diff options
Diffstat (limited to 'mm/hugetlb_vmemmap.c')
| -rw-r--r-- | mm/hugetlb_vmemmap.c | 301 |
1 files changed, 252 insertions, 49 deletions
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 4b9734777f..87818ee7f0 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -13,6 +13,7 @@ #include <linux/pgtable.h> #include <linux/moduleparam.h> #include <linux/bootmem_info.h> +#include <linux/mmdebug.h> #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include "hugetlb_vmemmap.h" @@ -26,6 +27,8 @@ * @reuse_addr: the virtual address of the @reuse_page page. * @vmemmap_pages: the list head of the vmemmap pages that can be freed * or is mapped from. + * @flags: used to modify behavior in vmemmap page table walking + * operations. */ struct vmemmap_remap_walk { void (*remap_pte)(pte_t *pte, unsigned long addr, @@ -34,9 +37,15 @@ struct vmemmap_remap_walk { struct page *reuse_page; unsigned long reuse_addr; struct list_head *vmemmap_pages; + +/* Skip the TLB flush when we split the PMD */ +#define VMEMMAP_SPLIT_NO_TLB_FLUSH BIT(0) +/* Skip the TLB flush when we remap the PTE */ +#define VMEMMAP_REMAP_NO_TLB_FLUSH BIT(1) + unsigned long flags; }; -static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start) +static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start, bool flush) { pmd_t __pmd; int i; @@ -79,7 +88,8 @@ static int split_vmemmap_huge_pmd(pmd_t *pmd, unsigned long start) /* Make pte visible before pmd. See comment in pmd_install(). */ smp_wmb(); pmd_populate_kernel(&init_mm, pmd, pgtable); - flush_tlb_kernel_range(start, start + PMD_SIZE); + if (flush) + flush_tlb_kernel_range(start, start + PMD_SIZE); } else { pte_free_kernel(&init_mm, pgtable); } @@ -126,11 +136,20 @@ static int vmemmap_pmd_range(pud_t *pud, unsigned long addr, do { int ret; - ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK); + ret = split_vmemmap_huge_pmd(pmd, addr & PMD_MASK, + !(walk->flags & VMEMMAP_SPLIT_NO_TLB_FLUSH)); if (ret) return ret; next = pmd_addr_end(addr, end); + + /* + * We are only splitting, not remapping the hugetlb vmemmap + * pages. + */ + if (!walk->remap_pte) + continue; + vmemmap_pte_range(pmd, addr, next, walk); } while (pmd++, addr = next, addr != end); @@ -197,7 +216,8 @@ static int vmemmap_remap_range(unsigned long start, unsigned long end, return ret; } while (pgd++, addr = next, addr != end); - flush_tlb_kernel_range(start, end); + if (walk->remap_pte && !(walk->flags & VMEMMAP_REMAP_NO_TLB_FLUSH)) + flush_tlb_kernel_range(start, end); return 0; } @@ -250,7 +270,7 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, } entry = mk_pte(walk->reuse_page, pgprot); - list_add_tail(&page->lru, walk->vmemmap_pages); + list_add(&page->lru, walk->vmemmap_pages); set_pte_at(&init_mm, addr, pte, entry); } @@ -297,6 +317,36 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, } /** + * vmemmap_remap_split - split the vmemmap virtual address range [@start, @end) + * backing PMDs of the directmap into PTEs + * @start: start address of the vmemmap virtual address range that we want + * to remap. + * @end: end address of the vmemmap virtual address range that we want to + * remap. + * @reuse: reuse address. + * + * Return: %0 on success, negative error code otherwise. + */ +static int vmemmap_remap_split(unsigned long start, unsigned long end, + unsigned long reuse) +{ + int ret; + struct vmemmap_remap_walk walk = { + .remap_pte = NULL, + .flags = VMEMMAP_SPLIT_NO_TLB_FLUSH, + }; + + /* See the comment in the vmemmap_remap_free(). */ + BUG_ON(start - reuse != PAGE_SIZE); + + mmap_read_lock(&init_mm); + ret = vmemmap_remap_range(reuse, end, &walk); + mmap_read_unlock(&init_mm); + + return ret; +} + +/** * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end) * to the page which @reuse is mapped to, then free vmemmap * which the range are mapped to. @@ -305,22 +355,26 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, * @end: end address of the vmemmap virtual address range that we want to * remap. * @reuse: reuse address. + * @vmemmap_pages: list to deposit vmemmap pages to be freed. It is callers + * responsibility to free pages. + * @flags: modifications to vmemmap_remap_walk flags * * Return: %0 on success, negative error code otherwise. */ static int vmemmap_remap_free(unsigned long start, unsigned long end, - unsigned long reuse) + unsigned long reuse, + struct list_head *vmemmap_pages, + unsigned long flags) { int ret; - LIST_HEAD(vmemmap_pages); struct vmemmap_remap_walk walk = { .remap_pte = vmemmap_remap_pte, .reuse_addr = reuse, - .vmemmap_pages = &vmemmap_pages, + .vmemmap_pages = vmemmap_pages, + .flags = flags, }; - int nid = page_to_nid((struct page *)start); - gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY | - __GFP_NOWARN; + int nid = page_to_nid((struct page *)reuse); + gfp_t gfp_mask = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN; /* * Allocate a new head vmemmap page to avoid breaking a contiguous @@ -334,7 +388,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, if (walk.reuse_page) { copy_page(page_to_virt(walk.reuse_page), (void *)walk.reuse_addr); - list_add(&walk.reuse_page->lru, &vmemmap_pages); + list_add(&walk.reuse_page->lru, vmemmap_pages); } /* @@ -365,22 +419,21 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, walk = (struct vmemmap_remap_walk) { .remap_pte = vmemmap_restore_pte, .reuse_addr = reuse, - .vmemmap_pages = &vmemmap_pages, + .vmemmap_pages = vmemmap_pages, + .flags = 0, }; vmemmap_remap_range(reuse, end, &walk); } mmap_read_unlock(&init_mm); - free_vmemmap_page_list(&vmemmap_pages); - return ret; } static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, struct list_head *list) { - gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_THISNODE; + gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL; unsigned long nr_pages = (end - start) >> PAGE_SHIFT; int nid = page_to_nid((struct page *)start); struct page *page, *next; @@ -389,7 +442,7 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, page = alloc_pages_node(nid, gfp_mask, 0); if (!page) goto out; - list_add_tail(&page->lru, list); + list_add(&page->lru, list); } return 0; @@ -408,17 +461,19 @@ out: * @end: end address of the vmemmap virtual address range that we want to * remap. * @reuse: reuse address. + * @flags: modifications to vmemmap_remap_walk flags * * Return: %0 on success, negative error code otherwise. */ static int vmemmap_remap_alloc(unsigned long start, unsigned long end, - unsigned long reuse) + unsigned long reuse, unsigned long flags) { LIST_HEAD(vmemmap_pages); struct vmemmap_remap_walk walk = { .remap_pte = vmemmap_restore_pte, .reuse_addr = reuse, .vmemmap_pages = &vmemmap_pages, + .flags = flags, }; /* See the comment in the vmemmap_remap_free(). */ @@ -440,23 +495,15 @@ EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key); static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON); core_param(hugetlb_free_vmemmap, vmemmap_optimize_enabled, bool, 0); -/** - * hugetlb_vmemmap_restore - restore previously optimized (by - * hugetlb_vmemmap_optimize()) vmemmap pages which - * will be reallocated and remapped. - * @h: struct hstate. - * @head: the head page whose vmemmap pages will be restored. - * - * Return: %0 if @head's vmemmap pages have been reallocated and remapped, - * negative error code otherwise. - */ -int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head) +static int __hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio, unsigned long flags) { int ret; + struct page *head = &folio->page; unsigned long vmemmap_start = (unsigned long)head, vmemmap_end; unsigned long vmemmap_reuse; - if (!HPageVmemmapOptimized(head)) + VM_WARN_ON_ONCE(!PageHuge(head)); + if (!folio_test_hugetlb_vmemmap_optimized(folio)) return 0; vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h); @@ -470,18 +517,77 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head) * When a HugeTLB page is freed to the buddy allocator, previously * discarded vmemmap pages must be allocated and remapping. */ - ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse); + ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse, flags); if (!ret) { - ClearHPageVmemmapOptimized(head); + folio_clear_hugetlb_vmemmap_optimized(folio); static_branch_dec(&hugetlb_optimize_vmemmap_key); } return ret; } +/** + * hugetlb_vmemmap_restore_folio - restore previously optimized (by + * hugetlb_vmemmap_optimize_folio()) vmemmap pages which + * will be reallocated and remapped. + * @h: struct hstate. + * @folio: the folio whose vmemmap pages will be restored. + * + * Return: %0 if @folio's vmemmap pages have been reallocated and remapped, + * negative error code otherwise. + */ +int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio) +{ + return __hugetlb_vmemmap_restore_folio(h, folio, 0); +} + +/** + * hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list. + * @h: hstate. + * @folio_list: list of folios. + * @non_hvo_folios: Output list of folios for which vmemmap exists. + * + * Return: number of folios for which vmemmap was restored, or an error code + * if an error was encountered restoring vmemmap for a folio. + * Folios that have vmemmap are moved to the non_hvo_folios + * list. Processing of entries stops when the first error is + * encountered. The folio that experienced the error and all + * non-processed folios will remain on folio_list. + */ +long hugetlb_vmemmap_restore_folios(const struct hstate *h, + struct list_head *folio_list, + struct list_head *non_hvo_folios) +{ + struct folio *folio, *t_folio; + long restored = 0; + long ret = 0; + + list_for_each_entry_safe(folio, t_folio, folio_list, lru) { + if (folio_test_hugetlb_vmemmap_optimized(folio)) { + ret = __hugetlb_vmemmap_restore_folio(h, folio, + VMEMMAP_REMAP_NO_TLB_FLUSH); + if (ret) + break; + restored++; + } + + /* Add non-optimized folios to output list */ + list_move(&folio->lru, non_hvo_folios); + } + + if (restored) + flush_tlb_all(); + if (!ret) + ret = restored; + return ret; +} + /* Return true iff a HugeTLB whose vmemmap should and can be optimized. */ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *head) { + if (HPageVmemmapOptimized((struct page *)head)) + return false; + if (!READ_ONCE(vmemmap_optimize_enabled)) return false; @@ -535,39 +641,136 @@ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *h return true; } +static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h, + struct folio *folio, + struct list_head *vmemmap_pages, + unsigned long flags) +{ + int ret = 0; + struct page *head = &folio->page; + unsigned long vmemmap_start = (unsigned long)head, vmemmap_end; + unsigned long vmemmap_reuse; + + VM_WARN_ON_ONCE(!PageHuge(head)); + if (!vmemmap_should_optimize(h, head)) + return ret; + + static_branch_inc(&hugetlb_optimize_vmemmap_key); + /* + * Very Subtle + * If VMEMMAP_REMAP_NO_TLB_FLUSH is set, TLB flushing is not performed + * immediately after remapping. As a result, subsequent accesses + * and modifications to struct pages associated with the hugetlb + * page could be to the OLD struct pages. Set the vmemmap optimized + * flag here so that it is copied to the new head page. This keeps + * the old and new struct pages in sync. + * If there is an error during optimization, we will immediately FLUSH + * the TLB and clear the flag below. + */ + folio_set_hugetlb_vmemmap_optimized(folio); + + vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h); + vmemmap_reuse = vmemmap_start; + vmemmap_start += HUGETLB_VMEMMAP_RESERVE_SIZE; + + /* + * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end) + * to the page which @vmemmap_reuse is mapped to. Add pages previously + * mapping the range to vmemmap_pages list so that they can be freed by + * the caller. + */ + ret = vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, + vmemmap_pages, flags); + if (ret) { + static_branch_dec(&hugetlb_optimize_vmemmap_key); + folio_clear_hugetlb_vmemmap_optimized(folio); + } + + return ret; +} + /** - * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages. + * hugetlb_vmemmap_optimize_folio - optimize @folio's vmemmap pages. * @h: struct hstate. - * @head: the head page whose vmemmap pages will be optimized. + * @folio: the folio whose vmemmap pages will be optimized. * - * This function only tries to optimize @head's vmemmap pages and does not + * This function only tries to optimize @folio's vmemmap pages and does not * guarantee that the optimization will succeed after it returns. The caller - * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages - * have been optimized. + * can use folio_test_hugetlb_vmemmap_optimized(@folio) to detect if @folio's + * vmemmap pages have been optimized. */ -void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) +void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio) +{ + LIST_HEAD(vmemmap_pages); + + __hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, 0); + free_vmemmap_page_list(&vmemmap_pages); +} + +static int hugetlb_vmemmap_split(const struct hstate *h, struct page *head) { unsigned long vmemmap_start = (unsigned long)head, vmemmap_end; unsigned long vmemmap_reuse; if (!vmemmap_should_optimize(h, head)) - return; - - static_branch_inc(&hugetlb_optimize_vmemmap_key); + return 0; vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h); vmemmap_reuse = vmemmap_start; vmemmap_start += HUGETLB_VMEMMAP_RESERVE_SIZE; /* - * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end) - * to the page which @vmemmap_reuse is mapped to, then free the pages - * which the range [@vmemmap_start, @vmemmap_end] is mapped to. + * Split PMDs on the vmemmap virtual address range [@vmemmap_start, + * @vmemmap_end] */ - if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse)) - static_branch_dec(&hugetlb_optimize_vmemmap_key); - else - SetHPageVmemmapOptimized(head); + return vmemmap_remap_split(vmemmap_start, vmemmap_end, vmemmap_reuse); +} + +void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list) +{ + struct folio *folio; + LIST_HEAD(vmemmap_pages); + + list_for_each_entry(folio, folio_list, lru) { + int ret = hugetlb_vmemmap_split(h, &folio->page); + + /* + * Spliting the PMD requires allocating a page, thus lets fail + * early once we encounter the first OOM. No point in retrying + * as it can be dynamically done on remap with the memory + * we get back from the vmemmap deduplication. + */ + if (ret == -ENOMEM) + break; + } + + flush_tlb_all(); + + list_for_each_entry(folio, folio_list, lru) { + int ret = __hugetlb_vmemmap_optimize_folio(h, folio, + &vmemmap_pages, + VMEMMAP_REMAP_NO_TLB_FLUSH); + + /* + * Pages to be freed may have been accumulated. If we + * encounter an ENOMEM, free what we have and try again. + * This can occur in the case that both spliting fails + * halfway and head page allocation also failed. In this + * case __hugetlb_vmemmap_optimize_folio() would free memory + * allowing more vmemmap remaps to occur. + */ + if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) { + flush_tlb_all(); + free_vmemmap_page_list(&vmemmap_pages); + INIT_LIST_HEAD(&vmemmap_pages); + __hugetlb_vmemmap_optimize_folio(h, folio, + &vmemmap_pages, + VMEMMAP_REMAP_NO_TLB_FLUSH); + } + } + + flush_tlb_all(); + free_vmemmap_page_list(&vmemmap_pages); } static struct ctl_table hugetlb_vmemmap_sysctls[] = { @@ -586,7 +789,7 @@ static int __init hugetlb_vmemmap_init(void) const struct hstate *h; /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */ - BUILD_BUG_ON(__NR_USED_SUBPAGE * sizeof(struct page) > HUGETLB_VMEMMAP_RESERVE_SIZE); + BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES); for_each_hstate(h) { if (hugetlb_vmemmap_optimizable(h)) { |