min_count, ret; + struct page *page; + LIST_HEAD(page_list); + NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL); + + /* + * Bit mask controlling how hard we retry per-node allocations. + * If we can not allocate the bit mask, do not attempt to allocate + * the requested huge pages. + */ + if (node_alloc_noretry) + nodes_clear(*node_alloc_noretry); + else + return -ENOMEM; + + /* + * resize_lock mutex prevents concurrent adjustments to number of + * pages in hstate via the proc/sysfs interfaces. + */ + mutex_lock(&h->resize_lock); + flush_free_hpage_work(h); + spin_lock_irq(&hugetlb_lock); + + /* + * Check for a node specific request. + * Changing node specific huge page count may require a corresponding + * change to the global count. In any case, the passed node mask + * (nodes_allowed) will restrict alloc/free to the specified node. + */ + if (nid != NUMA_NO_NODE) { + unsigned long old_count = count; + + count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; + /* + * User may have specified a large count value which caused the + * above calculation to overflow. In this case, they wanted + * to allocate as many huge pages as possible. Set count to + * largest possible value to align with their intention. + */ + if (count < old_count) + count = ULONG_MAX; + } + + /* + * Gigantic pages runtime allocation depend on the capability for large + * page range allocation. + * If the system does not provide this feature, return an error when + * the user tries to allocate gigantic pages but let the user free the + * boottime allocated gigantic pages. + */ + if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) { + if (count > persistent_huge_pages(h)) { + spin_unlock_irq(&hugetlb_lock); + mutex_unlock(&h->resize_lock); + NODEMASK_FREE(node_alloc_noretry); + return -EINVAL; + } + /* Fall through to decrease pool */ + } + + /* + * Increase the pool size + * First take pages out of surplus state. Then make up the + * remaining difference by allocating fresh huge pages. + * + * We might race with alloc_surplus_huge_page() here and be unable + * to convert a surplus huge page to a normal huge page. That is + * not critical, though, it just means the overall size of the + * pool might be one hugepage larger than it needs to be, but + * within all the constraints specified by the sysctls. + */ + while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { + if (!adjust_pool_surplus(h, nodes_allowed, -1)) + break; + } + + while (count > persistent_huge_pages(h)) { + /* + * If this allocation races such that we no longer need the + * page, free_huge_page will handle it by freeing the page + * and reducing the surplus. + */ + spin_unlock_irq(&hugetlb_lock); + + /* yield cpu to avoid soft lockup */ + cond_resched(); + + ret = alloc_pool_huge_page(h, nodes_allowed, + node_alloc_noretry); + spin_lock_irq(&hugetlb_lock); + if (!ret) + goto out; + + /* Bail for signals. Probably ctrl-c from user */ + if (signal_pending(current)) + goto out; + } + + /* + * Decrease the pool size + * First return free pages to the buddy allocator (being careful + * to keep enough around to satisfy reservations). Then place + * pages into surplus state as needed so the pool will shrink + * to the desired size as pages become free. + * + * By placing pages into the surplus state independent of the + * overcommit value, we are allowing the surplus pool size to + * exceed overcommit. There are few sane options here. Since + * alloc_surplus_huge_page() is checking the global counter, + * though, we'll note that we're not allowed to exceed surplus + * and won't grow the pool anywhere else. Not until one of the + * sysctls are changed, or the surplus pages go out of use. + */ + min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; + min_count = max(count, min_count); + try_to_free_low(h, min_count, nodes_allowed); + + /* + * Collect pages to be removed on list without dropping lock + */ + while (min_count < persistent_huge_pages(h)) { + page = remove_pool_huge_page(h, nodes_allowed, 0); + if (!page) + break; + + list_add(&page->lru, &page_list); + } + /* free the pages after dropping lock */ + spin_unlock_irq(&hugetlb_lock); + update_and_free_pages_bulk(h, &page_list); + flush_free_hpage_work(h); + spin_lock_irq(&hugetlb_lock); + + while (count < persistent_huge_pages(h)) { + if (!adjust_pool_surplus(h, nodes_allowed, 1)) + break; + } +out: + h->max_huge_pages = persistent_huge_pages(h); + spin_unlock_irq(&hugetlb_lock); + mutex_unlock(&h->resize_lock); + + NODEMASK_FREE(node_alloc_noretry); + + return 0; +} + +static int demote_free_huge_page(struct hstate *h, struct page *page) +{ + int i, nid = page_to_nid(page); + struct hstate *target_hstate; + struct page *subpage; + int rc = 0; + + target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order); + + remove_hugetlb_page_for_demote(h, page, false); + spin_unlock_irq(&hugetlb_lock); + + rc = hugetlb_vmemmap_restore(h, page); + if (rc) { + /* Allocation of vmemmmap failed, we can not demote page */ + spin_lock_irq(&hugetlb_lock); + set_page_refcounted(page); + add_hugetlb_page(h, page, false); + return rc; + } + + /* + * Use destroy_compound_hugetlb_page_for_demote for all huge page + * sizes as it will not ref count pages. + */ + destroy_compound_hugetlb_page_for_demote(page, huge_page_order(h)); + + /* + * Taking target hstate mutex synchronizes with set_max_huge_pages. + * Without the mutex, pages added to target hstate could be marked + * as surplus. + * + * Note that we already hold h->resize_lock. To prevent deadlock, + * use the convention of always taking larger size hstate mutex first. + */ + mutex_lock(&target_hstate->resize_lock); + for (i = 0; i < pages_per_huge_page(h); + i += pages_per_huge_page(target_hstate)) { + subpage = nth_page(page, i); + if (hstate_is_gigantic(target_hstate)) + prep_compound_gigantic_page_for_demote(subpage, + target_hstate->order); + else + prep_compound_page(subpage, target_hstate->order); + set_page_private(subpage, 0); + prep_new_huge_page(target_hstate, subpage, nid); + free_huge_page(subpage); + } + mutex_unlock(&target_hstate->resize_lock); + + spin_lock_irq(&hugetlb_lock); + + /* + * Not absolutely necessary, but for consistency update max_huge_pages + * based on pool changes for the demoted page. + */ + h->max_huge_pages--; + target_hstate->max_huge_pages += + pages_per_huge_page(h) / pages_per_huge_page(target_hstate); + + return rc; +} + +static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed) + __must_hold(&hugetlb_lock) +{ + int nr_nodes, node; + struct page *page; + + lockdep_assert_held(&hugetlb_lock); + + /* We should never get here if no demote order */ + if (!h->demote_order) { + pr_warn("HugeTLB: NULL demote order passed to demote_pool_huge_page.\n"); + return -EINVAL; /* internal error */ + } + + for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { + list_for_each_entry(page, &h->hugepage_freelists[node], lru) { + if (PageHWPoison(page)) + continue; + + return demote_free_huge_page(h, page); + } + } + + /* + * Only way to get here is if all pages on free lists are poisoned. + * Return -EBUSY so that caller will not retry. + */ + return -EBUSY; +} + +#define HSTATE_ATTR_RO(_name) \ + static struct kobj_attribute _name##_attr = __ATTR_RO(_name) + +#define HSTATE_ATTR_WO(_name) \ + static struct kobj_attribute _name##_attr = __ATTR_WO(_name) + +#define HSTATE_ATTR(_name) \ + static struct kobj_attribute _name##_attr = __ATTR_RW(_name) + +static struct kobject *hugepages_kobj; +static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; + +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); + +static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) +{ + int i; + + for (i = 0; i < HUGE_MAX_HSTATE; i++) + if (hstate_kobjs[i] == kobj) { + if (nidp) + *nidp = NUMA_NO_NODE; + return &hstates[i]; + } + + return kobj_to_node_hstate(kobj, nidp); +} + +static ssize_t nr_hugepages_show_common(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long nr_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + nr_huge_pages = h->nr_huge_pages; + else + nr_huge_pages = h->nr_huge_pages_node[nid]; + + return sysfs_emit(buf, "%lu\n", nr_huge_pages); +} + +static ssize_t __nr_hugepages_store_common(bool obey_mempolicy, + struct hstate *h, int nid, + unsigned long count, size_t len) +{ + int err; + nodemask_t nodes_allowed, *n_mask; + + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) + return -EINVAL; + + if (nid == NUMA_NO_NODE) { + /* + * global hstate attribute + */ + if (!(obey_mempolicy && + init_nodemask_of_mempolicy(&nodes_allowed))) + n_mask = &node_states[N_MEMORY]; + else + n_mask = &nodes_allowed; + } else { + /* + * Node specific request. count adjustment happens in + * set_max_huge_pages() after acquiring hugetlb_lock. + */ + init_nodemask_of_node(&nodes_allowed, nid); + n_mask = &nodes_allowed; + } + + err = set_max_huge_pages(h, count, nid, n_mask); + + return err ? err : len; +} + +static ssize_t nr_hugepages_store_common(bool obey_mempolicy, + struct kobject *kobj, const char *buf, + size_t len) +{ + struct hstate *h; + unsigned long count; + int nid; + int err; + + err = kstrtoul(buf, 10, &count); + if (err) + return err; + + h = kobj_to_hstate(kobj, &nid); + return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len); +} + +static ssize_t nr_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return nr_hugepages_show_common(kobj, attr, buf); +} + +static ssize_t nr_hugepages_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t len) +{ + return nr_hugepages_store_common(false, kobj, buf, len); +} +HSTATE_ATTR(nr_hugepages); + +#ifdef CONFIG_NUMA + +/* + * hstate attribute for optionally mempolicy-based constraint on persistent + * huge page alloc/free. + */ +static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return nr_hugepages_show_common(kobj, attr, buf); +} + +static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t len) +{ + return nr_hugepages_store_common(true, kobj, buf, len); +} +HSTATE_ATTR(nr_hugepages_mempolicy); +#endif + + +static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj, NULL); + return sysfs_emit(buf, "%lu\n", h->nr_overcommit_huge_pages); +} + +static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + int err; + unsigned long input; + struct hstate *h = kobj_to_hstate(kobj, NULL); + + if (hstate_is_gigantic(h)) + return -EINVAL; + + err = kstrtoul(buf, 10, &input); + if (err) + return err; + + spin_lock_irq(&hugetlb_lock); + h->nr_overcommit_huge_pages = input; + spin_unlock_irq(&hugetlb_lock); + + return count; +} +HSTATE_ATTR(nr_overcommit_hugepages); + +static ssize_t free_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long free_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + free_huge_pages = h->free_huge_pages; + else + free_huge_pages = h->free_huge_pages_node[nid]; + + return sysfs_emit(buf, "%lu\n", free_huge_pages); +} +HSTATE_ATTR_RO(free_hugepages); + +static ssize_t resv_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj, NULL); + return sysfs_emit(buf, "%lu\n", h->resv_huge_pages); +} +HSTATE_ATTR_RO(resv_hugepages); + +static ssize_t surplus_hugepages_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h; + unsigned long surplus_huge_pages; + int nid; + + h = kobj_to_hstate(kobj, &nid); + if (nid == NUMA_NO_NODE) + surplus_huge_pages = h->surplus_huge_pages; + else + surplus_huge_pages = h->surplus_huge_pages_node[nid]; + + return sysfs_emit(buf, "%lu\n", surplus_huge_pages); +} +HSTATE_ATTR_RO(surplus_hugepages); + +static ssize_t demote_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t len) +{ + unsigned long nr_demote; + unsigned long nr_available; + nodemask_t nodes_allowed, *n_mask; + struct hstate *h; + int err; + int nid; + + err = kstrtoul(buf, 10, &nr_demote); + if (err) + return err; + h = kobj_to_hstate(kobj, &nid); + + if (nid != NUMA_NO_NODE) { + init_nodemask_of_node(&nodes_allowed, nid); + n_mask = &nodes_allowed; + } else { + n_mask = &node_states[N_MEMORY]; + } + + /* Synchronize with other sysfs operations modifying huge pages */ + mutex_lock(&h->resize_lock); + spin_lock_irq(&hugetlb_lock); + + while (nr_demote) { + /* + * Check for available pages to demote each time thorough the + * loop as demote_pool_huge_page will drop hugetlb_lock. + */ + if (nid != NUMA_NO_NODE) + nr_available = h->free_huge_pages_node[nid]; + else + nr_available = h->free_huge_pages; + nr_available -= h->resv_huge_pages; + if (!nr_available) + break; + + err = demote_pool_huge_page(h, n_mask); + if (err) + break; + + nr_demote--; + } + + spin_unlock_irq(&hugetlb_lock); + mutex_unlock(&h->resize_lock); + + if (err) + return err; + return len; +} +HSTATE_ATTR_WO(demote); + +static ssize_t demote_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct hstate *h = kobj_to_hstate(kobj, NULL); + unsigned long demote_size = (PAGE_SIZE << h->demote_order) / SZ_1K; + + return sysfs_emit(buf, "%lukB\n", demote_size); +} + +static ssize_t demote_size_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct hstate *h, *demote_hstate; + unsigned long demote_size; + unsigned int demote_order; + + demote_size = (unsigned long)memparse(buf, NULL); + + demote_hstate = size_to_hstate(demote_size); + if (!demote_hstate) + return -EINVAL; + demote_order = demote_hstate->order; + if (demote_order < HUGETLB_PAGE_ORDER) + return -EINVAL; + + /* demote order must be smaller than hstate order */ + h = kobj_to_hstate(kobj, NULL); + if (demote_order >= h->order) + return -EINVAL; + + /* resize_lock synchronizes access to demote size and writes */ + mutex_lock(&h->resize_lock); + h->demote_order = demote_order; + mutex_unlock(&h->resize_lock); + + return count; +} +HSTATE_ATTR(demote_size); + +static struct attribute *hstate_attrs[] = { + &nr_hugepages_attr.attr, + &nr_overcommit_hugepages_attr.attr, + &free_hugepages_attr.attr, + &resv_hugepages_attr.attr, + &surplus_hugepages_attr.attr, +#ifdef CONFIG_NUMA + &nr_hugepages_mempolicy_attr.attr, +#endif + NULL, +}; + +static const struct attribute_group hstate_attr_group = { + .attrs = hstate_attrs, +}; + +static struct attribute *hstate_demote_attrs[] = { + &demote_size_attr.attr, + &demote_attr.attr, + NULL, +}; + +static const struct attribute_group hstate_demote_attr_group = { + .attrs = hstate_demote_attrs, +}; + +static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, + struct kobject **hstate_kobjs, + const struct attribute_group *hstate_attr_group) +{ + int retval; + int hi = hstate_index(h); + + hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); + if (!hstate_kobjs[hi]) + return -ENOMEM; + + retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); + if (retval) { + kobject_put(hstate_kobjs[hi]); + hstate_kobjs[hi] = NULL; + return retval; + } + + if (h->demote_order) { + retval = sysfs_create_group(hstate_kobjs[hi], + &hstate_demote_attr_group); + if (retval) { + pr_warn("HugeTLB unable to create demote interfaces for %s\n", h->name); + sysfs_remove_group(hstate_kobjs[hi], hstate_attr_group); + kobject_put(hstate_kobjs[hi]); + hstate_kobjs[hi] = NULL; + return retval; + } + } + + return 0; +} + +#ifdef CONFIG_NUMA +static bool hugetlb_sysfs_initialized __ro_after_init; + +/* + * node_hstate/s - associate per node hstate attributes, via their kobjects, + * with node devices in node_devices[] using a parallel array. The array + * index of a node device or _hstate == node id. + * This is here to avoid any static dependency of the node device driver, in + * the base kernel, on the hugetlb module. + */ +struct node_hstate { + struct kobject *hugepages_kobj; + struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; +}; +static struct node_hstate node_hstates[MAX_NUMNODES]; + +/* + * A subset of global hstate attributes for node devices + */ +static struct attribute *per_node_hstate_attrs[] = { + &nr_hugepages_attr.attr, + &free_hugepages_attr.attr, + &surplus_hugepages_attr.attr, + NULL, +}; + +static const struct attribute_group per_node_hstate_attr_group = { + .attrs = per_node_hstate_attrs, +}; + +/* + * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. + * Returns node id via non-NULL nidp. + */ +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) +{ + int nid; + + for (nid = 0; nid < nr_node_ids; nid++) { + struct node_hstate *nhs = &node_hstates[nid]; + int i; + for (i = 0; i < HUGE_MAX_HSTATE; i++) + if (nhs->hstate_kobjs[i] == kobj) { + if (nidp) + *nidp = nid; + return &hstates[i]; + } + } + + BUG(); + return NULL; +} + +/* + * Unregister hstate attributes from a single node device. + * No-op if no hstate attributes attached. + */ +void hugetlb_unregister_node(struct node *node) +{ + struct hstate *h; + struct node_hstate *nhs = &node_hstates[node->dev.id]; + + if (!nhs->hugepages_kobj) + return; /* no hstate attributes */ + + for_each_hstate(h) { + int idx = hstate_index(h); + struct kobject *hstate_kobj = nhs->hstate_kobjs[idx]; + + if (!hstate_kobj) + continue; + if (h->demote_order) + sysfs_remove_group(hstate_kobj, &hstate_demote_attr_group); + sysfs_remove_group(hstate_kobj, &per_node_hstate_attr_group); + kobject_put(hstate_kobj); + nhs->hstate_kobjs[idx] = NULL; + } + + kobject_put(nhs->hugepages_kobj); + nhs->hugepages_kobj = NULL; +} + + +/* + * Register hstate attributes for a single node device. + * No-op if attributes already registered. + */ +void hugetlb_register_node(struct node *node) +{ + struct hstate *h; + struct node_hstate *nhs = &node_hstates[node->dev.id]; + int err; + + if (!hugetlb_sysfs_initialized) + return; + + if (nhs->hugepages_kobj) + return; /* already allocated */ + + nhs->hugepages_kobj = kobject_create_and_add("hugepages", + &node->dev.kobj); + if (!nhs->hugepages_kobj) + return; + + for_each_hstate(h) { + err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, + nhs->hstate_kobjs, + &per_node_hstate_attr_group); + if (err) { + pr_err("HugeTLB: Unable to add hstate %s for node %d\n", + h->name, node->dev.id); + hugetlb_unregister_node(node); + break; + } + } +} + +/* + * hugetlb init time: register hstate attributes for all registered node + * devices of nodes that have memory. All on-line nodes should have + * registered their associated device by this time. + */ +static void __init hugetlb_register_all_nodes(void) +{ + int nid; + + for_each_online_node(nid) + hugetlb_register_node(node_devices[nid]); +} +#else /* !CONFIG_NUMA */ + +static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) +{ + BUG(); + if (nidp) + *nidp = -1; + return NULL; +} + +static void hugetlb_register_all_nodes(void) { } + +#endif + +#ifdef CONFIG_CMA +static void __init hugetlb_cma_check(void); +#else +static inline __init void hugetlb_cma_check(void) +{ +} +#endif + +static void __init hugetlb_sysfs_init(void) +{ + struct hstate *h; + int err; + + hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); + if (!hugepages_kobj) + return; + + for_each_hstate(h) { + err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, + hstate_kobjs, &hstate_attr_group); + if (err) + pr_err("HugeTLB: Unable to add hstate %s", h->name); + } + +#ifdef CONFIG_NUMA + hugetlb_sysfs_initialized = true; +#endif + hugetlb_register_all_nodes(); +} + +static int __init hugetlb_init(void) +{ + int i; + + BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE < + __NR_HPAGEFLAGS); + + if (!hugepages_supported()) { + if (hugetlb_max_hstate || default_hstate_max_huge_pages) + pr_warn("HugeTLB: huge pages not supported, ignoring associated command-line parameters\n"); + return 0; + } + + /* + * Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists. Some + * architectures depend on setup being done here. + */ + hugetlb_add_hstate(HUGETLB_PAGE_ORDER); + if (!parsed_default_hugepagesz) { + /* + * If we did not parse a default huge page size, set + * default_hstate_idx to HPAGE_SIZE hstate. And, if the + * number of huge pages for this default size was implicitly + * specified, set that here as well. + * Note that the implicit setting will overwrite an explicit + * setting. A warning will be printed in this case. + */ + default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE)); + if (default_hstate_max_huge_pages) { + if (default_hstate.max_huge_pages) { + char buf[32]; + + string_get_size(huge_page_size(&default_hstate), + 1, STRING_UNITS_2, buf, 32); + pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n", + default_hstate.max_huge_pages, buf); + pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n", + default_hstate_max_huge_pages); + } + default_hstate.max_huge_pages = + default_hstate_max_huge_pages; + + for_each_online_node(i) + default_hstate.max_huge_pages_node[i] = + default_hugepages_in_node[i]; + } + } + + hugetlb_cma_check(); + hugetlb_init_hstates(); + gather_bootmem_prealloc(); + report_hugepages(); + + hugetlb_sysfs_init(); + hugetlb_cgroup_file_init(); + +#ifdef CONFIG_SMP + num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus()); +#else + num_fault_mutexes = 1; +#endif + hugetlb_fault_mutex_table = + kmalloc_array(num_fault_mutexes, sizeof(struct mutex), + GFP_KERNEL); + BUG_ON(!hugetlb_fault_mutex_table); + + for (i = 0; i < num_fault_mutexes; i++) + mutex_init(&hugetlb_fault_mutex_table[i]); + return 0; +} +subsys_initcall(hugetlb_init); + +/* Overwritten by architectures with more huge page sizes */ +bool __init __attribute((weak)) arch_hugetlb_valid_size(unsigned long size) +{ + return size == HPAGE_SIZE; +} + +void __init hugetlb_add_hstate(unsigned int order) +{ + struct hstate *h; + unsigned long i; + + if (size_to_hstate(PAGE_SIZE << order)) { + return; + } + BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); + BUG_ON(order == 0); + h = &hstates[hugetlb_max_hstate++]; + mutex_init(&h->resize_lock); + h->order = order; + h->mask = ~(huge_page_size(h) - 1); + for (i = 0; i < MAX_NUMNODES; ++i) + INIT_LIST_HEAD(&h->hugepage_freelists[i]); + INIT_LIST_HEAD(&h->hugepage_activelist); + h->next_nid_to_alloc = first_memory_node; + h->next_nid_to_free = first_memory_node; + snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", + huge_page_size(h)/SZ_1K); + + parsed_hstate = h; +} + +bool __init __weak hugetlb_node_alloc_supported(void) +{ + return true; +} + +static void __init hugepages_clear_pages_in_node(void) +{ + if (!hugetlb_max_hstate) { + default_hstate_max_huge_pages = 0; + memset(default_hugepages_in_node, 0, + sizeof(default_hugepages_in_node)); + } else { + parsed_hstate->max_huge_pages = 0; + memset(parsed_hstate->max_huge_pages_node, 0, + sizeof(parsed_hstate->max_huge_pages_node)); + } +} + +/* + * hugepages command line processing + * hugepages normally follows a valid hugepagsz or default_hugepagsz + * specification. If not, ignore the hugepages value. hugepages can also + * be the first huge page command line option in which case it implicitly + * specifies the number of huge pages for the default size. + */ +static int __init hugepages_setup(char *s) +{ + unsigned long *mhp; + static unsigned long *last_mhp; + int node = NUMA_NO_NODE; + int count; + unsigned long tmp; + char *p = s; + + if (!parsed_valid_hugepagesz) { + pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s); + parsed_valid_hugepagesz = true; + return 1; + } + + /* + * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter + * yet, so this hugepages= parameter goes to the "default hstate". + * Otherwise, it goes with the previously parsed hugepagesz or + * default_hugepagesz. + */ + else if (!hugetlb_max_hstate) + mhp = &default_hstate_max_huge_pages; + else + mhp = &parsed_hstate->max_huge_pages; + + if (mhp == last_mhp) { + pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s); + return 1; + } + + while (*p) { + count = 0; + if (sscanf(p, "%lu%n", &tmp, &count) != 1) + goto invalid; + /* Parameter is node format */ + if (p[count] == ':') { + if (!hugetlb_node_alloc_supported()) { + pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n"); + return 1; + } + if (tmp >= MAX_NUMNODES || !node_online(tmp)) + goto invalid; + node = array_index_nospec(tmp, MAX_NUMNODES); + p += count + 1; + /* Parse hugepages */ + if (sscanf(p, "%lu%n", &tmp, &count) != 1) + goto invalid; + if (!hugetlb_max_hstate) + default_hugepages_in_node[node] = tmp; + else + parsed_hstate->max_huge_pages_node[node] = tmp; + *mhp += tmp; + /* Go to parse next node*/ + if (p[count] == ',') + p += count + 1; + else + break; + } else { + if (p != s) + goto invalid; + *mhp = tmp; + break; + } + } + + /* + * Global state is always initialized later in hugetlb_init. + * But we need to allocate gigantic hstates here early to still + * use the bootmem allocator. + */ + if (hugetlb_max_hstate && hstate_is_gigantic(parsed_hstate)) + hugetlb_hstate_alloc_pages(parsed_hstate); + + last_mhp = mhp; + + return 1; + +invalid: + pr_warn("HugeTLB: Invalid hugepages parameter %s\n", p); + hugepages_clear_pages_in_node(); + return 1; +} +__setup("hugepages=", hugepages_setup); + +/* + * hugepagesz command line processing + * A specific huge page size can only be specified once with hugepagesz. + * hugepagesz is followed by hugepages on the command line. The global + * variable 'parsed_valid_hugepagesz' is used to determine if prior + * hugepagesz argument was valid. + */ +static int __init hugepagesz_setup(char *s) +{ + unsigned long size; + struct hstate *h; + + parsed_valid_hugepagesz = false; + size = (unsigned long)memparse(s, NULL); + + if (!arch_hugetlb_valid_size(size)) { + pr_err("HugeTLB: unsupported hugepagesz=%s\n", s); + return 1; + } + + h = size_to_hstate(size); + if (h) { + /* + * hstate for this size already exists. This is normally + * an error, but is allowed if the existing hstate is the + * default hstate. More specifically, it is only allowed if + * the number of huge pages for the default hstate was not + * previously specified. + */ + if (!parsed_default_hugepagesz || h != &default_hstate || + default_hstate.max_huge_pages) { + pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s); + return 1; + } + + /* + * No need to call hugetlb_add_hstate() as hstate already + * exists. But, do set parsed_hstate so that a following + * hugepages= parameter will be applied to this hstate. + */ + parsed_hstate = h; + parsed_valid_hugepagesz = true; + return 1; + } + + hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT); + parsed_valid_hugepagesz = true; + return 1; +} +__setup("hugepagesz=", hugepagesz_setup); + +/* + * default_hugepagesz command line input + * Only one instance of default_hugepagesz allowed on command line. + */ +static int __init default_hugepagesz_setup(char *s) +{ + unsigned long size; + int i; + + parsed_valid_hugepagesz = false; + if (parsed_default_hugepagesz) { + pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s); + return 1; + } + + size = (unsigned long)memparse(s, NULL); + + if (!arch_hugetlb_valid_size(size)) { + pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s); + return 1; + } + + hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT); + parsed_valid_hugepagesz = true; + parsed_default_hugepagesz = true; + default_hstate_idx = hstate_index(size_to_hstate(size)); + + /* + * The number of default huge pages (for this size) could have been + * specified as the first hugetlb parameter: hugepages=X. If so, + * then default_hstate_max_huge_pages is set. If the default huge + * page size is gigantic (>= MAX_ORDER), then the pages must be + * allocated here from bootmem allocator. + */ + if (default_hstate_max_huge_pages) { + default_hstate.max_huge_pages = default_hstate_max_huge_pages; + for_each_online_node(i) + default_hstate.max_huge_pages_node[i] = + default_hugepages_in_node[i]; + if (hstate_is_gigantic(&default_hstate)) + hugetlb_hstate_alloc_pages(&default_hstate); + default_hstate_max_huge_pages = 0; + } + + return 1; +} +__setup("default_hugepagesz=", default_hugepagesz_setup); + +static nodemask_t *policy_mbind_nodemask(gfp_t gfp) +{ +#ifdef CONFIG_NUMA + struct mempolicy *mpol = get_task_policy(current); + + /* + * Only enforce MPOL_BIND policy which overlaps with cpuset policy + * (from policy_nodemask) specifically for hugetlb case + */ + if (mpol->mode == MPOL_BIND && + (apply_policy_zone(mpol, gfp_zone(gfp)) && + cpuset_nodemask_valid_mems_allowed(&mpol->nodes))) + return &mpol->nodes; +#endif + return NULL; +} + +static unsigned int allowed_mems_nr(struct hstate *h) +{ + int node; + unsigned int nr = 0; + nodemask_t *mbind_nodemask; + unsigned int *array = h->free_huge_pages_node; + gfp_t gfp_mask = htlb_alloc_mask(h); + + mbind_nodemask = policy_mbind_nodemask(gfp_mask); + for_each_node_mask(node, cpuset_current_mems_allowed) { + if (!mbind_nodemask || node_isset(node, *mbind_nodemask)) + nr += array[node]; + } + + return nr; +} + +#ifdef CONFIG_SYSCTL +static int proc_hugetlb_doulongvec_minmax(struct ctl_table *table, int write, + void *buffer, size_t *length, + loff_t *ppos, unsigned long *out) +{ + struct ctl_table dup_table; + + /* + * In order to avoid races with __do_proc_doulongvec_minmax(), we + * can duplicate the @table and alter the duplicate of it. + */ + dup_table = *table; + dup_table.data = out; + + return proc_doulongvec_minmax(&dup_table, write, buffer, length, ppos); +} + +static int hugetlb_sysctl_handler_common(bool obey_mempolicy, + struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp = h->max_huge_pages; + int ret; + + if (!hugepages_supported()) + return -EOPNOTSUPP; + + ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos, + &tmp); + if (ret) + goto out; + + if (write) + ret = __nr_hugepages_store_common(obey_mempolicy, h, + NUMA_NO_NODE, tmp, *length); +out: + return ret; +} + +int hugetlb_sysctl_handler(struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) +{ + + return hugetlb_sysctl_handler_common(false, table, write, + buffer, length, ppos); +} + +#ifdef CONFIG_NUMA +int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) +{ + return hugetlb_sysctl_handler_common(true, table, write, + buffer, length, ppos); +} +#endif /* CONFIG_NUMA */ + +int hugetlb_overcommit_handler(struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) +{ + struct hstate *h = &default_hstate; + unsigned long tmp; + int ret; + + if (!hugepages_supported()) + return -EOPNOTSUPP; + + tmp = h->nr_overcommit_huge_pages; + + if (write && hstate_is_gigantic(h)) + return -EINVAL; + + ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos, + &tmp); + if (ret) + goto out; + + if (write) { + spin_lock_irq(&hugetlb_lock); + h->nr_overcommit_huge_pages = tmp; + spin_unlock_irq(&hugetlb_lock); + } +out: + return ret; +} + +#endif /* CONFIG_SYSCTL */ + +void hugetlb_report_meminfo(struct seq_file *m) +{ + struct hstate *h; + unsigned long total = 0; + + if (!hugepages_supported()) + return; + + for_each_hstate(h) { + unsigned long count = h->nr_huge_pages; + + total += huge_page_size(h) * count; + + if (h == &default_hstate) + seq_printf(m, + "HugePages_Total: %5lu\n" + "HugePages_Free: %5lu\n" + "HugePages_Rsvd: %5lu\n" + "HugePages_Surp: %5lu\n" + "Hugepagesize: %8lu kB\n", + count, + h->free_huge_pages, + h->resv_huge_pages, + h->surplus_huge_pages, + huge_page_size(h) / SZ_1K); + } + + seq_printf(m, "Hugetlb: %8lu kB\n", total / SZ_1K); +} + +int hugetlb_report_node_meminfo(char *buf, int len, int nid) +{ + struct hstate *h = &default_hstate; + + if (!hugepages_supported()) + return 0; + + return sysfs_emit_at(buf, len, + "Node %d HugePages_Total: %5u\n" + "Node %d HugePages_Free: %5u\n" + "Node %d HugePages_Surp: %5u\n", + nid, h->nr_huge_pages_node[nid], + nid, h->free_huge_pages_node[nid], + nid, h->surplus_huge_pages_node[nid]); +} + +void hugetlb_show_meminfo_node(int nid) +{ + struct hstate *h; + + if (!hugepages_supported()) + return; + + for_each_hstate(h) + printk("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n", + nid, + h->nr_huge_pages_node[nid], + h->free_huge_pages_node[nid], + h->surplus_huge_pages_node[nid], + huge_page_size(h) / SZ_1K); +} + +void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm) +{ + seq_printf(m, "HugetlbPages:\t%8lu kB\n", + atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10)); +} + +/* Return the number pages of memory we physically have, in PAGE_SIZE units. */ +unsigned long hugetlb_total_pages(void) +{ + struct hstate *h; + unsigned long nr_total_pages = 0; + + for_each_hstate(h) + nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h); + return nr_total_pages; +} + +static int hugetlb_acct_memory(struct hstate *h, long delta) +{ + int ret = -ENOMEM; + + if (!delta) + return 0; + + spin_lock_irq(&hugetlb_lock); + /* + * When cpuset is configured, it breaks the strict hugetlb page + * reservation as the accounting is done on a global variable. Such + * reservation is completely rubbish in the presence of cpuset because + * the reservation is not checked against page availability for the + * current cpuset. Application can still potentially OOM'ed by kernel + * with lack of free htlb page in cpuset that the task is in. + * Attempt to enforce strict accounting with cpuset is almost + * impossible (or too ugly) because cpuset is too fluid that + * task or memory node can be dynamically moved between cpusets. + * + * The change of semantics for shared hugetlb mapping with cpuset is + * undesirable. However, in order to preserve some of the semantics, + * we fall back to check against current free page availability as + * a best attempt and hopefully to minimize the impact of changing + * semantics that cpuset has. + * + * Apart from cpuset, we also have memory policy mechanism that + * also determines from which node the kernel will allocate memory + * in a NUMA system. So similar to cpuset, we also should consider + * the memory policy of the current task. Similar to the description + * above. + */ + if (delta > 0) { + if (gather_surplus_pages(h, delta) < 0) + goto out; + + if (delta > allowed_mems_nr(h)) { + return_unused_surplus_pages(h, delta); + goto out; + } + } + + ret = 0; + if (delta < 0) + return_unused_surplus_pages(h, (unsigned long) -delta); + +out: + spin_unlock_irq(&hugetlb_lock); + return ret; +} + +static void hugetlb_vm_op_open(struct vm_area_struct *vma) +{ + struct resv_map *resv = vma_resv_map(vma); + + /* + * HPAGE_RESV_OWNER indicates a private mapping. + * This new VMA should share its siblings reservation map if present. + * The VMA will only ever have a valid reservation map pointer where + * it is being copied for another still existing VMA. As that VMA + * has a reference to the reservation map it cannot disappear until + * after this open call completes. It is therefore safe to take a + * new reference here without additional locking. + */ + if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + resv_map_dup_hugetlb_cgroup_uncharge_info(resv); + kref_get(&resv->refs); + } + + /* + * vma_lock structure for sharable mappings is vma specific. + * Clear old pointer (if copied via vm_area_dup) and allocate + * new structure. Before clearing, make sure vma_lock is not + * for this vma. + */ + if (vma->vm_flags & VM_MAYSHARE) { + struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; + + if (vma_lock) { + if (vma_lock->vma != vma) { + vma->vm_private_data = NULL; + hugetlb_vma_lock_alloc(vma); + } else + pr_warn("HugeTLB: vma_lock already exists in %s.\n", __func__); + } else + hugetlb_vma_lock_alloc(vma); + } +} + +static void hugetlb_vm_op_close(struct vm_area_struct *vma) +{ + struct hstate *h = hstate_vma(vma); + struct resv_map *resv; + struct hugepage_subpool *spool = subpool_vma(vma); + unsigned long reserve, start, end; + long gbl_reserve; + + hugetlb_vma_lock_free(vma); + + resv = vma_resv_map(vma); + if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + return; + + start = vma_hugecache_offset(h, vma, vma->vm_start); + end = vma_hugecache_offset(h, vma, vma->vm_end); + + reserve = (end - start) - region_count(resv, start, end); + hugetlb_cgroup_uncharge_counter(resv, start, end); + if (reserve) { + /* + * Decrement reserve counts. The global reserve count may be + * adjusted if the subpool has a minimum size. + */ + gbl_reserve = hugepage_subpool_put_pages(spool, reserve); + hugetlb_acct_memory(h, -gbl_reserve); + } + + kref_put(&resv->refs, resv_map_release); +} + +static int hugetlb_vm_op_split(struct vm_area_struct *vma, unsigned long addr) +{ + if (addr & ~(huge_page_mask(hstate_vma(vma)))) + return -EINVAL; + + /* + * PMD sharing is only possible for PUD_SIZE-aligned address ranges + * in HugeTLB VMAs. If we will lose PUD_SIZE alignment due to this + * split, unshare PMDs in the PUD_SIZE interval surrounding addr now. + */ + if (addr & ~PUD_MASK) { + /* + * hugetlb_vm_op_split is called right before we attempt to + * split the VMA. We will need to unshare PMDs in the old and + * new VMAs, so let's unshare before we split. + */ + unsigned long floor = addr & PUD_MASK; + unsigned long ceil = floor + PUD_SIZE; + + if (floor >= vma->vm_start && ceil <= vma->vm_end) + hugetlb_unshare_pmds(vma, floor, ceil); + } + + return 0; +} + +static unsigned long hugetlb_vm_op_pagesize(struct vm_area_struct *vma) +{ + return huge_page_size(hstate_vma(vma)); +} + +/* + * We cannot handle pagefaults against hugetlb pages at all. They cause + * handle_mm_fault() to try to instantiate regular-sized pages in the + * hugepage VMA. do_page_fault() is supposed to trap this, so BUG is we get + * this far. + */ +static vm_fault_t hugetlb_vm_op_fault(struct vm_fault *vmf) +{ + BUG(); + return 0; +} + +/* + * When a new function is introduced to vm_operations_struct and added + * to hugetlb_vm_ops, please consider adding the function to shm_vm_ops. + * This is because under System V memory model, mappings created via + * shmget/shmat with "huge page" specified are backed by hugetlbfs files, + * their original vm_ops are overwritten with shm_vm_ops. + */ +const struct vm_operations_struct hugetlb_vm_ops = { + .fault = hugetlb_vm_op_fault, + .open = hugetlb_vm_op_open, + .close = hugetlb_vm_op_close, + .may_split = hugetlb_vm_op_split, + .pagesize = hugetlb_vm_op_pagesize, +}; + +static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, + int writable) +{ + pte_t entry; + unsigned int shift = huge_page_shift(hstate_vma(vma)); + + if (writable) { + entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page, + vma->vm_page_prot))); + } else { + entry = huge_pte_wrprotect(mk_huge_pte(page, + vma->vm_page_prot)); + } + entry = pte_mkyoung(entry); + entry = arch_make_huge_pte(entry, shift, vma->vm_flags); + + return entry; +} + +static void set_huge_ptep_writable(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep) +{ + pte_t entry; + + entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep))); + if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) + update_mmu_cache(vma, address, ptep); +} + +bool is_hugetlb_entry_migration(pte_t pte) +{ + swp_entry_t swp; + + if (huge_pte_none(pte) || pte_present(pte)) + return false; + swp = pte_to_swp_entry(pte); + if (is_migration_entry(swp)) + return true; + else + return false; +} + +static bool is_hugetlb_entry_hwpoisoned(pte_t pte) +{ + swp_entry_t swp; + + if (huge_pte_none(pte) || pte_present(pte)) + return false; + swp = pte_to_swp_entry(pte); + if (is_hwpoison_entry(swp)) + return true; + else + return false; +} + +static void +hugetlb_install_page(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr, + struct page *new_page) +{ + __SetPageUptodate(new_page); + hugepage_add_new_anon_rmap(new_page, vma, addr); + set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1)); + hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm); + ClearHPageRestoreReserve(new_page); + SetHPageMigratable(new_page); +} + +int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, + struct vm_area_struct *dst_vma, + struct vm_area_struct *src_vma) +{ + pte_t *src_pte, *dst_pte, entry; + struct page *ptepage; + unsigned long addr; + bool cow = is_cow_mapping(src_vma->vm_flags); + struct hstate *h = hstate_vma(src_vma); + unsigned long sz = huge_page_size(h); + unsigned long npages = pages_per_huge_page(h); + struct mmu_notifier_range range; + unsigned long last_addr_mask; + int ret = 0; + + if (cow) { + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, src_vma, src, + src_vma->vm_start, + src_vma->vm_end); + mmu_notifier_invalidate_range_start(&range); + mmap_assert_write_locked(src); + raw_write_seqcount_begin(&src->write_protect_seq); + } else { + /* + * For shared mappings the vma lock must be held before + * calling huge_pte_offset in the src vma. Otherwise, the + * returned ptep could go away if part of a shared pmd and + * another thread calls huge_pmd_unshare. + */ + hugetlb_vma_lock_read(src_vma); + } + + last_addr_mask = hugetlb_mask_last_page(h); + for (addr = src_vma->vm_start; addr < src_vma->vm_end; addr += sz) { + spinlock_t *src_ptl, *dst_ptl; + src_pte = huge_pte_offset(src, addr, sz); + if (!src_pte) { + addr |= last_addr_mask; + continue; + } + dst_pte = huge_pte_alloc(dst, dst_vma, addr, sz); + if (!dst_pte) { + ret = -ENOMEM; + break; + } + + /* + * If the pagetables are shared don't copy or take references. + * + * dst_pte == src_pte is the common case of src/dest sharing. + * However, src could have 'unshared' and dst shares with + * another vma. So page_count of ptep page is checked instead + * to reliably determine whether pte is shared. + */ + if (page_count(virt_to_page(dst_pte)) > 1) { + addr |= last_addr_mask; + continue; + } + + dst_ptl = huge_pte_lock(h, dst, dst_pte); + src_ptl = huge_pte_lockptr(h, src, src_pte); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + entry = huge_ptep_get(src_pte); +again: + if (huge_pte_none(entry)) { + /* + * Skip if src entry none. + */ + ; + } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) { + bool uffd_wp = huge_pte_uffd_wp(entry); + + if (!userfaultfd_wp(dst_vma) && uffd_wp) + entry = huge_pte_clear_uffd_wp(entry); + set_huge_pte_at(dst, addr, dst_pte, entry); + } else if (unlikely(is_hugetlb_entry_migration(entry))) { + swp_entry_t swp_entry = pte_to_swp_entry(entry); + bool uffd_wp = huge_pte_uffd_wp(entry); + + if (!is_readable_migration_entry(swp_entry) && cow) { + /* + * COW mappings require pages in both + * parent and child to be set to read. + */ + swp_entry = make_readable_migration_entry( + swp_offset(swp_entry)); + entry = swp_entry_to_pte(swp_entry); + if (userfaultfd_wp(src_vma) && uffd_wp) + entry = huge_pte_mkuffd_wp(entry); + set_huge_pte_at(src, addr, src_pte, entry); + } + if (!userfaultfd_wp(dst_vma) && uffd_wp) + entry = huge_pte_clear_uffd_wp(entry); + set_huge_pte_at(dst, addr, dst_pte, entry); + } else if (unlikely(is_pte_marker(entry))) { + /* + * We copy the pte marker only if the dst vma has + * uffd-wp enabled. + */ + if (userfaultfd_wp(dst_vma)) + set_huge_pte_at(dst, addr, dst_pte, entry); + } else { + entry = huge_ptep_get(src_pte); + ptepage = pte_page(entry); + get_page(ptepage); + + /* + * Failing to duplicate the anon rmap is a rare case + * where we see pinned hugetlb pages while they're + * prone to COW. We need to do the COW earlier during + * fork. + * + * When pre-allocating the page or copying data, we + * need to be without the pgtable locks since we could + * sleep during the process. + */ + if (!PageAnon(ptepage)) { + page_dup_file_rmap(ptepage, true); + } else if (page_try_dup_anon_rmap(ptepage, true, + src_vma)) { + pte_t src_pte_old = entry; + struct page *new; + + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + /* Do not use reserve as it's private owned */ + new = alloc_huge_page(dst_vma, addr, 1); + if (IS_ERR(new)) { + put_page(ptepage); + ret = PTR_ERR(new); + break; + } + copy_user_huge_page(new, ptepage, addr, dst_vma, + npages); + put_page(ptepage); + + /* Install the new huge page if src pte stable */ + dst_ptl = huge_pte_lock(h, dst, dst_pte); + src_ptl = huge_pte_lockptr(h, src, src_pte); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + entry = huge_ptep_get(src_pte); + if (!pte_same(src_pte_old, entry)) { + restore_reserve_on_error(h, dst_vma, addr, + new); + put_page(new); + /* huge_ptep of dst_pte won't change as in child */ + goto again; + } + hugetlb_install_page(dst_vma, dst_pte, addr, new); + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + continue; + } + + if (cow) { + /* + * No need to notify as we are downgrading page + * table protection not changing it to point + * to a new page. + * + * See Documentation/mm/mmu_notifier.rst + */ + huge_ptep_set_wrprotect(src, addr, src_pte); + entry = huge_pte_wrprotect(entry); + } + + set_huge_pte_at(dst, addr, dst_pte, entry); + hugetlb_count_add(npages, dst); + } + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + } + + if (cow) { + raw_write_seqcount_end(&src->write_protect_seq); + mmu_notifier_invalidate_range_end(&range); + } else { + hugetlb_vma_unlock_read(src_vma); + } + + return ret; +} + +static void move_huge_pte(struct vm_area_struct *vma, unsigned long old_addr, + unsigned long new_addr, pte_t *src_pte, pte_t *dst_pte) +{ + struct hstate *h = hstate_vma(vma); + struct mm_struct *mm = vma->vm_mm; + spinlock_t *src_ptl, *dst_ptl; + pte_t pte; + + dst_ptl = huge_pte_lock(h, mm, dst_pte); + src_ptl = huge_pte_lockptr(h, mm, src_pte); + + /* + * We don't have to worry about the ordering of src and dst ptlocks + * because exclusive mmap_sem (or the i_mmap_lock) prevents deadlock. + */ + if (src_ptl != dst_ptl) + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + + pte = huge_ptep_get_and_clear(mm, old_addr, src_pte); + set_huge_pte_at(mm, new_addr, dst_pte, pte); + + if (src_ptl != dst_ptl) + spin_unlock(src_ptl); + spin_unlock(dst_ptl); +} + +int move_hugetlb_page_tables(struct vm_area_struct *vma, + struct vm_area_struct *new_vma, + unsigned long old_addr, unsigned long new_addr, + unsigned long len) +{ + struct hstate *h = hstate_vma(vma); + struct address_space *mapping = vma->vm_file->f_mapping; + unsigned long sz = huge_page_size(h); + struct mm_struct *mm = vma->vm_mm; + unsigned long old_end = old_addr + len; + unsigned long last_addr_mask; + pte_t *src_pte, *dst_pte; + struct mmu_notifier_range range; + bool shared_pmd = false; + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, old_addr, + old_end); + adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); + /* + * In case of shared PMDs, we should cover the maximum possible + * range. + */ + flush_cache_range(vma, range.start, range.end); + + mmu_notifier_invalidate_range_start(&range); + last_addr_mask = hugetlb_mask_last_page(h); + /* Prevent race with file truncation */ + hugetlb_vma_lock_write(vma); + i_mmap_lock_write(mapping); + for (; old_addr < old_end; old_addr += sz, new_addr += sz) { + src_pte = huge_pte_offset(mm, old_addr, sz); + if (!src_pte) { + old_addr |= last_addr_mask; + new_addr |= last_addr_mask; + continue; + } + if (huge_pte_none(huge_ptep_get(src_pte))) + continue; + + if (huge_pmd_unshare(mm, vma, old_addr, src_pte)) { + shared_pmd = true; + old_addr |= last_addr_mask; + new_addr |= last_addr_mask; + continue; + } + + dst_pte = huge_pte_alloc(mm, new_vma, new_addr, sz); + if (!dst_pte) + break; + + move_huge_pte(vma, old_addr, new_addr, src_pte, dst_pte); + } + + if (shared_pmd) + flush_tlb_range(vma, range.start, range.end); + else + flush_tlb_range(vma, old_end - len, old_end); + mmu_notifier_invalidate_range_end(&range); + i_mmap_unlock_write(mapping); + hugetlb_vma_unlock_write(vma); + + return len + old_addr - old_end; +} + +static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, + unsigned long start, unsigned long end, + struct page *ref_page, zap_flags_t zap_flags) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long address; + pte_t *ptep; + pte_t pte; + spinlock_t *ptl; + struct page *page; + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + struct mmu_notifier_range range; + unsigned long last_addr_mask; + bool force_flush = false; + + WARN_ON(!is_vm_hugetlb_page(vma)); + BUG_ON(start & ~huge_page_mask(h)); + BUG_ON(end & ~huge_page_mask(h)); + + /* + * This is a hugetlb vma, all the pte entries should point + * to huge page. + */ + tlb_change_page_size(tlb, sz); + tlb_start_vma(tlb, vma); + + /* + * If sharing possible, alert mmu notifiers of worst case. + */ + mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, mm, start, + end); + adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); + mmu_notifier_invalidate_range_start(&range); + last_addr_mask = hugetlb_mask_last_page(h); + address = start; + for (; address < end; address += sz) { + ptep = huge_pte_offset(mm, address, sz); + if (!ptep) { + address |= last_addr_mask; + continue; + } + + ptl = huge_pte_lock(h, mm, ptep); + if (huge_pmd_unshare(mm, vma, address, ptep)) { + spin_unlock(ptl); + tlb_flush_pmd_range(tlb, address & PUD_MASK, PUD_SIZE); + force_flush = true; + address |= last_addr_mask; + continue; + } + + pte = huge_ptep_get(ptep); + if (huge_pte_none(pte)) { + spin_unlock(ptl); + continue; + } + + /* + * Migrating hugepage or HWPoisoned hugepage is already + * unmapped and its refcount is dropped, so just clear pte here. + */ + if (unlikely(!pte_present(pte))) { +#ifdef CONFIG_PTE_MARKER_UFFD_WP + /* + * If the pte was wr-protected by uffd-wp in any of the + * swap forms, meanwhile the caller does not want to + * drop the uffd-wp bit in this zap, then replace the + * pte with a marker. + */ + if (pte_swp_uffd_wp_any(pte) && + !(zap_flags & ZAP_FLAG_DROP_MARKER)) + set_huge_pte_at(mm, address, ptep, + make_pte_marker(PTE_MARKER_UFFD_WP)); + else +#endif + huge_pte_clear(mm, address, ptep, sz); + spin_unlock(ptl); + continue; + } + + page = pte_page(pte); + /* + * If a reference page is supplied, it is because a specific + * page is being unmapped, not a range. Ensure the page we + * are about to unmap is the actual page of interest. + */ + if (ref_page) { + if (page != ref_page) { + spin_unlock(ptl); + continue; + } + /* + * Mark the VMA as having unmapped its page so that + * future faults in this VMA will fail rather than + * looking like data was lost + */ + set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); + } + + pte = huge_ptep_get_and_clear(mm, address, ptep); + tlb_remove_huge_tlb_entry(h, tlb, ptep, address); + if (huge_pte_dirty(pte)) + set_page_dirty(page); +#ifdef CONFIG_PTE_MARKER_UFFD_WP + /* Leave a uffd-wp pte marker if needed */ + if (huge_pte_uffd_wp(pte) && + !(zap_flags & ZAP_FLAG_DROP_MARKER)) + set_huge_pte_at(mm, address, ptep, + make_pte_marker(PTE_MARKER_UFFD_WP)); +#endif + hugetlb_count_sub(pages_per_huge_page(h), mm); + page_remove_rmap(page, vma, true); + + spin_unlock(ptl); + tlb_remove_page_size(tlb, page, huge_page_size(h)); + /* + * Bail out after unmapping reference page if supplied + */ + if (ref_page) + break; + } + mmu_notifier_invalidate_range_end(&range); + tlb_end_vma(tlb, vma); + + /* + * If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We + * could defer the flush until now, since by holding i_mmap_rwsem we + * guaranteed that the last refernece would not be dropped. But we must + * do the flushing before we return, as otherwise i_mmap_rwsem will be + * dropped and the last reference to the shared PMDs page might be + * dropped as well. + * + * In theory we could defer the freeing of the PMD pages as well, but + * huge_pmd_unshare() relies on the exact page_count for the PMD page to + * detect sharing, so we cannot defer the release of the page either. + * Instead, do flush now. + */ + if (force_flush) + tlb_flush_mmu_tlbonly(tlb); +} + +void __unmap_hugepage_range_final(struct mmu_gather *tlb, + struct vm_area_struct *vma, unsigned long start, + unsigned long end, struct page *ref_page, + zap_flags_t zap_flags) +{ + hugetlb_vma_lock_write(vma); + i_mmap_lock_write(vma->vm_file->f_mapping); + + __unmap_hugepage_range(tlb, vma, start, end, ref_page, zap_flags); + + if (zap_flags & ZAP_FLAG_UNMAP) { /* final unmap */ + /* + * Unlock and free the vma lock before releasing i_mmap_rwsem. + * When the vma_lock is freed, this makes the vma ineligible + * for pmd sharing. And, i_mmap_rwsem is required to set up + * pmd sharing. This is important as page tables for this + * unmapped range will be asynchrously deleted. If the page + * tables are shared, there will be issues when accessed by + * someone else. + */ + __hugetlb_vma_unlock_write_free(vma); + i_mmap_unlock_write(vma->vm_file->f_mapping); + } else { + i_mmap_unlock_write(vma->vm_file->f_mapping); + hugetlb_vma_unlock_write(vma); + } +} + +void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, + unsigned long end, struct page *ref_page, + zap_flags_t zap_flags) +{ + struct mmu_gather tlb; + + tlb_gather_mmu(&tlb, vma->vm_mm); + __unmap_hugepage_range(&tlb, vma, start, end, ref_page, zap_flags); + tlb_finish_mmu(&tlb); +} + +/* + * This is called when the original mapper is failing to COW a MAP_PRIVATE + * mapping it owns the reserve page for. The intention is to unmap the page + * from other VMAs and let the children be SIGKILLed if they are faulting the + * same region. + */ +static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, + struct page *page, unsigned long address) +{ + struct hstate *h = hstate_vma(vma); + struct vm_area_struct *iter_vma; + struct address_space *mapping; + pgoff_t pgoff; + + /* + * vm_pgoff is in PAGE_SIZE units, hence the different calculation + * from page cache lookup which is in HPAGE_SIZE units. + */ + address = address & huge_page_mask(h); + pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + + vma->vm_pgoff; + mapping = vma->vm_file->f_mapping; + + /* + * Take the mapping lock for the duration of the table walk. As + * this mapping should be shared between all the VMAs, + * __unmap_hugepage_range() is called as the lock is already held + */ + i_mmap_lock_write(mapping); + vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) { + /* Do not unmap the current VMA */ + if (iter_vma == vma) + continue; + + /* + * Shared VMAs have their own reserves and do not affect + * MAP_PRIVATE accounting but it is possible that a shared + * VMA is using the same page so check and skip such VMAs. + */ + if (iter_vma->vm_flags & VM_MAYSHARE) + continue; + + /* + * Unmap the page from other VMAs without their own reserves. + * They get marked to be SIGKILLed if they fault in these + * areas. This is because a future no-page fault on this VMA + * could insert a zeroed page instead of the data existing + * from the time of fork. This would look like data corruption + */ + if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) + unmap_hugepage_range(iter_vma, address, + address + huge_page_size(h), page, 0); + } + i_mmap_unlock_write(mapping); +} + +/* + * hugetlb_wp() should be called with page lock of the original hugepage held. + * Called with hugetlb_fault_mutex_table held and pte_page locked so we + * cannot race with other handlers or page migration. + * Keep the pte_same checks anyway to make transition from the mutex easier. + */ +static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, unsigned int flags, + struct page *pagecache_page, spinlock_t *ptl) +{ + const bool unshare = flags & FAULT_FLAG_UNSHARE; + pte_t pte = huge_ptep_get(ptep); + struct hstate *h = hstate_vma(vma); + struct page *old_page, *new_page; + int outside_reserve = 0; + vm_fault_t ret = 0; + unsigned long haddr = address & huge_page_mask(h); + struct mmu_notifier_range range; + + VM_BUG_ON(unshare && (flags & FOLL_WRITE)); + VM_BUG_ON(!unshare && !(flags & FOLL_WRITE)); + + /* + * Never handle CoW for uffd-wp protected pages. It should be only + * handled when the uffd-wp protection is removed. + * + * Note that only the CoW optimization path (in hugetlb_no_page()) + * can trigger this, because hugetlb_fault() will always resolve + * uffd-wp bit first. + */ + if (!unshare && huge_pte_uffd_wp(pte)) + return 0; + + /* + * hugetlb does not support FOLL_FORCE-style write faults that keep the + * PTE mapped R/O such as maybe_mkwrite() would do. + */ + if (WARN_ON_ONCE(!unshare && !(vma->vm_flags & VM_WRITE))) + return VM_FAULT_SIGSEGV; + + /* Let's take out MAP_SHARED mappings first. */ + if (vma->vm_flags & VM_MAYSHARE) { + if (unlikely(unshare)) + return 0; + set_huge_ptep_writable(vma, haddr, ptep); + return 0; + } + + old_page = pte_page(pte); + + delayacct_wpcopy_start(); + +retry_avoidcopy: + /* + * If no-one else is actually using this page, we're the exclusive + * owner and can reuse this page. + */ + if (page_mapcount(old_page) == 1 && PageAnon(old_page)) { + if (!PageAnonExclusive(old_page)) + page_move_anon_rmap(old_page, vma); + if (likely(!unshare)) + set_huge_ptep_writable(vma, haddr, ptep); + + delayacct_wpcopy_end(); + return 0; + } + VM_BUG_ON_PAGE(PageAnon(old_page) && PageAnonExclusive(old_page), + old_page); + + /* + * If the process that created a MAP_PRIVATE mapping is about to + * perform a COW due to a shared page count, attempt to satisfy + * the allocation without using the existing reserves. The pagecache + * page is used to determine if the reserve at this address was + * consumed or not. If reserves were used, a partial faulted mapping + * at the time of fork() could consume its reserves on COW instead + * of the full address range. + */ + if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && + old_page != pagecache_page) + outside_reserve = 1; + + get_page(old_page); + + /* + * Drop page table lock as buddy allocator may be called. It will + * be acquired again before returning to the caller, as expected. + */ + spin_unlock(ptl); + new_page = alloc_huge_page(vma, haddr, outside_reserve); + + if (IS_ERR(new_page)) { + /* + * If a process owning a MAP_PRIVATE mapping fails to COW, + * it is due to references held by a child and an insufficient + * huge page pool. To guarantee the original mappers + * reliability, unmap the page from child processes. The child + * may get SIGKILLed if it later faults. + */ + if (outside_reserve) { + struct address_space *mapping = vma->vm_file->f_mapping; + pgoff_t idx; + u32 hash; + + put_page(old_page); + /* + * Drop hugetlb_fault_mutex and vma_lock before + * unmapping. unmapping needs to hold vma_lock + * in write mode. Dropping vma_lock in read mode + * here is OK as COW mappings do not interact with + * PMD sharing. + * + * Reacquire both after unmap operation. + */ + idx = vma_hugecache_offset(h, vma, haddr); + hash = hugetlb_fault_mutex_hash(mapping, idx); + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + + unmap_ref_private(mm, vma, old_page, haddr); + + mutex_lock(&hugetlb_fault_mutex_table[hash]); + hugetlb_vma_lock_read(vma); + spin_lock(ptl); + ptep = huge_pte_offset(mm, haddr, huge_page_size(h)); + if (likely(ptep && + pte_same(huge_ptep_get(ptep), pte))) + goto retry_avoidcopy; + /* + * race occurs while re-acquiring page table + * lock, and our job is done. + */ + delayacct_wpcopy_end(); + return 0; + } + + ret = vmf_error(PTR_ERR(new_page)); + goto out_release_old; + } + + /* + * When the original hugepage is shared one, it does not have + * anon_vma prepared. + */ + if (unlikely(anon_vma_prepare(vma))) { + ret = VM_FAULT_OOM; + goto out_release_all; + } + + copy_user_huge_page(new_page, old_page, address, vma, + pages_per_huge_page(h)); + __SetPageUptodate(new_page); + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, haddr, + haddr + huge_page_size(h)); + mmu_notifier_invalidate_range_start(&range); + + /* + * Retake the page table lock to check for racing updates + * before the page tables are altered + */ + spin_lock(ptl); + ptep = huge_pte_offset(mm, haddr, huge_page_size(h)); + if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) { + ClearHPageRestoreReserve(new_page); + + /* Break COW or unshare */ + huge_ptep_clear_flush(vma, haddr, ptep); + mmu_notifier_invalidate_range(mm, range.start, range.end); + page_remove_rmap(old_page, vma, true); + hugepage_add_new_anon_rmap(new_page, vma, haddr); + set_huge_pte_at(mm, haddr, ptep, + make_huge_pte(vma, new_page, !unshare)); + SetHPageMigratable(new_page); + /* Make the old page be freed below */ + new_page = old_page; + } + spin_unlock(ptl); + mmu_notifier_invalidate_range_end(&range); +out_release_all: + /* + * No restore in case of successful pagetable update (Break COW or + * unshare) + */ + if (new_page != old_page) + restore_reserve_on_error(h, vma, haddr, new_page); + put_page(new_page); +out_release_old: + put_page(old_page); + + spin_lock(ptl); /* Caller expects lock to be held */ + + delayacct_wpcopy_end(); + return ret; +} + +/* + * Return whether there is a pagecache page to back given address within VMA. + * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. + */ +static bool hugetlbfs_pagecache_present(struct hstate *h, + struct vm_area_struct *vma, unsigned long address) +{ + struct address_space *mapping; + pgoff_t idx; + struct page *page; + + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, address); + + page = find_get_page(mapping, idx); + if (page) + put_page(page); + return page != NULL; +} + +int hugetlb_add_to_page_cache(struct page *page, struct address_space *mapping, + pgoff_t idx) +{ + struct folio *folio = page_folio(page); + struct inode *inode = mapping->host; + struct hstate *h = hstate_inode(inode); + int err; + + __folio_set_locked(folio); + err = __filemap_add_folio(mapping, folio, idx, GFP_KERNEL, NULL); + + if (unlikely(err)) { + __folio_clear_locked(folio); + return err; + } + ClearHPageRestoreReserve(page); + + /* + * mark folio dirty so that it will not be removed from cache/file + * by non-hugetlbfs specific code paths. + */ + folio_mark_dirty(folio); + + spin_lock(&inode->i_lock); + inode->i_blocks += blocks_per_huge_page(h); + spin_unlock(&inode->i_lock); + return 0; +} + +static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma, + struct address_space *mapping, + pgoff_t idx, + unsigned int flags, + unsigned long haddr, + unsigned long addr, + unsigned long reason) +{ + u32 hash; + struct vm_fault vmf = { + .vma = vma, + .address = haddr, + .real_address = addr, + .flags = flags, + + /* + * Hard to debug if it ends up being + * used by a callee that assumes + * something about the other + * uninitialized fields... same as in + * memory.c + */ + }; + + /* + * vma_lock and hugetlb_fault_mutex must be dropped before handling + * userfault. Also mmap_lock could be dropped due to handling + * userfault, any vma operation should be careful from here. + */ + hugetlb_vma_unlock_read(vma); + hash = hugetlb_fault_mutex_hash(mapping, idx); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + return handle_userfault(&vmf, reason); +} + +/* + * Recheck pte with pgtable lock. Returns true if pte didn't change, or + * false if pte changed or is changing. + */ +static bool hugetlb_pte_stable(struct hstate *h, struct mm_struct *mm, + pte_t *ptep, pte_t old_pte) +{ + spinlock_t *ptl; + bool same; + + ptl = huge_pte_lock(h, mm, ptep); + same = pte_same(huge_ptep_get(ptep), old_pte); + spin_unlock(ptl); + + return same; +} + +static vm_fault_t hugetlb_no_page(struct mm_struct *mm, + struct vm_area_struct *vma, + struct address_space *mapping, pgoff_t idx, + unsigned long address, pte_t *ptep, + pte_t old_pte, unsigned int flags) +{ + struct hstate *h = hstate_vma(vma); + vm_fault_t ret = VM_FAULT_SIGBUS; + int anon_rmap = 0; + unsigned long size; + struct page *page; + pte_t new_pte; + spinlock_t *ptl; + unsigned long haddr = address & huge_page_mask(h); + bool new_page, new_pagecache_page = false; + u32 hash = hugetlb_fault_mutex_hash(mapping, idx); + + /* + * Currently, we are forced to kill the process in the event the + * original mapper has unmapped pages from the child due to a failed + * COW/unsharing. Warn that such a situation has occurred as it may not + * be obvious. + */ + if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { + pr_warn_ratelimited("PID %d killed due to inadequate hugepage pool\n", + current->pid); + goto out; + } + + /* + * Use page lock to guard against racing truncation + * before we get page_table_lock. + */ + new_page = false; + page = find_lock_page(mapping, idx); + if (!page) { + size = i_size_read(mapping->host) >> huge_page_shift(h); + if (idx >= size) + goto out; + /* Check for page in userfault range */ + if (userfaultfd_missing(vma)) { + /* + * Since hugetlb_no_page() was examining pte + * without pgtable lock, we need to re-test under + * lock because the pte may not be stable and could + * have changed from under us. Try to detect + * either changed or during-changing ptes and retry + * properly when needed. + * + * Note that userfaultfd is actually fine with + * false positives (e.g. caused by pte changed), + * but not wrong logical events (e.g. caused by + * reading a pte during changing). The latter can + * confuse the userspace, so the strictness is very + * much preferred. E.g., MISSING event should + * never happen on the page after UFFDIO_COPY has + * correctly installed the page and returned. + */ + if (!hugetlb_pte_stable(h, mm, ptep, old_pte)) { + ret = 0; + goto out; + } + + return hugetlb_handle_userfault(vma, mapping, idx, flags, + haddr, address, + VM_UFFD_MISSING); + } + + page = alloc_huge_page(vma, haddr, 0); + if (IS_ERR(page)) { + /* + * Returning error will result in faulting task being + * sent SIGBUS. The hugetlb fault mutex prevents two + * tasks from racing to fault in the same page which + * could result in false unable to allocate errors. + * Page migration does not take the fault mutex, but + * does a clear then write of pte's under page table + * lock. Page fault code could race with migration, + * notice the clear pte and try to allocate a page + * here. Before returning error, get ptl and make + * sure there really is no pte entry. + */ + if (hugetlb_pte_stable(h, mm, ptep, old_pte)) + ret = vmf_error(PTR_ERR(page)); + else + ret = 0; + goto out; + } + clear_huge_page(page, address, pages_per_huge_page(h)); + __SetPageUptodate(page); + new_page = true; + + if (vma->vm_flags & VM_MAYSHARE) { + int err = hugetlb_add_to_page_cache(page, mapping, idx); + if (err) { + /* + * err can't be -EEXIST which implies someone + * else consumed the reservation since hugetlb + * fault mutex is held when add a hugetlb page + * to the page cache. So it's safe to call + * restore_reserve_on_error() here. + */ + restore_reserve_on_error(h, vma, haddr, page); + put_page(page); + goto out; + } + new_pagecache_page = true; + } else { + lock_page(page); + if (unlikely(anon_vma_prepare(vma))) { + ret = VM_FAULT_OOM; + goto backout_unlocked; + } + anon_rmap = 1; + } + } else { + /* + * If memory error occurs between mmap() and fault, some process + * don't have hwpoisoned swap entry for errored virtual address. + * So we need to block hugepage fault by PG_hwpoison bit check. + */ + if (unlikely(PageHWPoison(page))) { + ret = VM_FAULT_HWPOISON_LARGE | + VM_FAULT_SET_HINDEX(hstate_index(h)); + goto backout_unlocked; + } + + /* Check for page in userfault range. */ + if (userfaultfd_minor(vma)) { + unlock_page(page); + put_page(page); + /* See comment in userfaultfd_missing() block above */ + if (!hugetlb_pte_stable(h, mm, ptep, old_pte)) { + ret = 0; + goto out; + } + return hugetlb_handle_userfault(vma, mapping, idx, flags, + haddr, address, + VM_UFFD_MINOR); + } + } + + /* + * If we are going to COW a private mapping later, we examine the + * pending reservations for this page now. This will ensure that + * any allocations necessary to record that reservation occur outside + * the spinlock. + */ + if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { + if (vma_needs_reservation(h, vma, haddr) < 0) { + ret = VM_FAULT_OOM; + goto backout_unlocked; + } + /* Just decrements count, does not deallocate */ + vma_end_reservation(h, vma, haddr); + } + + ptl = huge_pte_lock(h, mm, ptep); + ret = 0; + /* If pte changed from under us, retry */ + if (!pte_same(huge_ptep_get(ptep), old_pte)) + goto backout; + + if (anon_rmap) { + ClearHPageRestoreReserve(page); + hugepage_add_new_anon_rmap(page, vma, haddr); + } else + page_dup_file_rmap(page, true); + new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) + && (vma->vm_flags & VM_SHARED))); + /* + * If this pte was previously wr-protected, keep it wr-protected even + * if populated. + */ + if (unlikely(pte_marker_uffd_wp(old_pte))) + new_pte = huge_pte_wrprotect(huge_pte_mkuffd_wp(new_pte)); + set_huge_pte_at(mm, haddr, ptep, new_pte); + + hugetlb_count_add(pages_per_huge_page(h), mm); + if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { + /* Optimization, do the COW without a second fault */ + ret = hugetlb_wp(mm, vma, address, ptep, flags, page, ptl); + } + + spin_unlock(ptl); + + /* + * Only set HPageMigratable in newly allocated pages. Existing pages + * found in the pagecache may not have HPageMigratableset if they have + * been isolated for migration. + */ + if (new_page) + SetHPageMigratable(page); + + unlock_page(page); +out: + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + return ret; + +backout: + spin_unlock(ptl); +backout_unlocked: + if (new_page && !new_pagecache_page) + restore_reserve_on_error(h, vma, haddr, page); + + unlock_page(page); + put_page(page); + goto out; +} + +#ifdef CONFIG_SMP +u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx) +{ + unsigned long key[2]; + u32 hash; + + key[0] = (unsigned long) mapping; + key[1] = idx; + + hash = jhash2((u32 *)&key, sizeof(key)/(sizeof(u32)), 0); + + return hash & (num_fault_mutexes - 1); +} +#else +/* + * For uniprocessor systems we always use a single mutex, so just + * return 0 and avoid the hashing overhead. + */ +u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx) +{ + return 0; +} +#endif + +vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long address, unsigned int flags) +{ + pte_t *ptep, entry; + spinlock_t *ptl; + vm_fault_t ret; + u32 hash; + pgoff_t idx; + struct page *page = NULL; + struct page *pagecache_page = NULL; + struct hstate *h = hstate_vma(vma); + struct address_space *mapping; + int need_wait_lock = 0; + unsigned long haddr = address & huge_page_mask(h); + + ptep = huge_pte_offset(mm, haddr, huge_page_size(h)); + if (ptep) { + /* + * Since we hold no locks, ptep could be stale. That is + * OK as we are only making decisions based on content and + * not actually modifying content here. + */ + entry = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_migration(entry))) { + migration_entry_wait_huge(vma, ptep); + return 0; + } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) + return VM_FAULT_HWPOISON_LARGE | + VM_FAULT_SET_HINDEX(hstate_index(h)); + } + + /* + * Serialize hugepage allocation and instantiation, so that we don't + * get spurious allocation failures if two CPUs race to instantiate + * the same page in the page cache. + */ + mapping = vma->vm_file->f_mapping; + idx = vma_hugecache_offset(h, vma, haddr); + hash = hugetlb_fault_mutex_hash(mapping, idx); + mutex_lock(&hugetlb_fault_mutex_table[hash]); + + /* + * Acquire vma lock before calling huge_pte_alloc and hold + * until finished with ptep. This prevents huge_pmd_unshare from + * being called elsewhere and making the ptep no longer valid. + * + * ptep could have already be assigned via huge_pte_offset. That + * is OK, as huge_pte_alloc will return the same value unless + * something has changed. + */ + hugetlb_vma_lock_read(vma); + ptep = huge_pte_alloc(mm, vma, haddr, huge_page_size(h)); + if (!ptep) { + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + return VM_FAULT_OOM; + } + + entry = huge_ptep_get(ptep); + /* PTE markers should be handled the same way as none pte */ + if (huge_pte_none_mostly(entry)) + /* + * hugetlb_no_page will drop vma lock and hugetlb fault + * mutex internally, which make us return immediately. + */ + return hugetlb_no_page(mm, vma, mapping, idx, address, ptep, + entry, flags); + + ret = 0; + + /* + * entry could be a migration/hwpoison entry at this point, so this + * check prevents the kernel from going below assuming that we have + * an active hugepage in pagecache. This goto expects the 2nd page + * fault, and is_hugetlb_entry_(migration|hwpoisoned) check will + * properly handle it. + */ + if (!pte_present(entry)) + goto out_mutex; + + /* + * If we are going to COW/unshare the mapping later, we examine the + * pending reservations for this page now. This will ensure that any + * allocations necessary to record that reservation occur outside the + * spinlock. Also lookup the pagecache page now as it is used to + * determine if a reservation has been consumed. + */ + if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) && + !(vma->vm_flags & VM_MAYSHARE) && !huge_pte_write(entry)) { + if (vma_needs_reservation(h, vma, haddr) < 0) { + ret = VM_FAULT_OOM; + goto out_mutex; + } + /* Just decrements count, does not deallocate */ + vma_end_reservation(h, vma, haddr); + + pagecache_page = find_lock_page(mapping, idx); + } + + ptl = huge_pte_lock(h, mm, ptep); + + /* Check for a racing update before calling hugetlb_wp() */ + if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) + goto out_ptl; + + /* Handle userfault-wp first, before trying to lock more pages */ + if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(ptep)) && + (flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { + struct vm_fault vmf = { + .vma = vma, + .address = haddr, + .real_address = address, + .flags = flags, + }; + + spin_unlock(ptl); + if (pagecache_page) { + unlock_page(pagecache_page); + put_page(pagecache_page); + } + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + return handle_userfault(&vmf, VM_UFFD_WP); + } + + /* + * hugetlb_wp() requires page locks of pte_page(entry) and + * pagecache_page, so here we need take the former one + * when page != pagecache_page or !pagecache_page. + */ + page = pte_page(entry); + if (page != pagecache_page) + if (!trylock_page(page)) { + need_wait_lock = 1; + goto out_ptl; + } + + get_page(page); + + if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { + if (!huge_pte_write(entry)) { + ret = hugetlb_wp(mm, vma, address, ptep, flags, + pagecache_page, ptl); + goto out_put_page; + } else if (likely(flags & FAULT_FLAG_WRITE)) { + entry = huge_pte_mkdirty(entry); + } + } + entry = pte_mkyoung(entry); + if (huge_ptep_set_access_flags(vma, haddr, ptep, entry, + flags & FAULT_FLAG_WRITE)) + update_mmu_cache(vma, haddr, ptep); +out_put_page: + if (page != pagecache_page) + unlock_page(page); + put_page(page); +out_ptl: + spin_unlock(ptl); + + if (pagecache_page) { + unlock_page(pagecache_page); + put_page(pagecache_page); + } +out_mutex: + hugetlb_vma_unlock_read(vma); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); + /* + * Generally it's safe to hold refcount during waiting page lock. But + * here we just wait to defer the next page fault to avoid busy loop and + * the page is not used after unlocked before returning from the current + * page fault. So we are safe from accessing freed page, even if we wait + * here without taking refcount. + */ + if (need_wait_lock) + wait_on_page_locked(page); + return ret; +} + +#ifdef CONFIG_USERFAULTFD +/* + * Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with + * modifications for huge pages. + */ +int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, + pte_t *dst_pte, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, + unsigned long src_addr, + enum mcopy_atomic_mode mode, + struct page **pagep, + bool wp_copy) +{ + bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); + struct hstate *h = hstate_vma(dst_vma); + struct address_space *mapping = dst_vma->vm_file->f_mapping; + pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr); + unsigned long size; + int vm_shared = dst_vma->vm_flags & VM_SHARED; + pte_t _dst_pte; + spinlock_t *ptl; + int ret = -ENOMEM; + struct page *page; + int writable; + bool page_in_pagecache = false; + + if (is_continue) { + ret = -EFAULT; + page = find_lock_page(mapping, idx); + if (!page) + goto out; + page_in_pagecache = true; + } else if (!*pagep) { + /* If a page already exists, then it's UFFDIO_COPY for + * a non-missing case. Return -EEXIST. + */ + if (vm_shared && + hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { + ret = -EEXIST; + goto out; + } + + page = alloc_huge_page(dst_vma, dst_addr, 0); + if (IS_ERR(page)) { + ret = -ENOMEM; + goto out; + } + + ret = copy_huge_page_from_user(page, + (const void __user *) src_addr, + pages_per_huge_page(h), false); + + /* fallback to copy_from_user outside mmap_lock */ + if (unlikely(ret)) { + ret = -ENOENT; + /* Free the allocated page which may have + * consumed a reservation. + */ + restore_reserve_on_error(h, dst_vma, dst_addr, page); + put_page(page); + + /* Allocate a temporary page to hold the copied + * contents. + */ + page = alloc_huge_page_vma(h, dst_vma, dst_addr); + if (!page) { + ret = -ENOMEM; + goto out; + } + *pagep = page; + /* Set the outparam pagep and return to the caller to + * copy the contents outside the lock. Don't free the + * page. + */ + goto out; + } + } else { + if (vm_shared && + hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { + put_page(*pagep); + ret = -EEXIST; + *pagep = NULL; + goto out; + } + + page = alloc_huge_page(dst_vma, dst_addr, 0); + if (IS_ERR(page)) { + put_page(*pagep); + ret = -ENOMEM; + *pagep = NULL; + goto out; + } + copy_user_huge_page(page, *pagep, dst_addr, dst_vma, + pages_per_huge_page(h)); + put_page(*pagep); + *pagep = NULL; + } + + /* + * The memory barrier inside __SetPageUptodate makes sure that + * preceding stores to the page contents become visible before + * the set_pte_at() write. + */ + __SetPageUptodate(page); + + /* Add shared, newly allocated pages to the page cache. */ + if (vm_shared && !is_continue) { + size = i_size_read(mapping->host) >> huge_page_shift(h); + ret = -EFAULT; + if (idx >= size) + goto out_release_nounlock; + + /* + * Serialization between remove_inode_hugepages() and + * hugetlb_add_to_page_cache() below happens through the + * hugetlb_fault_mutex_table that here must be hold by + * the caller. + */ + ret = hugetlb_add_to_page_cache(page, mapping, idx); + if (ret) + goto out_release_nounlock; + page_in_pagecache = true; + } + + ptl = huge_pte_lock(h, dst_mm, dst_pte); + + ret = -EIO; + if (PageHWPoison(page)) + goto out_release_unlock; + + /* + * We allow to overwrite a pte marker: consider when both MISSING|WP + * registered, we firstly wr-protect a none pte which has no page cache + * page backing it, then access the page. + */ + ret = -EEXIST; + if (!huge_pte_none_mostly(huge_ptep_get(dst_pte))) + goto out_release_unlock; + + if (page_in_pagecache) { + page_dup_file_rmap(page, true); + } else { + ClearHPageRestoreReserve(page); + hugepage_add_new_anon_rmap(page, dst_vma, dst_addr); + } + + /* + * For either: (1) CONTINUE on a non-shared VMA, or (2) UFFDIO_COPY + * with wp flag set, don't set pte write bit. + */ + if (wp_copy || (is_continue && !vm_shared)) + writable = 0; + else + writable = dst_vma->vm_flags & VM_WRITE; + + _dst_pte = make_huge_pte(dst_vma, page, writable); + /* + * Always mark UFFDIO_COPY page dirty; note that this may not be + * extremely important for hugetlbfs for now since swapping is not + * supported, but we should still be clear in that this page cannot be + * thrown away at will, even if write bit not set. + */ + _dst_pte = huge_pte_mkdirty(_dst_pte); + _dst_pte = pte_mkyoung(_dst_pte); + + if (wp_copy) + _dst_pte = huge_pte_mkuffd_wp(_dst_pte); + + set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + + hugetlb_count_add(pages_per_huge_page(h), dst_mm); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(dst_vma, dst_addr, dst_pte); + + spin_unlock(ptl); + if (!is_continue) + SetHPageMigratable(page); + if (vm_shared || is_continue) + unlock_page(page); + ret = 0; +out: + return ret; +out_release_unlock: + spin_unlock(ptl); + if (vm_shared || is_continue) + unlock_page(page); +out_release_nounlock: + if (!page_in_pagecache) + restore_reserve_on_error(h, dst_vma, dst_addr, page); + put_page(page); + goto out; +} +#endif /* CONFIG_USERFAULTFD */ + +static void record_subpages_vmas(struct page *page, struct vm_area_struct *vma, + int refs, struct page **pages, + struct vm_area_struct **vmas) +{ + int nr; + + for (nr = 0; nr < refs; nr++) { + if (likely(pages)) + pages[nr] = nth_page(page, nr); + if (vmas) + vmas[nr] = vma; + } +} + +static inline bool __follow_hugetlb_must_fault(unsigned int flags, pte_t *pte, + bool *unshare) +{ + pte_t pteval = huge_ptep_get(pte); + + *unshare = false; + if (is_swap_pte(pteval)) + return true; + if (huge_pte_write(pteval)) + return false; + if (flags & FOLL_WRITE) + return true; + if (gup_must_unshare(flags, pte_page(pteval))) { + *unshare = true; + return true; + } + return false; +} + +long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, + struct page **pages, struct vm_area_struct **vmas, + unsigned long *position, unsigned long *nr_pages, + long i, unsigned int flags, int *locked) +{ + unsigned long pfn_offset; + unsigned long vaddr = *position; + unsigned long remainder = *nr_pages; + struct hstate *h = hstate_vma(vma); + int err = -EFAULT, refs; + + while (vaddr < vma->vm_end && remainder) { + pte_t *pte; + spinlock_t *ptl = NULL; + bool unshare = false; + int absent; + struct page *page; + + /* + * If we have a pending SIGKILL, don't keep faulting pages and + * potentially allocating memory. + */ + if (fatal_signal_pending(current)) { + remainder = 0; + break; + } + + /* + * Some archs (sparc64, sh*) have multiple pte_ts to + * each hugepage. We have to make sure we get the + * first, for the page indexing below to work. + * + * Note that page table lock is not held when pte is null. + */ + pte = huge_pte_offset(mm, vaddr & huge_page_mask(h), + huge_page_size(h)); + if (pte) + ptl = huge_pte_lock(h, mm, pte); + absent = !pte || huge_pte_none(huge_ptep_get(pte)); + + /* + * When coredumping, it suits get_dump_page if we just return + * an error where there's an empty slot with no huge pagecache + * to back it. This way, we avoid allocating a hugepage, and + * the sparse dumpfile avoids allocating disk blocks, but its + * huge holes still show up with zeroes where they need to be. + */ + if (absent && (flags & FOLL_DUMP) && + !hugetlbfs_pagecache_present(h, vma, vaddr)) { + if (pte) + spin_unlock(ptl); + remainder = 0; + break; + } + + /* + * We need call hugetlb_fault for both hugepages under migration + * (in which case hugetlb_fault waits for the migration,) and + * hwpoisoned hugepages (in which case we need to prevent the + * caller from accessing to them.) In order to do this, we use + * here is_swap_pte instead of is_hugetlb_entry_migration and + * is_hugetlb_entry_hwpoisoned. This is because it simply covers + * both cases, and because we can't follow correct pages + * directly from any kind of swap entries. + */ + if (absent || + __follow_hugetlb_must_fault(flags, pte, &unshare)) { + vm_fault_t ret; + unsigned int fault_flags = 0; + + if (pte) + spin_unlock(ptl); + if (flags & FOLL_WRITE) + fault_flags |= FAULT_FLAG_WRITE; + else if (unshare) + fault_flags |= FAULT_FLAG_UNSHARE; + if (locked) + fault_flags |= FAULT_FLAG_ALLOW_RETRY | + FAULT_FLAG_KILLABLE; + if (flags & FOLL_NOWAIT) + fault_flags |= FAULT_FLAG_ALLOW_RETRY | + FAULT_FLAG_RETRY_NOWAIT; + if (flags & FOLL_TRIED) { + /* + * Note: FAULT_FLAG_ALLOW_RETRY and + * FAULT_FLAG_TRIED can co-exist + */ + fault_flags |= FAULT_FLAG_TRIED; + } + ret = hugetlb_fault(mm, vma, vaddr, fault_flags); + if (ret & VM_FAULT_ERROR) { + err = vm_fault_to_errno(ret, flags); + remainder = 0; + break; + } + if (ret & VM_FAULT_RETRY) { + if (locked && + !(fault_flags & FAULT_FLAG_RETRY_NOWAIT)) + *locked = 0; + *nr_pages = 0; + /* + * VM_FAULT_RETRY must not return an + * error, it will return zero + * instead. + * + * No need to update "position" as the + * caller will not check it after + * *nr_pages is set to 0. + */ + return i; + } + continue; + } + + pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; + page = pte_page(huge_ptep_get(pte)); + + VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && + !PageAnonExclusive(page), page); + + /* + * If subpage information not requested, update counters + * and skip the same_page loop below. + */ + if (!pages && !vmas && !pfn_offset && + (vaddr + huge_page_size(h) < vma->vm_end) && + (remainder >= pages_per_huge_page(h))) { + vaddr += huge_page_size(h); + remainder -= pages_per_huge_page(h); + i += pages_per_huge_page(h); + spin_unlock(ptl); + continue; + } + + /* vaddr may not be aligned to PAGE_SIZE */ + refs = min3(pages_per_huge_page(h) - pfn_offset, remainder, + (vma->vm_end - ALIGN_DOWN(vaddr, PAGE_SIZE)) >> PAGE_SHIFT); + + if (pages || vmas) + record_subpages_vmas(nth_page(page, pfn_offset), + vma, refs, + likely(pages) ? pages + i : NULL, + vmas ? vmas + i : NULL); + + if (pages) { + /* + * try_grab_folio() should always succeed here, + * because: a) we hold the ptl lock, and b) we've just + * checked that the huge page is present in the page + * tables. If the huge page is present, then the tail + * pages must also be present. The ptl prevents the + * head page and tail pages from being rearranged in + * any way. So this page must be available at this + * point, unless the page refcount overflowed: + */ + if (WARN_ON_ONCE(!try_grab_folio(pages[i], refs, + flags))) { + spin_unlock(ptl); + remainder = 0; + err = -ENOMEM; + break; + } + } + + vaddr += (refs << PAGE_SHIFT); + remainder -= refs; + i += refs; + + spin_unlock(ptl); + } + *nr_pages = remainder; + /* + * setting position is actually required only if remainder is + * not zero but it's faster not to add a "if (remainder)" + * branch. + */ + *position = vaddr; + + return i ? i : err; +} + +unsigned long hugetlb_change_protection(struct vm_area_struct *vma, + unsigned long address, unsigned long end, + pgprot_t newprot, unsigned long cp_flags) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long start = address; + pte_t *ptep; + pte_t pte; + struct hstate *h = hstate_vma(vma); + unsigned long pages = 0, psize = huge_page_size(h); + bool shared_pmd = false; + struct mmu_notifier_range range; + unsigned long last_addr_mask; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + + /* + * In the case of shared PMDs, the area to flush could be beyond + * start/end. Set range.start/range.end to cover the maximum possible + * range if PMD sharing is possible. + */ + mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, + 0, vma, mm, start, end); + adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); + + BUG_ON(address >= end); + flush_cache_range(vma, range.start, range.end); + + mmu_notifier_invalidate_range_start(&range); + hugetlb_vma_lock_write(vma); + i_mmap_lock_write(vma->vm_file->f_mapping); + last_addr_mask = hugetlb_mask_last_page(h); + for (; address < end; address += psize) { + spinlock_t *ptl; + ptep = huge_pte_offset(mm, address, psize); + if (!ptep) { + if (!uffd_wp) { + address |= last_addr_mask; + continue; + } + /* + * Userfaultfd wr-protect requires pgtable + * pre-allocations to install pte markers. + */ + ptep = huge_pte_alloc(mm, vma, address, psize); + if (!ptep) + break; + } + ptl = huge_pte_lock(h, mm, ptep); + if (huge_pmd_unshare(mm, vma, address, ptep)) { + /* + * When uffd-wp is enabled on the vma, unshare + * shouldn't happen at all. Warn about it if it + * happened due to some reason. + */ + WARN_ON_ONCE(uffd_wp || uffd_wp_resolve); + pages++; + spin_unlock(ptl); + shared_pmd = true; + address |= last_addr_mask; + continue; + } + pte = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) { + /* Nothing to do. */ + } else if (unlikely(is_hugetlb_entry_migration(pte))) { + swp_entry_t entry = pte_to_swp_entry(pte); + struct page *page = pfn_swap_entry_to_page(entry); + pte_t newpte = pte; + + if (is_writable_migration_entry(entry)) { + if (PageAnon(page)) + entry = make_readable_exclusive_migration_entry( + swp_offset(entry)); + else + entry = make_readable_migration_entry( + swp_offset(entry)); + newpte = swp_entry_to_pte(entry); + pages++; + } + + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); + if (!pte_same(pte, newpte)) + set_huge_pte_at(mm, address, ptep, newpte); + } else if (unlikely(is_pte_marker(pte))) { + /* No other markers apply for now. */ + WARN_ON_ONCE(!pte_marker_uffd_wp(pte)); + if (uffd_wp_resolve) + /* Safe to modify directly (non-present->none). */ + huge_pte_clear(mm, address, ptep, psize); + } else if (!huge_pte_none(pte)) { + pte_t old_pte; + unsigned int shift = huge_page_shift(hstate_vma(vma)); + + old_pte = huge_ptep_modify_prot_start(vma, address, ptep); + pte = huge_pte_modify(old_pte, newprot); + pte = arch_make_huge_pte(pte, shift, vma->vm_flags); + if (uffd_wp) + pte = huge_pte_mkuffd_wp(huge_pte_wrprotect(pte)); + else if (uffd_wp_resolve) + pte = huge_pte_clear_uffd_wp(pte); + huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte); + pages++; + } else { + /* None pte */ + if (unlikely(uffd_wp)) + /* Safe to modify directly (none->non-present). */ + set_huge_pte_at(mm, address, ptep, + make_pte_marker(PTE_MARKER_UFFD_WP)); + } + spin_unlock(ptl); + } + /* + * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare + * may have cleared our pud entry and done put_page on the page table: + * once we release i_mmap_rwsem, another task can do the final put_page + * and that page table be reused and filled with junk. If we actually + * did unshare a page of pmds, flush the range corresponding to the pud. + */ + if (shared_pmd) + flush_hugetlb_tlb_range(vma, range.start, range.end); + else + flush_hugetlb_tlb_range(vma, start, end); + /* + * No need to call mmu_notifier_invalidate_range() we are downgrading + * page table protection not changing it to point to a new page. + * + * See Documentation/mm/mmu_notifier.rst + */ + i_mmap_unlock_write(vma->vm_file->f_mapping); + hugetlb_vma_unlock_write(vma); + mmu_notifier_invalidate_range_end(&range); + + return pages << h->order; +} + +/* Return true if reservation was successful, false otherwise. */ +bool hugetlb_reserve_pages(struct inode *inode, + long from, long to, + struct vm_area_struct *vma, + vm_flags_t vm_flags) +{ + long chg, add = -1; + struct hstate *h = hstate_inode(inode); + struct hugepage_subpool *spool = subpool_inode(inode); + struct resv_map *resv_map; + struct hugetlb_cgroup *h_cg = NULL; + long gbl_reserve, regions_needed = 0; + + /* This should never happen */ + if (from > to) { + VM_WARN(1, "%s called with a negative range\n", __func__); + return false; + } + + /* + * vma specific semaphore used for pmd sharing and fault/truncation + * synchronization + */ + hugetlb_vma_lock_alloc(vma); + + /* + * Only apply hugepage reservation if asked. At fault time, an + * attempt will be made for VM_NORESERVE to allocate a page + * without using reserves + */ + if (vm_flags & VM_NORESERVE) + return true; + + /* + * Shared mappings base their reservation on the number of pages that + * are already allocated on behalf of the file. Private mappings need + * to reserve the full area even if read-only as mprotect() may be + * called to make the mapping read-write. Assume !vma is a shm mapping + */ + if (!vma || vma->vm_flags & VM_MAYSHARE) { + /* + * resv_map can not be NULL as hugetlb_reserve_pages is only + * called for inodes for which resv_maps were created (see + * hugetlbfs_get_inode). + */ + resv_map = inode_resv_map(inode); + + chg = region_chg(resv_map, from, to, ®ions_needed); + } else { + /* Private mapping. */ + resv_map = resv_map_alloc(); + if (!resv_map) + goto out_err; + + chg = to - from; + + set_vma_resv_map(vma, resv_map); + set_vma_resv_flags(vma, HPAGE_RESV_OWNER); + } + + if (chg < 0) + goto out_err; + + if (hugetlb_cgroup_charge_cgroup_rsvd(hstate_index(h), + chg * pages_per_huge_page(h), &h_cg) < 0) + goto out_err; + + if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) { + /* For private mappings, the hugetlb_cgroup uncharge info hangs + * of the resv_map. + */ + resv_map_set_hugetlb_cgroup_uncharge_info(resv_map, h_cg, h); + } + + /* + * There must be enough pages in the subpool for the mapping. If + * the subpool has a minimum size, there may be some global + * reservations already in place (gbl_reserve). + */ + gbl_reserve = hugepage_subpool_get_pages(spool, chg); + if (gbl_reserve < 0) + goto out_uncharge_cgroup; + + /* + * Check enough hugepages are available for the reservation. + * Hand the pages back to the subpool if there are not + */ + if (hugetlb_acct_memory(h, gbl_reserve) < 0) + goto out_put_pages; + + /* + * Account for the reservations made. Shared mappings record regions + * that have reservations as they are shared by multiple VMAs. + * When the last VMA disappears, the region map says how much + * the reservation was and the page cache tells how much of + * the reservation was consumed. Private mappings are per-VMA and + * only the consumed reservations are tracked. When the VMA + * disappears, the original reservation is the VMA size and the + * consumed reservations are stored in the map. Hence, nothing + * else has to be done for private mappings here + */ + if (!vma || vma->vm_flags & VM_MAYSHARE) { + add = region_add(resv_map, from, to, regions_needed, h, h_cg); + + if (unlikely(add < 0)) { + hugetlb_acct_memory(h, -gbl_reserve); + goto out_put_pages; + } else if (unlikely(chg > add)) { + /* + * pages in this range were added to the reserve + * map between region_chg and region_add. This + * indicates a race with alloc_huge_page. Adjust + * the subpool and reserve counts modified above + * based on the difference. + */ + long rsv_adjust; + + /* + * hugetlb_cgroup_uncharge_cgroup_rsvd() will put the + * reference to h_cg->css. See comment below for detail. + */ + hugetlb_cgroup_uncharge_cgroup_rsvd( + hstate_index(h), + (chg - add) * pages_per_huge_page(h), h_cg); + + rsv_adjust = hugepage_subpool_put_pages(spool, + chg - add); + hugetlb_acct_memory(h, -rsv_adjust); + } else if (h_cg) { + /* + * The file_regions will hold their own reference to + * h_cg->css. So we should release the reference held + * via hugetlb_cgroup_charge_cgroup_rsvd() when we are + * done. + */ + hugetlb_cgroup_put_rsvd_cgroup(h_cg); + } + } + return true; + +out_put_pages: + /* put back original number of pages, chg */ + (void)hugepage_subpool_put_pages(spool, chg); +out_uncharge_cgroup: + hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h), + chg * pages_per_huge_page(h), h_cg); +out_err: + hugetlb_vma_lock_free(vma); + if (!vma || vma->vm_flags & VM_MAYSHARE) + /* Only call region_abort if the region_chg succeeded but the + * region_add failed or didn't run. + */ + if (chg >= 0 && add < 0) + region_abort(resv_map, from, to, regions_needed); + if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + kref_put(&resv_map->refs, resv_map_release); + set_vma_resv_map(vma, NULL); + } + return false; +} + +long hugetlb_unreserve_pages(struct inode *inode, long start, long end, + long freed) +{ + struct hstate *h = hstate_inode(inode); + struct resv_map *resv_map = inode_resv_map(inode); + long chg = 0; + struct hugepage_subpool *spool = subpool_inode(inode); + long gbl_reserve; + + /* + * Since this routine can be called in the evict inode path for all + * hugetlbfs inodes, resv_map could be NULL. + */ + if (resv_map) { + chg = region_del(resv_map, start, end); + /* + * region_del() can fail in the rare case where a region + * must be split and another region descriptor can not be + * allocated. If end == LONG_MAX, it will not fail. + */ + if (chg < 0) + return chg; + } + + spin_lock(&inode->i_lock); + inode->i_blocks -= (blocks_per_huge_page(h) * freed); + spin_unlock(&inode->i_lock); + + /* + * If the subpool has a minimum size, the number of global + * reservations to be released may be adjusted. + * + * Note that !resv_map implies freed == 0. So (chg - freed) + * won't go negative. + */ + gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed)); + hugetlb_acct_memory(h, -gbl_reserve); + + return 0; +} + +#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE +static unsigned long page_table_shareable(struct vm_area_struct *svma, + struct vm_area_struct *vma, + unsigned long addr, pgoff_t idx) +{ + unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + + svma->vm_start; + unsigned long sbase = saddr & PUD_MASK; + unsigned long s_end = sbase + PUD_SIZE; + + /* Allow segments to share if only one is marked locked */ + unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK; + unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK; + + /* + * match the virtual addresses, permission and the alignment of the + * page table page. + * + * Also, vma_lock (vm_private_data) is required for sharing. + */ + if (pmd_index(addr) != pmd_index(saddr) || + vm_flags != svm_flags || + !range_in_vma(svma, sbase, s_end) || + !svma->vm_private_data) + return 0; + + return saddr; +} + +bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr) +{ + unsigned long start = addr & PUD_MASK; + unsigned long end = start + PUD_SIZE; + +#ifdef CONFIG_USERFAULTFD + if (uffd_disable_huge_pmd_share(vma)) + return false; +#endif + /* + * check on proper vm_flags and page table alignment + */ + if (!(vma->vm_flags & VM_MAYSHARE)) + return false; + if (!vma->vm_private_data) /* vma lock required for sharing */ + return false; + if (!range_in_vma(vma, start, end)) + return false; + return true; +} + +/* + * Determine if start,end range within vma could be mapped by shared pmd. + * If yes, adjust start and end to cover range associated with possible + * shared pmd mappings. + */ +void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, + unsigned long *start, unsigned long *end) +{ + unsigned long v_start = ALIGN(vma->vm_start, PUD_SIZE), + v_end = ALIGN_DOWN(vma->vm_end, PUD_SIZE); + + /* + * vma needs to span at least one aligned PUD size, and the range + * must be at least partially within in. + */ + if (!(vma->vm_flags & VM_MAYSHARE) || !(v_end > v_start) || + (*end <= v_start) || (*start >= v_end)) + return; + + /* Extend the range to be PUD aligned for a worst case scenario */ + if (*start > v_start) + *start = ALIGN_DOWN(*start, PUD_SIZE); + + if (*end < v_end) + *end = ALIGN(*end, PUD_SIZE); +} + +/* + * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc() + * and returns the corresponding pte. While this is not necessary for the + * !shared pmd case because we can allocate the pmd later as well, it makes the + * code much cleaner. pmd allocation is essential for the shared case because + * pud has to be populated inside the same i_mmap_rwsem section - otherwise + * racing tasks could either miss the sharing (see huge_pte_offset) or select a + * bad pmd for sharing. + */ +pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, pud_t *pud) +{ + struct address_space *mapping = vma->vm_file->f_mapping; + pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + + vma->vm_pgoff; + struct vm_area_struct *svma; + unsigned long saddr; + pte_t *spte = NULL; + pte_t *pte; + spinlock_t *ptl; + + i_mmap_lock_read(mapping); + vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) { + if (svma == vma) + continue; + + saddr = page_table_shareable(svma, vma, addr, idx); + if (saddr) { + spte = huge_pte_offset(svma->vm_mm, saddr, + vma_mmu_pagesize(svma)); + if (spte) { + get_page(virt_to_page(spte)); + break; + } + } + } + + if (!spte) + goto out; + + ptl = huge_pte_lock(hstate_vma(vma), mm, spte); + if (pud_none(*pud)) { + pud_populate(mm, pud, + (pmd_t *)((unsigned long)spte & PAGE_MASK)); + mm_inc_nr_pmds(mm); + } else { + put_page(virt_to_page(spte)); + } + spin_unlock(ptl); +out: + pte = (pte_t *)pmd_alloc(mm, pud, addr); + i_mmap_unlock_read(mapping); + return pte; +} + +/* + * unmap huge page backed by shared pte. + * + * Hugetlb pte page is ref counted at the time of mapping. If pte is shared + * indicated by page_count > 1, unmap is achieved by clearing pud and + * decrementing the ref count. If count == 1, the pte page is not shared. + * + * Called with page table lock held. + * + * returns: 1 successfully unmapped a shared pte page + * 0 the underlying pte page is not shared, or it is the last user + */ +int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) +{ + pgd_t *pgd = pgd_offset(mm, addr); + p4d_t *p4d = p4d_offset(pgd, addr); + pud_t *pud = pud_offset(p4d, addr); + + i_mmap_assert_write_locked(vma->vm_file->f_mapping); + hugetlb_vma_assert_locked(vma); + BUG_ON(page_count(virt_to_page(ptep)) == 0); + if (page_count(virt_to_page(ptep)) == 1) + return 0; + + pud_clear(pud); + put_page(virt_to_page(ptep)); + mm_dec_nr_pmds(mm); + return 1; +} + +#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ + +pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, pud_t *pud) +{ + return NULL; +} + +int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) +{ + return 0; +} + +void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, + unsigned long *start, unsigned long *end) +{ +} + +bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr) +{ + return false; +} +#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ + +#ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB +pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long addr, unsigned long sz) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pte_t *pte = NULL; + + pgd = pgd_offset(mm, addr); + p4d = p4d_alloc(mm, pgd, addr); + if (!p4d) + return NULL; + pud = pud_alloc(mm, p4d, addr); + if (pud) { + if (sz == PUD_SIZE) { + pte = (pte_t *)pud; + } else { + BUG_ON(sz != PMD_SIZE); + if (want_pmd_share(vma, addr) && pud_none(*pud)) + pte = huge_pmd_share(mm, vma, addr, pud); + else + pte = (pte_t *)pmd_alloc(mm, pud, addr); + } + } + BUG_ON(pte && pte_present(*pte) && !pte_huge(*pte)); + + return pte; +} + +/* + * huge_pte_offset() - Walk the page table to resolve the hugepage + * entry at address @addr + * + * Return: Pointer to page table entry (PUD or PMD) for + * address @addr, or NULL if a !p*d_present() entry is encountered and the + * size @sz doesn't match the hugepage size at this level of the page + * table. + */ +pte_t *huge_pte_offset(struct mm_struct *mm, + unsigned long addr, unsigned long sz) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + pgd = pgd_offset(mm, addr); + if (!pgd_present(*pgd)) + return NULL; + p4d = p4d_offset(pgd, addr); + if (!p4d_present(*p4d)) + return NULL; + + pud = pud_offset(p4d, addr); + if (sz == PUD_SIZE) + /* must be pud huge, non-present or none */ + return (pte_t *)pud; + if (!pud_present(*pud)) + return NULL; + /* must have a valid entry and size to go further */ + + pmd = pmd_offset(pud, addr); + /* must be pmd huge, non-present or none */ + return (pte_t *)pmd; +} + +/* + * Return a mask that can be used to update an address to the last huge + * page in a page table page mapping size. Used to skip non-present + * page table entries when linearly scanning address ranges. Architectures + * with unique huge page to page table relationships can define their own + * version of this routine. + */ +unsigned long hugetlb_mask_last_page(struct hstate *h) +{ + unsigned long hp_size = huge_page_size(h); + + if (hp_size == PUD_SIZE) + return P4D_SIZE - PUD_SIZE; + else if (hp_size == PMD_SIZE) + return PUD_SIZE - PMD_SIZE; + else + return 0UL; +} + +#else + +/* See description above. Architectures can provide their own version. */ +__weak unsigned long hugetlb_mask_last_page(struct hstate *h) +{ +#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE + if (huge_page_size(h) == PMD_SIZE) + return PUD_SIZE - PMD_SIZE; +#endif + return 0UL; +} + +#endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */ + +/* + * These functions are overwritable if your architecture needs its own + * behavior. + */ +struct page * __weak +follow_huge_addr(struct mm_struct *mm, unsigned long address, + int write) +{ + return ERR_PTR(-EINVAL); +} + +struct page * __weak +follow_huge_pd(struct vm_area_struct *vma, + unsigned long address, hugepd_t hpd, int flags, int pdshift) +{ + WARN(1, "hugepd follow called with no support for hugepage directory format\n"); + return NULL; +} + +struct page * __weak +follow_huge_pmd_pte(struct vm_area_struct *vma, unsigned long address, int flags) +{ + struct hstate *h = hstate_vma(vma); + struct mm_struct *mm = vma->vm_mm; + struct page *page = NULL; + spinlock_t *ptl; + pte_t *ptep, pte; + + /* + * FOLL_PIN is not supported for follow_page(). Ordinary GUP goes via + * follow_hugetlb_page(). + */ + if (WARN_ON_ONCE(flags & FOLL_PIN)) + return NULL; + +retry: + ptep = huge_pte_offset(mm, address, huge_page_size(h)); + if (!ptep) + return NULL; + + ptl = huge_pte_lock(h, mm, ptep); + pte = huge_ptep_get(ptep); + if (pte_present(pte)) { + page = pte_page(pte) + + ((address & ~huge_page_mask(h)) >> PAGE_SHIFT); + /* + * try_grab_page() should always succeed here, because: a) we + * hold the pmd (ptl) lock, and b) we've just checked that the + * huge pmd (head) page is present in the page tables. The ptl + * prevents the head page and tail pages from being rearranged + * in any way. So this page must be available at this point, + * unless the page refcount overflowed: + */ + if (WARN_ON_ONCE(!try_grab_page(page, flags))) { + page = NULL; + goto out; + } + } else { + if (is_hugetlb_entry_migration(pte)) { + spin_unlock(ptl); + __migration_entry_wait_huge(ptep, ptl); + goto retry; + } + /* + * hwpoisoned entry is treated as no_page_table in + * follow_page_mask(). + */ + } +out: + spin_unlock(ptl); + return page; +} + +struct page * __weak +follow_huge_pud(struct mm_struct *mm, unsigned long address, + pud_t *pud, int flags) +{ + struct page *page = NULL; + spinlock_t *ptl; + pte_t pte; + + if (WARN_ON_ONCE(flags & FOLL_PIN)) + return NULL; + +retry: + ptl = huge_pte_lock(hstate_sizelog(PUD_SHIFT), mm, (pte_t *)pud); + if (!pud_huge(*pud)) + goto out; + pte = huge_ptep_get((pte_t *)pud); + if (pte_present(pte)) { + page = pud_page(*pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(!try_grab_page(page, flags))) { + page = NULL; + goto out; + } + } else { + if (is_hugetlb_entry_migration(pte)) { + spin_unlock(ptl); + __migration_entry_wait(mm, (pte_t *)pud, ptl); + goto retry; + } + /* + * hwpoisoned entry is treated as no_page_table in + * follow_page_mask(). + */ + } +out: + spin_unlock(ptl); + return page; +} + +struct page * __weak +follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int flags) +{ + if (flags & (FOLL_GET | FOLL_PIN)) + return NULL; + + return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT); +} + +int isolate_hugetlb(struct page *page, struct list_head *list) +{ + int ret = 0; + + spin_lock_irq(&hugetlb_lock); + if (!PageHeadHuge(page) || + !HPageMigratable(page) || + !get_page_unless_zero(page)) { + ret = -EBUSY; + goto unlock; + } + ClearHPageMigratable(page); + list_move_tail(&page->lru, list); +unlock: + spin_unlock_irq(&hugetlb_lock); + return ret; +} + +int get_hwpoison_huge_page(struct page *page, bool *hugetlb) +{ + int ret = 0; + + *hugetlb = false; + spin_lock_irq(&hugetlb_lock); + if (PageHeadHuge(page)) { + *hugetlb = true; + if (HPageFreed(page)) + ret = 0; + else if (HPageMigratable(page)) + ret = get_page_unless_zero(page); + else + ret = -EBUSY; + } + spin_unlock_irq(&hugetlb_lock); + return ret; +} + +int get_huge_page_for_hwpoison(unsigned long pfn, int flags) +{ + int ret; + + spin_lock_irq(&hugetlb_lock); + ret = __get_huge_page_for_hwpoison(pfn, flags); + spin_unlock_irq(&hugetlb_lock); + return ret; +} + +void putback_active_hugepage(struct page *page) +{ + spin_lock_irq(&hugetlb_lock); + SetHPageMigratable(page); + list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist); + spin_unlock_irq(&hugetlb_lock); + put_page(page); +} + +void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason) +{ + struct hstate *h = page_hstate(oldpage); + + hugetlb_cgroup_migrate(oldpage, newpage); + set_page_owner_migrate_reason(newpage, reason); + + /* + * transfer temporary state of the new huge page. This is + * reverse to other transitions because the newpage is going to + * be final while the old one will be freed so it takes over + * the temporary status. + * + * Also note that we have to transfer the per-node surplus state + * here as well otherwise the global surplus count will not match + * the per-node's. + */ + if (HPageTemporary(newpage)) { + int old_nid = page_to_nid(oldpage); + int new_nid = page_to_nid(newpage); + + SetHPageTemporary(oldpage); + ClearHPageTemporary(newpage); + + /* + * There is no need to transfer the per-node surplus state + * when we do not cross the node. + */ + if (new_nid == old_nid) + return; + spin_lock_irq(&hugetlb_lock); + if (h->surplus_huge_pages_node[old_nid]) { + h->surplus_huge_pages_node[old_nid]--; + h->surplus_huge_pages_node[new_nid]++; + } + spin_unlock_irq(&hugetlb_lock); + } +} + +static void hugetlb_unshare_pmds(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + struct mm_struct *mm = vma->vm_mm; + struct mmu_notifier_range range; + unsigned long address; + spinlock_t *ptl; + pte_t *ptep; + + if (!(vma->vm_flags & VM_MAYSHARE)) + return; + + if (start >= end) + return; + + flush_cache_range(vma, start, end); + /* + * No need to call adjust_range_if_pmd_sharing_possible(), because + * we have already done the PUD_SIZE alignment. + */ + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, + start, end); + mmu_notifier_invalidate_range_start(&range); + hugetlb_vma_lock_write(vma); + i_mmap_lock_write(vma->vm_file->f_mapping); + for (address = start; address < end; address += PUD_SIZE) { + ptep = huge_pte_offset(mm, address, sz); + if (!ptep) + continue; + ptl = huge_pte_lock(h, mm, ptep); + huge_pmd_unshare(mm, vma, address, ptep); + spin_unlock(ptl); + } + flush_hugetlb_tlb_range(vma, start, end); + i_mmap_unlock_write(vma->vm_file->f_mapping); + hugetlb_vma_unlock_write(vma); + /* + * No need to call mmu_notifier_invalidate_range(), see + * Documentation/mm/mmu_notifier.rst. + */ + mmu_notifier_invalidate_range_end(&range); +} + +/* + * This function will unconditionally remove all the shared pmd pgtable entries + * within the specific vma for a hugetlbfs memory range. + */ +void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) +{ + hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE), + ALIGN_DOWN(vma->vm_end, PUD_SIZE)); +} + +#ifdef CONFIG_CMA +static bool cma_reserve_called __initdata; + +static int __init cmdline_parse_hugetlb_cma(char *p) +{ + int nid, count = 0; + unsigned long tmp; + char *s = p; + + while (*s) { + if (sscanf(s, "%lu%n", &tmp, &count) != 1) + break; + + if (s[count] == ':') { + if (tmp >= MAX_NUMNODES) + break; + nid = array_index_nospec(tmp, MAX_NUMNODES); + + s += count + 1; + tmp = memparse(s, &s); + hugetlb_cma_size_in_node[nid] = tmp; + hugetlb_cma_size += tmp; + + /* + * Skip the separator if have one, otherwise + * break the parsing. + */ + if (*s == ',') + s++; + else + break; + } else { + hugetlb_cma_size = memparse(p, &p); + break; + } + } + + return 0; +} + +early_param("hugetlb_cma", cmdline_parse_hugetlb_cma); + +void __init hugetlb_cma_reserve(int order) +{ + unsigned long size, reserved, per_node; + bool node_specific_cma_alloc = false; + int nid; + + cma_reserve_called = true; + + if (!hugetlb_cma_size) + return; + + for (nid = 0; nid < MAX_NUMNODES; nid++) { + if (hugetlb_cma_size_in_node[nid] == 0) + continue; + + if (!node_online(nid)) { + pr_warn("hugetlb_cma: invalid node %d specified\n", nid); + hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; + hugetlb_cma_size_in_node[nid] = 0; + continue; + } + + if (hugetlb_cma_size_in_node[nid] < (PAGE_SIZE << order)) { + pr_warn("hugetlb_cma: cma area of node %d should be at least %lu MiB\n", + nid, (PAGE_SIZE << order) / SZ_1M); + hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; + hugetlb_cma_size_in_node[nid] = 0; + } else { + node_specific_cma_alloc = true; + } + } + + /* Validate the CMA size again in case some invalid nodes specified. */ + if (!hugetlb_cma_size) + return; + + if (hugetlb_cma_size < (PAGE_SIZE << order)) { + pr_warn("hugetlb_cma: cma area should be at least %lu MiB\n", + (PAGE_SIZE << order) / SZ_1M); + hugetlb_cma_size = 0; + return; + } + + if (!node_specific_cma_alloc) { + /* + * If 3 GB area is requested on a machine with 4 numa nodes, + * let's allocate 1 GB on first three nodes and ignore the last one. + */ + per_node = DIV_ROUND_UP(hugetlb_cma_size, nr_online_nodes); + pr_info("hugetlb_cma: reserve %lu MiB, up to %lu MiB per node\n", + hugetlb_cma_size / SZ_1M, per_node / SZ_1M); + } + + reserved = 0; + for_each_online_node(nid) { + int res; + char name[CMA_MAX_NAME]; + + if (node_specific_cma_alloc) { + if (hugetlb_cma_size_in_node[nid] == 0) + continue; + + size = hugetlb_cma_size_in_node[nid]; + } else { + size = min(per_node, hugetlb_cma_size - reserved); + } + + size = round_up(size, PAGE_SIZE << order); + + snprintf(name, sizeof(name), "hugetlb%d", nid); + /* + * Note that 'order per bit' is based on smallest size that + * may be returned to CMA allocator in the case of + * huge page demotion. + */ + res = cma_declare_contiguous_nid(0, size, 0, + PAGE_SIZE << HUGETLB_PAGE_ORDER, + 0, false, name, + &hugetlb_cma[nid], nid); + if (res) { + pr_warn("hugetlb_cma: reservation failed: err %d, node %d", + res, nid); + continue; + } + + reserved += size; + pr_info("hugetlb_cma: reserved %lu MiB on node %d\n", + size / SZ_1M, nid); + + if (reserved >= hugetlb_cma_size) + break; + } + + if (!reserved) + /* + * hugetlb_cma_size is used to determine if allocations from + * cma are possible. Set to zero if no cma regions are set up. + */ + hugetlb_cma_size = 0; +} + +static void __init hugetlb_cma_check(void) +{ + if (!hugetlb_cma_size || cma_reserve_called) + return; + + pr_warn("hugetlb_cma: the option isn't supported by current arch\n"); +} + +#endif /* CONFIG_CMA */ |