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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /mm/memory.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c6018
1 files changed, 6018 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
new file mode 100644
index 000000000..fc8b264ec
--- /dev/null
+++ b/mm/memory.c
@@ -0,0 +1,6018 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/mm/memory.c
+ *
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ */
+
+/*
+ * demand-loading started 01.12.91 - seems it is high on the list of
+ * things wanted, and it should be easy to implement. - Linus
+ */
+
+/*
+ * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
+ * pages started 02.12.91, seems to work. - Linus.
+ *
+ * Tested sharing by executing about 30 /bin/sh: under the old kernel it
+ * would have taken more than the 6M I have free, but it worked well as
+ * far as I could see.
+ *
+ * Also corrected some "invalidate()"s - I wasn't doing enough of them.
+ */
+
+/*
+ * Real VM (paging to/from disk) started 18.12.91. Much more work and
+ * thought has to go into this. Oh, well..
+ * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
+ * Found it. Everything seems to work now.
+ * 20.12.91 - Ok, making the swap-device changeable like the root.
+ */
+
+/*
+ * 05.04.94 - Multi-page memory management added for v1.1.
+ * Idea by Alex Bligh (alex@cconcepts.co.uk)
+ *
+ * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
+ * (Gerhard.Wichert@pdb.siemens.de)
+ *
+ * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/mm.h>
+#include <linux/mm_inline.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/coredump.h>
+#include <linux/sched/numa_balancing.h>
+#include <linux/sched/task.h>
+#include <linux/hugetlb.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/memremap.h>
+#include <linux/kmsan.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/export.h>
+#include <linux/delayacct.h>
+#include <linux/init.h>
+#include <linux/pfn_t.h>
+#include <linux/writeback.h>
+#include <linux/memcontrol.h>
+#include <linux/mmu_notifier.h>
+#include <linux/swapops.h>
+#include <linux/elf.h>
+#include <linux/gfp.h>
+#include <linux/migrate.h>
+#include <linux/string.h>
+#include <linux/memory-tiers.h>
+#include <linux/debugfs.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/dax.h>
+#include <linux/oom.h>
+#include <linux/numa.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/vmalloc.h>
+#include <linux/sched/sysctl.h>
+
+#include <trace/events/kmem.h>
+
+#include <asm/io.h>
+#include <asm/mmu_context.h>
+#include <asm/pgalloc.h>
+#include <linux/uaccess.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+
+#include "pgalloc-track.h"
+#include "internal.h"
+#include "swap.h"
+
+#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
+#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
+#endif
+
+#ifndef CONFIG_NUMA
+unsigned long max_mapnr;
+EXPORT_SYMBOL(max_mapnr);
+
+struct page *mem_map;
+EXPORT_SYMBOL(mem_map);
+#endif
+
+static vm_fault_t do_fault(struct vm_fault *vmf);
+
+/*
+ * A number of key systems in x86 including ioremap() rely on the assumption
+ * that high_memory defines the upper bound on direct map memory, then end
+ * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
+ * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
+ * and ZONE_HIGHMEM.
+ */
+void *high_memory;
+EXPORT_SYMBOL(high_memory);
+
+/*
+ * Randomize the address space (stacks, mmaps, brk, etc.).
+ *
+ * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
+ * as ancient (libc5 based) binaries can segfault. )
+ */
+int randomize_va_space __read_mostly =
+#ifdef CONFIG_COMPAT_BRK
+ 1;
+#else
+ 2;
+#endif
+
+#ifndef arch_wants_old_prefaulted_pte
+static inline bool arch_wants_old_prefaulted_pte(void)
+{
+ /*
+ * Transitioning a PTE from 'old' to 'young' can be expensive on
+ * some architectures, even if it's performed in hardware. By
+ * default, "false" means prefaulted entries will be 'young'.
+ */
+ return false;
+}
+#endif
+
+static int __init disable_randmaps(char *s)
+{
+ randomize_va_space = 0;
+ return 1;
+}
+__setup("norandmaps", disable_randmaps);
+
+unsigned long zero_pfn __read_mostly;
+EXPORT_SYMBOL(zero_pfn);
+
+unsigned long highest_memmap_pfn __read_mostly;
+
+/*
+ * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
+ */
+static int __init init_zero_pfn(void)
+{
+ zero_pfn = page_to_pfn(ZERO_PAGE(0));
+ return 0;
+}
+early_initcall(init_zero_pfn);
+
+void mm_trace_rss_stat(struct mm_struct *mm, int member, long count)
+{
+ trace_rss_stat(mm, member, count);
+}
+
+#if defined(SPLIT_RSS_COUNTING)
+
+void sync_mm_rss(struct mm_struct *mm)
+{
+ int i;
+
+ for (i = 0; i < NR_MM_COUNTERS; i++) {
+ if (current->rss_stat.count[i]) {
+ add_mm_counter(mm, i, current->rss_stat.count[i]);
+ current->rss_stat.count[i] = 0;
+ }
+ }
+ current->rss_stat.events = 0;
+}
+
+static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
+{
+ struct task_struct *task = current;
+
+ if (likely(task->mm == mm))
+ task->rss_stat.count[member] += val;
+ else
+ add_mm_counter(mm, member, val);
+}
+#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
+#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
+
+/* sync counter once per 64 page faults */
+#define TASK_RSS_EVENTS_THRESH (64)
+static void check_sync_rss_stat(struct task_struct *task)
+{
+ if (unlikely(task != current))
+ return;
+ if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
+ sync_mm_rss(task->mm);
+}
+#else /* SPLIT_RSS_COUNTING */
+
+#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
+#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
+
+static void check_sync_rss_stat(struct task_struct *task)
+{
+}
+
+#endif /* SPLIT_RSS_COUNTING */
+
+/*
+ * Note: this doesn't free the actual pages themselves. That
+ * has been handled earlier when unmapping all the memory regions.
+ */
+static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
+ unsigned long addr)
+{
+ pgtable_t token = pmd_pgtable(*pmd);
+ pmd_clear(pmd);
+ pte_free_tlb(tlb, token, addr);
+ mm_dec_nr_ptes(tlb->mm);
+}
+
+static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+ unsigned long addr, unsigned long end,
+ unsigned long floor, unsigned long ceiling)
+{
+ pmd_t *pmd;
+ unsigned long next;
+ unsigned long start;
+
+ start = addr;
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none_or_clear_bad(pmd))
+ continue;
+ free_pte_range(tlb, pmd, addr);
+ } while (pmd++, addr = next, addr != end);
+
+ start &= PUD_MASK;
+ if (start < floor)
+ return;
+ if (ceiling) {
+ ceiling &= PUD_MASK;
+ if (!ceiling)
+ return;
+ }
+ if (end - 1 > ceiling - 1)
+ return;
+
+ pmd = pmd_offset(pud, start);
+ pud_clear(pud);
+ pmd_free_tlb(tlb, pmd, start);
+ mm_dec_nr_pmds(tlb->mm);
+}
+
+static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
+ unsigned long addr, unsigned long end,
+ unsigned long floor, unsigned long ceiling)
+{
+ pud_t *pud;
+ unsigned long next;
+ unsigned long start;
+
+ start = addr;
+ pud = pud_offset(p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ free_pmd_range(tlb, pud, addr, next, floor, ceiling);
+ } while (pud++, addr = next, addr != end);
+
+ start &= P4D_MASK;
+ if (start < floor)
+ return;
+ if (ceiling) {
+ ceiling &= P4D_MASK;
+ if (!ceiling)
+ return;
+ }
+ if (end - 1 > ceiling - 1)
+ return;
+
+ pud = pud_offset(p4d, start);
+ p4d_clear(p4d);
+ pud_free_tlb(tlb, pud, start);
+ mm_dec_nr_puds(tlb->mm);
+}
+
+static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
+ unsigned long addr, unsigned long end,
+ unsigned long floor, unsigned long ceiling)
+{
+ p4d_t *p4d;
+ unsigned long next;
+ unsigned long start;
+
+ start = addr;
+ p4d = p4d_offset(pgd, addr);
+ do {
+ next = p4d_addr_end(addr, end);
+ if (p4d_none_or_clear_bad(p4d))
+ continue;
+ free_pud_range(tlb, p4d, addr, next, floor, ceiling);
+ } while (p4d++, addr = next, addr != end);
+
+ start &= PGDIR_MASK;
+ if (start < floor)
+ return;
+ if (ceiling) {
+ ceiling &= PGDIR_MASK;
+ if (!ceiling)
+ return;
+ }
+ if (end - 1 > ceiling - 1)
+ return;
+
+ p4d = p4d_offset(pgd, start);
+ pgd_clear(pgd);
+ p4d_free_tlb(tlb, p4d, start);
+}
+
+/*
+ * This function frees user-level page tables of a process.
+ */
+void free_pgd_range(struct mmu_gather *tlb,
+ unsigned long addr, unsigned long end,
+ unsigned long floor, unsigned long ceiling)
+{
+ pgd_t *pgd;
+ unsigned long next;
+
+ /*
+ * The next few lines have given us lots of grief...
+ *
+ * Why are we testing PMD* at this top level? Because often
+ * there will be no work to do at all, and we'd prefer not to
+ * go all the way down to the bottom just to discover that.
+ *
+ * Why all these "- 1"s? Because 0 represents both the bottom
+ * of the address space and the top of it (using -1 for the
+ * top wouldn't help much: the masks would do the wrong thing).
+ * The rule is that addr 0 and floor 0 refer to the bottom of
+ * the address space, but end 0 and ceiling 0 refer to the top
+ * Comparisons need to use "end - 1" and "ceiling - 1" (though
+ * that end 0 case should be mythical).
+ *
+ * Wherever addr is brought up or ceiling brought down, we must
+ * be careful to reject "the opposite 0" before it confuses the
+ * subsequent tests. But what about where end is brought down
+ * by PMD_SIZE below? no, end can't go down to 0 there.
+ *
+ * Whereas we round start (addr) and ceiling down, by different
+ * masks at different levels, in order to test whether a table
+ * now has no other vmas using it, so can be freed, we don't
+ * bother to round floor or end up - the tests don't need that.
+ */
+
+ addr &= PMD_MASK;
+ if (addr < floor) {
+ addr += PMD_SIZE;
+ if (!addr)
+ return;
+ }
+ if (ceiling) {
+ ceiling &= PMD_MASK;
+ if (!ceiling)
+ return;
+ }
+ if (end - 1 > ceiling - 1)
+ end -= PMD_SIZE;
+ if (addr > end - 1)
+ return;
+ /*
+ * We add page table cache pages with PAGE_SIZE,
+ * (see pte_free_tlb()), flush the tlb if we need
+ */
+ tlb_change_page_size(tlb, PAGE_SIZE);
+ pgd = pgd_offset(tlb->mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
+ } while (pgd++, addr = next, addr != end);
+}
+
+void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,
+ struct vm_area_struct *vma, unsigned long floor,
+ unsigned long ceiling)
+{
+ MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
+
+ do {
+ unsigned long addr = vma->vm_start;
+ struct vm_area_struct *next;
+
+ /*
+ * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
+ * be 0. This will underflow and is okay.
+ */
+ next = mas_find(&mas, ceiling - 1);
+
+ /*
+ * Hide vma from rmap and truncate_pagecache before freeing
+ * pgtables
+ */
+ unlink_anon_vmas(vma);
+ unlink_file_vma(vma);
+
+ if (is_vm_hugetlb_page(vma)) {
+ hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
+ floor, next ? next->vm_start : ceiling);
+ } else {
+ /*
+ * Optimization: gather nearby vmas into one call down
+ */
+ while (next && next->vm_start <= vma->vm_end + PMD_SIZE
+ && !is_vm_hugetlb_page(next)) {
+ vma = next;
+ next = mas_find(&mas, ceiling - 1);
+ unlink_anon_vmas(vma);
+ unlink_file_vma(vma);
+ }
+ free_pgd_range(tlb, addr, vma->vm_end,
+ floor, next ? next->vm_start : ceiling);
+ }
+ vma = next;
+ } while (vma);
+}
+
+void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
+{
+ spinlock_t *ptl = pmd_lock(mm, pmd);
+
+ if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
+ mm_inc_nr_ptes(mm);
+ /*
+ * Ensure all pte setup (eg. pte page lock and page clearing) are
+ * visible before the pte is made visible to other CPUs by being
+ * put into page tables.
+ *
+ * The other side of the story is the pointer chasing in the page
+ * table walking code (when walking the page table without locking;
+ * ie. most of the time). Fortunately, these data accesses consist
+ * of a chain of data-dependent loads, meaning most CPUs (alpha
+ * being the notable exception) will already guarantee loads are
+ * seen in-order. See the alpha page table accessors for the
+ * smp_rmb() barriers in page table walking code.
+ */
+ smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
+ pmd_populate(mm, pmd, *pte);
+ *pte = NULL;
+ }
+ spin_unlock(ptl);
+}
+
+int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
+{
+ pgtable_t new = pte_alloc_one(mm);
+ if (!new)
+ return -ENOMEM;
+
+ pmd_install(mm, pmd, &new);
+ if (new)
+ pte_free(mm, new);
+ return 0;
+}
+
+int __pte_alloc_kernel(pmd_t *pmd)
+{
+ pte_t *new = pte_alloc_one_kernel(&init_mm);
+ if (!new)
+ return -ENOMEM;
+
+ spin_lock(&init_mm.page_table_lock);
+ if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
+ smp_wmb(); /* See comment in pmd_install() */
+ pmd_populate_kernel(&init_mm, pmd, new);
+ new = NULL;
+ }
+ spin_unlock(&init_mm.page_table_lock);
+ if (new)
+ pte_free_kernel(&init_mm, new);
+ return 0;
+}
+
+static inline void init_rss_vec(int *rss)
+{
+ memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
+}
+
+static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
+{
+ int i;
+
+ if (current->mm == mm)
+ sync_mm_rss(mm);
+ for (i = 0; i < NR_MM_COUNTERS; i++)
+ if (rss[i])
+ add_mm_counter(mm, i, rss[i]);
+}
+
+/*
+ * This function is called to print an error when a bad pte
+ * is found. For example, we might have a PFN-mapped pte in
+ * a region that doesn't allow it.
+ *
+ * The calling function must still handle the error.
+ */
+static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte, struct page *page)
+{
+ pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
+ p4d_t *p4d = p4d_offset(pgd, addr);
+ pud_t *pud = pud_offset(p4d, addr);
+ pmd_t *pmd = pmd_offset(pud, addr);
+ struct address_space *mapping;
+ pgoff_t index;
+ static unsigned long resume;
+ static unsigned long nr_shown;
+ static unsigned long nr_unshown;
+
+ /*
+ * Allow a burst of 60 reports, then keep quiet for that minute;
+ * or allow a steady drip of one report per second.
+ */
+ if (nr_shown == 60) {
+ if (time_before(jiffies, resume)) {
+ nr_unshown++;
+ return;
+ }
+ if (nr_unshown) {
+ pr_alert("BUG: Bad page map: %lu messages suppressed\n",
+ nr_unshown);
+ nr_unshown = 0;
+ }
+ nr_shown = 0;
+ }
+ if (nr_shown++ == 0)
+ resume = jiffies + 60 * HZ;
+
+ mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
+ index = linear_page_index(vma, addr);
+
+ pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
+ current->comm,
+ (long long)pte_val(pte), (long long)pmd_val(*pmd));
+ if (page)
+ dump_page(page, "bad pte");
+ pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
+ (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
+ pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
+ vma->vm_file,
+ vma->vm_ops ? vma->vm_ops->fault : NULL,
+ vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
+ mapping ? mapping->a_ops->read_folio : NULL);
+ dump_stack();
+ add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+}
+
+/*
+ * vm_normal_page -- This function gets the "struct page" associated with a pte.
+ *
+ * "Special" mappings do not wish to be associated with a "struct page" (either
+ * it doesn't exist, or it exists but they don't want to touch it). In this
+ * case, NULL is returned here. "Normal" mappings do have a struct page.
+ *
+ * There are 2 broad cases. Firstly, an architecture may define a pte_special()
+ * pte bit, in which case this function is trivial. Secondly, an architecture
+ * may not have a spare pte bit, which requires a more complicated scheme,
+ * described below.
+ *
+ * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
+ * special mapping (even if there are underlying and valid "struct pages").
+ * COWed pages of a VM_PFNMAP are always normal.
+ *
+ * The way we recognize COWed pages within VM_PFNMAP mappings is through the
+ * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
+ * set, and the vm_pgoff will point to the first PFN mapped: thus every special
+ * mapping will always honor the rule
+ *
+ * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
+ *
+ * And for normal mappings this is false.
+ *
+ * This restricts such mappings to be a linear translation from virtual address
+ * to pfn. To get around this restriction, we allow arbitrary mappings so long
+ * as the vma is not a COW mapping; in that case, we know that all ptes are
+ * special (because none can have been COWed).
+ *
+ *
+ * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
+ *
+ * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
+ * page" backing, however the difference is that _all_ pages with a struct
+ * page (that is, those where pfn_valid is true) are refcounted and considered
+ * normal pages by the VM. The disadvantage is that pages are refcounted
+ * (which can be slower and simply not an option for some PFNMAP users). The
+ * advantage is that we don't have to follow the strict linearity rule of
+ * PFNMAP mappings in order to support COWable mappings.
+ *
+ */
+struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte)
+{
+ unsigned long pfn = pte_pfn(pte);
+
+ if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
+ if (likely(!pte_special(pte)))
+ goto check_pfn;
+ if (vma->vm_ops && vma->vm_ops->find_special_page)
+ return vma->vm_ops->find_special_page(vma, addr);
+ if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
+ return NULL;
+ if (is_zero_pfn(pfn))
+ return NULL;
+ if (pte_devmap(pte))
+ /*
+ * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
+ * and will have refcounts incremented on their struct pages
+ * when they are inserted into PTEs, thus they are safe to
+ * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
+ * do not have refcounts. Example of legacy ZONE_DEVICE is
+ * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
+ */
+ return NULL;
+
+ print_bad_pte(vma, addr, pte, NULL);
+ return NULL;
+ }
+
+ /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
+
+ if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
+ if (vma->vm_flags & VM_MIXEDMAP) {
+ if (!pfn_valid(pfn))
+ return NULL;
+ goto out;
+ } else {
+ unsigned long off;
+ off = (addr - vma->vm_start) >> PAGE_SHIFT;
+ if (pfn == vma->vm_pgoff + off)
+ return NULL;
+ if (!is_cow_mapping(vma->vm_flags))
+ return NULL;
+ }
+ }
+
+ if (is_zero_pfn(pfn))
+ return NULL;
+
+check_pfn:
+ if (unlikely(pfn > highest_memmap_pfn)) {
+ print_bad_pte(vma, addr, pte, NULL);
+ return NULL;
+ }
+
+ /*
+ * NOTE! We still have PageReserved() pages in the page tables.
+ * eg. VDSO mappings can cause them to exist.
+ */
+out:
+ return pfn_to_page(pfn);
+}
+
+struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte)
+{
+ struct page *page = vm_normal_page(vma, addr, pte);
+
+ if (page)
+ return page_folio(page);
+ return NULL;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t pmd)
+{
+ unsigned long pfn = pmd_pfn(pmd);
+
+ /*
+ * There is no pmd_special() but there may be special pmds, e.g.
+ * in a direct-access (dax) mapping, so let's just replicate the
+ * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here.
+ */
+ if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
+ if (vma->vm_flags & VM_MIXEDMAP) {
+ if (!pfn_valid(pfn))
+ return NULL;
+ goto out;
+ } else {
+ unsigned long off;
+ off = (addr - vma->vm_start) >> PAGE_SHIFT;
+ if (pfn == vma->vm_pgoff + off)
+ return NULL;
+ if (!is_cow_mapping(vma->vm_flags))
+ return NULL;
+ }
+ }
+
+ if (pmd_devmap(pmd))
+ return NULL;
+ if (is_huge_zero_pmd(pmd))
+ return NULL;
+ if (unlikely(pfn > highest_memmap_pfn))
+ return NULL;
+
+ /*
+ * NOTE! We still have PageReserved() pages in the page tables.
+ * eg. VDSO mappings can cause them to exist.
+ */
+out:
+ return pfn_to_page(pfn);
+}
+#endif
+
+static void restore_exclusive_pte(struct vm_area_struct *vma,
+ struct page *page, unsigned long address,
+ pte_t *ptep)
+{
+ pte_t pte;
+ swp_entry_t entry;
+
+ pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
+ if (pte_swp_soft_dirty(*ptep))
+ pte = pte_mksoft_dirty(pte);
+
+ entry = pte_to_swp_entry(*ptep);
+ if (pte_swp_uffd_wp(*ptep))
+ pte = pte_mkuffd_wp(pte);
+ else if (is_writable_device_exclusive_entry(entry))
+ pte = maybe_mkwrite(pte_mkdirty(pte), vma);
+
+ VM_BUG_ON(pte_write(pte) && !(PageAnon(page) && PageAnonExclusive(page)));
+
+ /*
+ * No need to take a page reference as one was already
+ * created when the swap entry was made.
+ */
+ if (PageAnon(page))
+ page_add_anon_rmap(page, vma, address, RMAP_NONE);
+ else
+ /*
+ * Currently device exclusive access only supports anonymous
+ * memory so the entry shouldn't point to a filebacked page.
+ */
+ WARN_ON_ONCE(1);
+
+ set_pte_at(vma->vm_mm, address, ptep, pte);
+
+ /*
+ * No need to invalidate - it was non-present before. However
+ * secondary CPUs may have mappings that need invalidating.
+ */
+ update_mmu_cache(vma, address, ptep);
+}
+
+/*
+ * Tries to restore an exclusive pte if the page lock can be acquired without
+ * sleeping.
+ */
+static int
+try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ swp_entry_t entry = pte_to_swp_entry(*src_pte);
+ struct page *page = pfn_swap_entry_to_page(entry);
+
+ if (trylock_page(page)) {
+ restore_exclusive_pte(vma, page, addr, src_pte);
+ unlock_page(page);
+ return 0;
+ }
+
+ return -EBUSY;
+}
+
+/*
+ * copy one vm_area from one task to the other. Assumes the page tables
+ * already present in the new task to be cleared in the whole range
+ * covered by this vma.
+ */
+
+static unsigned long
+copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+ pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
+ struct vm_area_struct *src_vma, unsigned long addr, int *rss)
+{
+ unsigned long vm_flags = dst_vma->vm_flags;
+ pte_t pte = *src_pte;
+ struct page *page;
+ swp_entry_t entry = pte_to_swp_entry(pte);
+
+ if (likely(!non_swap_entry(entry))) {
+ if (swap_duplicate(entry) < 0)
+ return -EIO;
+
+ /* make sure dst_mm is on swapoff's mmlist. */
+ if (unlikely(list_empty(&dst_mm->mmlist))) {
+ spin_lock(&mmlist_lock);
+ if (list_empty(&dst_mm->mmlist))
+ list_add(&dst_mm->mmlist,
+ &src_mm->mmlist);
+ spin_unlock(&mmlist_lock);
+ }
+ /* Mark the swap entry as shared. */
+ if (pte_swp_exclusive(*src_pte)) {
+ pte = pte_swp_clear_exclusive(*src_pte);
+ set_pte_at(src_mm, addr, src_pte, pte);
+ }
+ rss[MM_SWAPENTS]++;
+ } else if (is_migration_entry(entry)) {
+ page = pfn_swap_entry_to_page(entry);
+
+ rss[mm_counter(page)]++;
+
+ if (!is_readable_migration_entry(entry) &&
+ is_cow_mapping(vm_flags)) {
+ /*
+ * COW mappings require pages in both parent and child
+ * to be set to read. A previously exclusive entry is
+ * now shared.
+ */
+ entry = make_readable_migration_entry(
+ swp_offset(entry));
+ pte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(*src_pte))
+ pte = pte_swp_mksoft_dirty(pte);
+ if (pte_swp_uffd_wp(*src_pte))
+ pte = pte_swp_mkuffd_wp(pte);
+ set_pte_at(src_mm, addr, src_pte, pte);
+ }
+ } else if (is_device_private_entry(entry)) {
+ page = pfn_swap_entry_to_page(entry);
+
+ /*
+ * Update rss count even for unaddressable pages, as
+ * they should treated just like normal pages in this
+ * respect.
+ *
+ * We will likely want to have some new rss counters
+ * for unaddressable pages, at some point. But for now
+ * keep things as they are.
+ */
+ get_page(page);
+ rss[mm_counter(page)]++;
+ /* Cannot fail as these pages cannot get pinned. */
+ BUG_ON(page_try_dup_anon_rmap(page, false, src_vma));
+
+ /*
+ * We do not preserve soft-dirty information, because so
+ * far, checkpoint/restore is the only feature that
+ * requires that. And checkpoint/restore does not work
+ * when a device driver is involved (you cannot easily
+ * save and restore device driver state).
+ */
+ if (is_writable_device_private_entry(entry) &&
+ is_cow_mapping(vm_flags)) {
+ entry = make_readable_device_private_entry(
+ swp_offset(entry));
+ pte = swp_entry_to_pte(entry);
+ if (pte_swp_uffd_wp(*src_pte))
+ pte = pte_swp_mkuffd_wp(pte);
+ set_pte_at(src_mm, addr, src_pte, pte);
+ }
+ } else if (is_device_exclusive_entry(entry)) {
+ /*
+ * Make device exclusive entries present by restoring the
+ * original entry then copying as for a present pte. Device
+ * exclusive entries currently only support private writable
+ * (ie. COW) mappings.
+ */
+ VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
+ if (try_restore_exclusive_pte(src_pte, src_vma, addr))
+ return -EBUSY;
+ return -ENOENT;
+ } else if (is_pte_marker_entry(entry)) {
+ if (userfaultfd_wp(dst_vma))
+ set_pte_at(dst_mm, addr, dst_pte, pte);
+ return 0;
+ }
+ if (!userfaultfd_wp(dst_vma))
+ pte = pte_swp_clear_uffd_wp(pte);
+ set_pte_at(dst_mm, addr, dst_pte, pte);
+ return 0;
+}
+
+/*
+ * Copy a present and normal page.
+ *
+ * NOTE! The usual case is that this isn't required;
+ * instead, the caller can just increase the page refcount
+ * and re-use the pte the traditional way.
+ *
+ * And if we need a pre-allocated page but don't yet have
+ * one, return a negative error to let the preallocation
+ * code know so that it can do so outside the page table
+ * lock.
+ */
+static inline int
+copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
+ struct page **prealloc, struct page *page)
+{
+ struct page *new_page;
+ pte_t pte;
+
+ new_page = *prealloc;
+ if (!new_page)
+ return -EAGAIN;
+
+ /*
+ * We have a prealloc page, all good! Take it
+ * over and copy the page & arm it.
+ */
+ *prealloc = NULL;
+ copy_user_highpage(new_page, page, addr, src_vma);
+ __SetPageUptodate(new_page);
+ page_add_new_anon_rmap(new_page, dst_vma, addr);
+ lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
+ rss[mm_counter(new_page)]++;
+
+ /* All done, just insert the new page copy in the child */
+ pte = mk_pte(new_page, dst_vma->vm_page_prot);
+ pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
+ if (userfaultfd_pte_wp(dst_vma, *src_pte))
+ /* Uffd-wp needs to be delivered to dest pte as well */
+ pte = pte_wrprotect(pte_mkuffd_wp(pte));
+ set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
+ return 0;
+}
+
+/*
+ * Copy one pte. Returns 0 if succeeded, or -EAGAIN if one preallocated page
+ * is required to copy this pte.
+ */
+static inline int
+copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
+ struct page **prealloc)
+{
+ struct mm_struct *src_mm = src_vma->vm_mm;
+ unsigned long vm_flags = src_vma->vm_flags;
+ pte_t pte = *src_pte;
+ struct page *page;
+
+ page = vm_normal_page(src_vma, addr, pte);
+ if (page && PageAnon(page)) {
+ /*
+ * If this page may have been pinned by the parent process,
+ * copy the page immediately for the child so that we'll always
+ * guarantee the pinned page won't be randomly replaced in the
+ * future.
+ */
+ get_page(page);
+ if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) {
+ /* Page maybe pinned, we have to copy. */
+ put_page(page);
+ return copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
+ addr, rss, prealloc, page);
+ }
+ rss[mm_counter(page)]++;
+ } else if (page) {
+ get_page(page);
+ page_dup_file_rmap(page, false);
+ rss[mm_counter(page)]++;
+ }
+
+ /*
+ * If it's a COW mapping, write protect it both
+ * in the parent and the child
+ */
+ if (is_cow_mapping(vm_flags) && pte_write(pte)) {
+ ptep_set_wrprotect(src_mm, addr, src_pte);
+ pte = pte_wrprotect(pte);
+ }
+ VM_BUG_ON(page && PageAnon(page) && PageAnonExclusive(page));
+
+ /*
+ * If it's a shared mapping, mark it clean in
+ * the child
+ */
+ if (vm_flags & VM_SHARED)
+ pte = pte_mkclean(pte);
+ pte = pte_mkold(pte);
+
+ if (!userfaultfd_wp(dst_vma))
+ pte = pte_clear_uffd_wp(pte);
+
+ set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
+ return 0;
+}
+
+static inline struct page *
+page_copy_prealloc(struct mm_struct *src_mm, struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *new_page;
+
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, addr);
+ if (!new_page)
+ return NULL;
+
+ if (mem_cgroup_charge(page_folio(new_page), src_mm, GFP_KERNEL)) {
+ put_page(new_page);
+ return NULL;
+ }
+ cgroup_throttle_swaprate(new_page, GFP_KERNEL);
+
+ return new_page;
+}
+
+static int
+copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
+ unsigned long end)
+{
+ struct mm_struct *dst_mm = dst_vma->vm_mm;
+ struct mm_struct *src_mm = src_vma->vm_mm;
+ pte_t *orig_src_pte, *orig_dst_pte;
+ pte_t *src_pte, *dst_pte;
+ spinlock_t *src_ptl, *dst_ptl;
+ int progress, ret = 0;
+ int rss[NR_MM_COUNTERS];
+ swp_entry_t entry = (swp_entry_t){0};
+ struct page *prealloc = NULL;
+
+again:
+ progress = 0;
+ init_rss_vec(rss);
+
+ dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
+ if (!dst_pte) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ src_pte = pte_offset_map(src_pmd, addr);
+ src_ptl = pte_lockptr(src_mm, src_pmd);
+ spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+ orig_src_pte = src_pte;
+ orig_dst_pte = dst_pte;
+ arch_enter_lazy_mmu_mode();
+
+ do {
+ /*
+ * We are holding two locks at this point - either of them
+ * could generate latencies in another task on another CPU.
+ */
+ if (progress >= 32) {
+ progress = 0;
+ if (need_resched() ||
+ spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
+ break;
+ }
+ if (pte_none(*src_pte)) {
+ progress++;
+ continue;
+ }
+ if (unlikely(!pte_present(*src_pte))) {
+ ret = copy_nonpresent_pte(dst_mm, src_mm,
+ dst_pte, src_pte,
+ dst_vma, src_vma,
+ addr, rss);
+ if (ret == -EIO) {
+ entry = pte_to_swp_entry(*src_pte);
+ break;
+ } else if (ret == -EBUSY) {
+ break;
+ } else if (!ret) {
+ progress += 8;
+ continue;
+ }
+
+ /*
+ * Device exclusive entry restored, continue by copying
+ * the now present pte.
+ */
+ WARN_ON_ONCE(ret != -ENOENT);
+ }
+ /* copy_present_pte() will clear `*prealloc' if consumed */
+ ret = copy_present_pte(dst_vma, src_vma, dst_pte, src_pte,
+ addr, rss, &prealloc);
+ /*
+ * If we need a pre-allocated page for this pte, drop the
+ * locks, allocate, and try again.
+ */
+ if (unlikely(ret == -EAGAIN))
+ break;
+ if (unlikely(prealloc)) {
+ /*
+ * pre-alloc page cannot be reused by next time so as
+ * to strictly follow mempolicy (e.g., alloc_page_vma()
+ * will allocate page according to address). This
+ * could only happen if one pinned pte changed.
+ */
+ put_page(prealloc);
+ prealloc = NULL;
+ }
+ progress += 8;
+ } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
+
+ arch_leave_lazy_mmu_mode();
+ spin_unlock(src_ptl);
+ pte_unmap(orig_src_pte);
+ add_mm_rss_vec(dst_mm, rss);
+ pte_unmap_unlock(orig_dst_pte, dst_ptl);
+ cond_resched();
+
+ if (ret == -EIO) {
+ VM_WARN_ON_ONCE(!entry.val);
+ if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ entry.val = 0;
+ } else if (ret == -EBUSY) {
+ goto out;
+ } else if (ret == -EAGAIN) {
+ prealloc = page_copy_prealloc(src_mm, src_vma, addr);
+ if (!prealloc)
+ return -ENOMEM;
+ } else if (ret) {
+ VM_WARN_ON_ONCE(1);
+ }
+
+ /* We've captured and resolved the error. Reset, try again. */
+ ret = 0;
+
+ if (addr != end)
+ goto again;
+out:
+ if (unlikely(prealloc))
+ put_page(prealloc);
+ return ret;
+}
+
+static inline int
+copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
+ unsigned long end)
+{
+ struct mm_struct *dst_mm = dst_vma->vm_mm;
+ struct mm_struct *src_mm = src_vma->vm_mm;
+ pmd_t *src_pmd, *dst_pmd;
+ unsigned long next;
+
+ dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
+ if (!dst_pmd)
+ return -ENOMEM;
+ src_pmd = pmd_offset(src_pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
+ || pmd_devmap(*src_pmd)) {
+ int err;
+ VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
+ err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
+ addr, dst_vma, src_vma);
+ if (err == -ENOMEM)
+ return -ENOMEM;
+ if (!err)
+ continue;
+ /* fall through */
+ }
+ if (pmd_none_or_clear_bad(src_pmd))
+ continue;
+ if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
+ addr, next))
+ return -ENOMEM;
+ } while (dst_pmd++, src_pmd++, addr = next, addr != end);
+ return 0;
+}
+
+static inline int
+copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
+ unsigned long end)
+{
+ struct mm_struct *dst_mm = dst_vma->vm_mm;
+ struct mm_struct *src_mm = src_vma->vm_mm;
+ pud_t *src_pud, *dst_pud;
+ unsigned long next;
+
+ dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
+ if (!dst_pud)
+ return -ENOMEM;
+ src_pud = pud_offset(src_p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
+ int err;
+
+ VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
+ err = copy_huge_pud(dst_mm, src_mm,
+ dst_pud, src_pud, addr, src_vma);
+ if (err == -ENOMEM)
+ return -ENOMEM;
+ if (!err)
+ continue;
+ /* fall through */
+ }
+ if (pud_none_or_clear_bad(src_pud))
+ continue;
+ if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
+ addr, next))
+ return -ENOMEM;
+ } while (dst_pud++, src_pud++, addr = next, addr != end);
+ return 0;
+}
+
+static inline int
+copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
+ pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
+ unsigned long end)
+{
+ struct mm_struct *dst_mm = dst_vma->vm_mm;
+ p4d_t *src_p4d, *dst_p4d;
+ unsigned long next;
+
+ dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
+ if (!dst_p4d)
+ return -ENOMEM;
+ src_p4d = p4d_offset(src_pgd, addr);
+ do {
+ next = p4d_addr_end(addr, end);
+ if (p4d_none_or_clear_bad(src_p4d))
+ continue;
+ if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
+ addr, next))
+ return -ENOMEM;
+ } while (dst_p4d++, src_p4d++, addr = next, addr != end);
+ return 0;
+}
+
+/*
+ * Return true if the vma needs to copy the pgtable during this fork(). Return
+ * false when we can speed up fork() by allowing lazy page faults later until
+ * when the child accesses the memory range.
+ */
+static bool
+vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
+{
+ /*
+ * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
+ * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
+ * contains uffd-wp protection information, that's something we can't
+ * retrieve from page cache, and skip copying will lose those info.
+ */
+ if (userfaultfd_wp(dst_vma))
+ return true;
+
+ if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
+ return true;
+
+ if (src_vma->anon_vma)
+ return true;
+
+ /*
+ * Don't copy ptes where a page fault will fill them correctly. Fork
+ * becomes much lighter when there are big shared or private readonly
+ * mappings. The tradeoff is that copy_page_range is more efficient
+ * than faulting.
+ */
+ return false;
+}
+
+int
+copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
+{
+ pgd_t *src_pgd, *dst_pgd;
+ unsigned long next;
+ unsigned long addr = src_vma->vm_start;
+ unsigned long end = src_vma->vm_end;
+ struct mm_struct *dst_mm = dst_vma->vm_mm;
+ struct mm_struct *src_mm = src_vma->vm_mm;
+ struct mmu_notifier_range range;
+ bool is_cow;
+ int ret;
+
+ if (!vma_needs_copy(dst_vma, src_vma))
+ return 0;
+
+ if (is_vm_hugetlb_page(src_vma))
+ return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
+
+ if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
+ /*
+ * We do not free on error cases below as remove_vma
+ * gets called on error from higher level routine
+ */
+ ret = track_pfn_copy(src_vma);
+ if (ret)
+ return ret;
+ }
+
+ /*
+ * We need to invalidate the secondary MMU mappings only when
+ * there could be a permission downgrade on the ptes of the
+ * parent mm. And a permission downgrade will only happen if
+ * is_cow_mapping() returns true.
+ */
+ is_cow = is_cow_mapping(src_vma->vm_flags);
+
+ if (is_cow) {
+ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
+ 0, src_vma, src_mm, addr, end);
+ mmu_notifier_invalidate_range_start(&range);
+ /*
+ * Disabling preemption is not needed for the write side, as
+ * the read side doesn't spin, but goes to the mmap_lock.
+ *
+ * Use the raw variant of the seqcount_t write API to avoid
+ * lockdep complaining about preemptibility.
+ */
+ mmap_assert_write_locked(src_mm);
+ raw_write_seqcount_begin(&src_mm->write_protect_seq);
+ }
+
+ ret = 0;
+ dst_pgd = pgd_offset(dst_mm, addr);
+ src_pgd = pgd_offset(src_mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(src_pgd))
+ continue;
+ if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
+ addr, next))) {
+ ret = -ENOMEM;
+ break;
+ }
+ } while (dst_pgd++, src_pgd++, addr = next, addr != end);
+
+ if (is_cow) {
+ raw_write_seqcount_end(&src_mm->write_protect_seq);
+ mmu_notifier_invalidate_range_end(&range);
+ }
+ return ret;
+}
+
+/* Whether we should zap all COWed (private) pages too */
+static inline bool should_zap_cows(struct zap_details *details)
+{
+ /* By default, zap all pages */
+ if (!details)
+ return true;
+
+ /* Or, we zap COWed pages only if the caller wants to */
+ return details->even_cows;
+}
+
+/* Decides whether we should zap this page with the page pointer specified */
+static inline bool should_zap_page(struct zap_details *details, struct page *page)
+{
+ /* If we can make a decision without *page.. */
+ if (should_zap_cows(details))
+ return true;
+
+ /* E.g. the caller passes NULL for the case of a zero page */
+ if (!page)
+ return true;
+
+ /* Otherwise we should only zap non-anon pages */
+ return !PageAnon(page);
+}
+
+static inline bool zap_drop_file_uffd_wp(struct zap_details *details)
+{
+ if (!details)
+ return false;
+
+ return details->zap_flags & ZAP_FLAG_DROP_MARKER;
+}
+
+/*
+ * This function makes sure that we'll replace the none pte with an uffd-wp
+ * swap special pte marker when necessary. Must be with the pgtable lock held.
+ */
+static inline void
+zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *pte,
+ struct zap_details *details, pte_t pteval)
+{
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
+ if (zap_drop_file_uffd_wp(details))
+ return;
+
+ pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
+#endif
+}
+
+static unsigned long zap_pte_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
+{
+ struct mm_struct *mm = tlb->mm;
+ int force_flush = 0;
+ int rss[NR_MM_COUNTERS];
+ spinlock_t *ptl;
+ pte_t *start_pte;
+ pte_t *pte;
+ swp_entry_t entry;
+
+ tlb_change_page_size(tlb, PAGE_SIZE);
+again:
+ init_rss_vec(rss);
+ start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ pte = start_pte;
+ flush_tlb_batched_pending(mm);
+ arch_enter_lazy_mmu_mode();
+ do {
+ pte_t ptent = *pte;
+ struct page *page;
+
+ if (pte_none(ptent))
+ continue;
+
+ if (need_resched())
+ break;
+
+ if (pte_present(ptent)) {
+ page = vm_normal_page(vma, addr, ptent);
+ if (unlikely(!should_zap_page(details, page)))
+ continue;
+ ptent = ptep_get_and_clear_full(mm, addr, pte,
+ tlb->fullmm);
+ tlb_remove_tlb_entry(tlb, pte, addr);
+ zap_install_uffd_wp_if_needed(vma, addr, pte, details,
+ ptent);
+ if (unlikely(!page))
+ continue;
+
+ if (!PageAnon(page)) {
+ if (pte_dirty(ptent)) {
+ force_flush = 1;
+ set_page_dirty(page);
+ }
+ if (pte_young(ptent) &&
+ likely(!(vma->vm_flags & VM_SEQ_READ)))
+ mark_page_accessed(page);
+ }
+ rss[mm_counter(page)]--;
+ page_remove_rmap(page, vma, false);
+ if (unlikely(page_mapcount(page) < 0))
+ print_bad_pte(vma, addr, ptent, page);
+ if (unlikely(__tlb_remove_page(tlb, page))) {
+ force_flush = 1;
+ addr += PAGE_SIZE;
+ break;
+ }
+ continue;
+ }
+
+ entry = pte_to_swp_entry(ptent);
+ if (is_device_private_entry(entry) ||
+ is_device_exclusive_entry(entry)) {
+ page = pfn_swap_entry_to_page(entry);
+ if (unlikely(!should_zap_page(details, page)))
+ continue;
+ /*
+ * Both device private/exclusive mappings should only
+ * work with anonymous page so far, so we don't need to
+ * consider uffd-wp bit when zap. For more information,
+ * see zap_install_uffd_wp_if_needed().
+ */
+ WARN_ON_ONCE(!vma_is_anonymous(vma));
+ rss[mm_counter(page)]--;
+ if (is_device_private_entry(entry))
+ page_remove_rmap(page, vma, false);
+ put_page(page);
+ } else if (!non_swap_entry(entry)) {
+ /* Genuine swap entry, hence a private anon page */
+ if (!should_zap_cows(details))
+ continue;
+ rss[MM_SWAPENTS]--;
+ if (unlikely(!free_swap_and_cache(entry)))
+ print_bad_pte(vma, addr, ptent, NULL);
+ } else if (is_migration_entry(entry)) {
+ page = pfn_swap_entry_to_page(entry);
+ if (!should_zap_page(details, page))
+ continue;
+ rss[mm_counter(page)]--;
+ } else if (pte_marker_entry_uffd_wp(entry)) {
+ /* Only drop the uffd-wp marker if explicitly requested */
+ if (!zap_drop_file_uffd_wp(details))
+ continue;
+ } else if (is_hwpoison_entry(entry) ||
+ is_swapin_error_entry(entry)) {
+ if (!should_zap_cows(details))
+ continue;
+ } else {
+ /* We should have covered all the swap entry types */
+ WARN_ON_ONCE(1);
+ }
+ pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+ zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+
+ add_mm_rss_vec(mm, rss);
+ arch_leave_lazy_mmu_mode();
+
+ /* Do the actual TLB flush before dropping ptl */
+ if (force_flush)
+ tlb_flush_mmu_tlbonly(tlb);
+ pte_unmap_unlock(start_pte, ptl);
+
+ /*
+ * If we forced a TLB flush (either due to running out of
+ * batch buffers or because we needed to flush dirty TLB
+ * entries before releasing the ptl), free the batched
+ * memory too. Restart if we didn't do everything.
+ */
+ if (force_flush) {
+ force_flush = 0;
+ tlb_flush_mmu(tlb);
+ }
+
+ if (addr != end) {
+ cond_resched();
+ goto again;
+ }
+
+ return addr;
+}
+
+static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, pud_t *pud,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
+{
+ pmd_t *pmd;
+ unsigned long next;
+
+ pmd = pmd_offset(pud, addr);
+ do {
+ next = pmd_addr_end(addr, end);
+ if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
+ if (next - addr != HPAGE_PMD_SIZE)
+ __split_huge_pmd(vma, pmd, addr, false, NULL);
+ else if (zap_huge_pmd(tlb, vma, pmd, addr))
+ goto next;
+ /* fall through */
+ } else if (details && details->single_folio &&
+ folio_test_pmd_mappable(details->single_folio) &&
+ next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
+ spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
+ /*
+ * Take and drop THP pmd lock so that we cannot return
+ * prematurely, while zap_huge_pmd() has cleared *pmd,
+ * but not yet decremented compound_mapcount().
+ */
+ spin_unlock(ptl);
+ }
+
+ /*
+ * Here there can be other concurrent MADV_DONTNEED or
+ * trans huge page faults running, and if the pmd is
+ * none or trans huge it can change under us. This is
+ * because MADV_DONTNEED holds the mmap_lock in read
+ * mode.
+ */
+ if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+ goto next;
+ next = zap_pte_range(tlb, vma, pmd, addr, next, details);
+next:
+ cond_resched();
+ } while (pmd++, addr = next, addr != end);
+
+ return addr;
+}
+
+static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, p4d_t *p4d,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
+{
+ pud_t *pud;
+ unsigned long next;
+
+ pud = pud_offset(p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
+ if (next - addr != HPAGE_PUD_SIZE) {
+ mmap_assert_locked(tlb->mm);
+ split_huge_pud(vma, pud, addr);
+ } else if (zap_huge_pud(tlb, vma, pud, addr))
+ goto next;
+ /* fall through */
+ }
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ next = zap_pmd_range(tlb, vma, pud, addr, next, details);
+next:
+ cond_resched();
+ } while (pud++, addr = next, addr != end);
+
+ return addr;
+}
+
+static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, pgd_t *pgd,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
+{
+ p4d_t *p4d;
+ unsigned long next;
+
+ p4d = p4d_offset(pgd, addr);
+ do {
+ next = p4d_addr_end(addr, end);
+ if (p4d_none_or_clear_bad(p4d))
+ continue;
+ next = zap_pud_range(tlb, vma, p4d, addr, next, details);
+ } while (p4d++, addr = next, addr != end);
+
+ return addr;
+}
+
+void unmap_page_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end,
+ struct zap_details *details)
+{
+ pgd_t *pgd;
+ unsigned long next;
+
+ BUG_ON(addr >= end);
+ tlb_start_vma(tlb, vma);
+ pgd = pgd_offset(vma->vm_mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
+ } while (pgd++, addr = next, addr != end);
+ tlb_end_vma(tlb, vma);
+}
+
+
+static void unmap_single_vma(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, unsigned long start_addr,
+ unsigned long end_addr,
+ struct zap_details *details)
+{
+ unsigned long start = max(vma->vm_start, start_addr);
+ unsigned long end;
+
+ if (start >= vma->vm_end)
+ return;
+ end = min(vma->vm_end, end_addr);
+ if (end <= vma->vm_start)
+ return;
+
+ if (vma->vm_file)
+ uprobe_munmap(vma, start, end);
+
+ if (unlikely(vma->vm_flags & VM_PFNMAP))
+ untrack_pfn(vma, 0, 0);
+
+ if (start != end) {
+ if (unlikely(is_vm_hugetlb_page(vma))) {
+ /*
+ * It is undesirable to test vma->vm_file as it
+ * should be non-null for valid hugetlb area.
+ * However, vm_file will be NULL in the error
+ * cleanup path of mmap_region. When
+ * hugetlbfs ->mmap method fails,
+ * mmap_region() nullifies vma->vm_file
+ * before calling this function to clean up.
+ * Since no pte has actually been setup, it is
+ * safe to do nothing in this case.
+ */
+ if (vma->vm_file) {
+ zap_flags_t zap_flags = details ?
+ details->zap_flags : 0;
+ __unmap_hugepage_range_final(tlb, vma, start, end,
+ NULL, zap_flags);
+ }
+ } else
+ unmap_page_range(tlb, vma, start, end, details);
+ }
+}
+
+/**
+ * unmap_vmas - unmap a range of memory covered by a list of vma's
+ * @tlb: address of the caller's struct mmu_gather
+ * @mt: the maple tree
+ * @vma: the starting vma
+ * @start_addr: virtual address at which to start unmapping
+ * @end_addr: virtual address at which to end unmapping
+ *
+ * Unmap all pages in the vma list.
+ *
+ * Only addresses between `start' and `end' will be unmapped.
+ *
+ * The VMA list must be sorted in ascending virtual address order.
+ *
+ * unmap_vmas() assumes that the caller will flush the whole unmapped address
+ * range after unmap_vmas() returns. So the only responsibility here is to
+ * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
+ * drops the lock and schedules.
+ */
+void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
+ struct vm_area_struct *vma, unsigned long start_addr,
+ unsigned long end_addr)
+{
+ struct mmu_notifier_range range;
+ struct zap_details details = {
+ .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
+ /* Careful - we need to zap private pages too! */
+ .even_cows = true,
+ };
+ MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
+ start_addr, end_addr);
+ mmu_notifier_invalidate_range_start(&range);
+ do {
+ unmap_single_vma(tlb, vma, start_addr, end_addr, &details);
+ } while ((vma = mas_find(&mas, end_addr - 1)) != NULL);
+ mmu_notifier_invalidate_range_end(&range);
+}
+
+/**
+ * zap_page_range - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @start: starting address of pages to zap
+ * @size: number of bytes to zap
+ *
+ * Caller must protect the VMA list
+ */
+void zap_page_range(struct vm_area_struct *vma, unsigned long start,
+ unsigned long size)
+{
+ struct maple_tree *mt = &vma->vm_mm->mm_mt;
+ unsigned long end = start + size;
+ struct mmu_notifier_range range;
+ struct mmu_gather tlb;
+ MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
+
+ lru_add_drain();
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
+ start, start + size);
+ tlb_gather_mmu(&tlb, vma->vm_mm);
+ update_hiwater_rss(vma->vm_mm);
+ mmu_notifier_invalidate_range_start(&range);
+ do {
+ unmap_single_vma(&tlb, vma, start, range.end, NULL);
+ } while ((vma = mas_find(&mas, end - 1)) != NULL);
+ mmu_notifier_invalidate_range_end(&range);
+ tlb_finish_mmu(&tlb);
+}
+
+/**
+ * zap_page_range_single - remove user pages in a given range
+ * @vma: vm_area_struct holding the applicable pages
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ * @details: details of shared cache invalidation
+ *
+ * The range must fit into one VMA.
+ */
+void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
+ unsigned long size, struct zap_details *details)
+{
+ const unsigned long end = address + size;
+ struct mmu_notifier_range range;
+ struct mmu_gather tlb;
+
+ lru_add_drain();
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
+ address, end);
+ if (is_vm_hugetlb_page(vma))
+ adjust_range_if_pmd_sharing_possible(vma, &range.start,
+ &range.end);
+ tlb_gather_mmu(&tlb, vma->vm_mm);
+ update_hiwater_rss(vma->vm_mm);
+ mmu_notifier_invalidate_range_start(&range);
+ /*
+ * unmap 'address-end' not 'range.start-range.end' as range
+ * could have been expanded for hugetlb pmd sharing.
+ */
+ unmap_single_vma(&tlb, vma, address, end, details);
+ mmu_notifier_invalidate_range_end(&range);
+ tlb_finish_mmu(&tlb);
+}
+
+/**
+ * zap_vma_ptes - remove ptes mapping the vma
+ * @vma: vm_area_struct holding ptes to be zapped
+ * @address: starting address of pages to zap
+ * @size: number of bytes to zap
+ *
+ * This function only unmaps ptes assigned to VM_PFNMAP vmas.
+ *
+ * The entire address range must be fully contained within the vma.
+ *
+ */
+void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
+ unsigned long size)
+{
+ if (!range_in_vma(vma, address, address + size) ||
+ !(vma->vm_flags & VM_PFNMAP))
+ return;
+
+ zap_page_range_single(vma, address, size, NULL);
+}
+EXPORT_SYMBOL_GPL(zap_vma_ptes);
+
+static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ pgd = pgd_offset(mm, addr);
+ p4d = p4d_alloc(mm, pgd, addr);
+ if (!p4d)
+ return NULL;
+ pud = pud_alloc(mm, p4d, addr);
+ if (!pud)
+ return NULL;
+ pmd = pmd_alloc(mm, pud, addr);
+ if (!pmd)
+ return NULL;
+
+ VM_BUG_ON(pmd_trans_huge(*pmd));
+ return pmd;
+}
+
+pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
+ spinlock_t **ptl)
+{
+ pmd_t *pmd = walk_to_pmd(mm, addr);
+
+ if (!pmd)
+ return NULL;
+ return pte_alloc_map_lock(mm, pmd, addr, ptl);
+}
+
+static int validate_page_before_insert(struct page *page)
+{
+ if (PageAnon(page) || PageSlab(page) || page_has_type(page))
+ return -EINVAL;
+ flush_dcache_page(page);
+ return 0;
+}
+
+static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
+ unsigned long addr, struct page *page, pgprot_t prot)
+{
+ if (!pte_none(*pte))
+ return -EBUSY;
+ /* Ok, finally just insert the thing.. */
+ get_page(page);
+ inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
+ page_add_file_rmap(page, vma, false);
+ set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
+ return 0;
+}
+
+/*
+ * This is the old fallback for page remapping.
+ *
+ * For historical reasons, it only allows reserved pages. Only
+ * old drivers should use this, and they needed to mark their
+ * pages reserved for the old functions anyway.
+ */
+static int insert_page(struct vm_area_struct *vma, unsigned long addr,
+ struct page *page, pgprot_t prot)
+{
+ int retval;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ retval = validate_page_before_insert(page);
+ if (retval)
+ goto out;
+ retval = -ENOMEM;
+ pte = get_locked_pte(vma->vm_mm, addr, &ptl);
+ if (!pte)
+ goto out;
+ retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
+ pte_unmap_unlock(pte, ptl);
+out:
+ return retval;
+}
+
+#ifdef pte_index
+static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
+ unsigned long addr, struct page *page, pgprot_t prot)
+{
+ int err;
+
+ if (!page_count(page))
+ return -EINVAL;
+ err = validate_page_before_insert(page);
+ if (err)
+ return err;
+ return insert_page_into_pte_locked(vma, pte, addr, page, prot);
+}
+
+/* insert_pages() amortizes the cost of spinlock operations
+ * when inserting pages in a loop. Arch *must* define pte_index.
+ */
+static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
+ struct page **pages, unsigned long *num, pgprot_t prot)
+{
+ pmd_t *pmd = NULL;
+ pte_t *start_pte, *pte;
+ spinlock_t *pte_lock;
+ struct mm_struct *const mm = vma->vm_mm;
+ unsigned long curr_page_idx = 0;
+ unsigned long remaining_pages_total = *num;
+ unsigned long pages_to_write_in_pmd;
+ int ret;
+more:
+ ret = -EFAULT;
+ pmd = walk_to_pmd(mm, addr);
+ if (!pmd)
+ goto out;
+
+ pages_to_write_in_pmd = min_t(unsigned long,
+ remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
+
+ /* Allocate the PTE if necessary; takes PMD lock once only. */
+ ret = -ENOMEM;
+ if (pte_alloc(mm, pmd))
+ goto out;
+
+ while (pages_to_write_in_pmd) {
+ int pte_idx = 0;
+ const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
+
+ start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
+ for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
+ int err = insert_page_in_batch_locked(vma, pte,
+ addr, pages[curr_page_idx], prot);
+ if (unlikely(err)) {
+ pte_unmap_unlock(start_pte, pte_lock);
+ ret = err;
+ remaining_pages_total -= pte_idx;
+ goto out;
+ }
+ addr += PAGE_SIZE;
+ ++curr_page_idx;
+ }
+ pte_unmap_unlock(start_pte, pte_lock);
+ pages_to_write_in_pmd -= batch_size;
+ remaining_pages_total -= batch_size;
+ }
+ if (remaining_pages_total)
+ goto more;
+ ret = 0;
+out:
+ *num = remaining_pages_total;
+ return ret;
+}
+#endif /* ifdef pte_index */
+
+/**
+ * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
+ * @vma: user vma to map to
+ * @addr: target start user address of these pages
+ * @pages: source kernel pages
+ * @num: in: number of pages to map. out: number of pages that were *not*
+ * mapped. (0 means all pages were successfully mapped).
+ *
+ * Preferred over vm_insert_page() when inserting multiple pages.
+ *
+ * In case of error, we may have mapped a subset of the provided
+ * pages. It is the caller's responsibility to account for this case.
+ *
+ * The same restrictions apply as in vm_insert_page().
+ */
+int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
+ struct page **pages, unsigned long *num)
+{
+#ifdef pte_index
+ const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
+
+ if (addr < vma->vm_start || end_addr >= vma->vm_end)
+ return -EFAULT;
+ if (!(vma->vm_flags & VM_MIXEDMAP)) {
+ BUG_ON(mmap_read_trylock(vma->vm_mm));
+ BUG_ON(vma->vm_flags & VM_PFNMAP);
+ vma->vm_flags |= VM_MIXEDMAP;
+ }
+ /* Defer page refcount checking till we're about to map that page. */
+ return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
+#else
+ unsigned long idx = 0, pgcount = *num;
+ int err = -EINVAL;
+
+ for (; idx < pgcount; ++idx) {
+ err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
+ if (err)
+ break;
+ }
+ *num = pgcount - idx;
+ return err;
+#endif /* ifdef pte_index */
+}
+EXPORT_SYMBOL(vm_insert_pages);
+
+/**
+ * vm_insert_page - insert single page into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @page: source kernel page
+ *
+ * This allows drivers to insert individual pages they've allocated
+ * into a user vma.
+ *
+ * The page has to be a nice clean _individual_ kernel allocation.
+ * If you allocate a compound page, you need to have marked it as
+ * such (__GFP_COMP), or manually just split the page up yourself
+ * (see split_page()).
+ *
+ * NOTE! Traditionally this was done with "remap_pfn_range()" which
+ * took an arbitrary page protection parameter. This doesn't allow
+ * that. Your vma protection will have to be set up correctly, which
+ * means that if you want a shared writable mapping, you'd better
+ * ask for a shared writable mapping!
+ *
+ * The page does not need to be reserved.
+ *
+ * Usually this function is called from f_op->mmap() handler
+ * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
+ * Caller must set VM_MIXEDMAP on vma if it wants to call this
+ * function from other places, for example from page-fault handler.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
+ struct page *page)
+{
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return -EFAULT;
+ if (!page_count(page))
+ return -EINVAL;
+ if (!(vma->vm_flags & VM_MIXEDMAP)) {
+ BUG_ON(mmap_read_trylock(vma->vm_mm));
+ BUG_ON(vma->vm_flags & VM_PFNMAP);
+ vma->vm_flags |= VM_MIXEDMAP;
+ }
+ return insert_page(vma, addr, page, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_insert_page);
+
+/*
+ * __vm_map_pages - maps range of kernel pages into user vma
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ * @offset: user's requested vm_pgoff
+ *
+ * This allows drivers to map range of kernel pages into a user vma.
+ *
+ * Return: 0 on success and error code otherwise.
+ */
+static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
+ unsigned long num, unsigned long offset)
+{
+ unsigned long count = vma_pages(vma);
+ unsigned long uaddr = vma->vm_start;
+ int ret, i;
+
+ /* Fail if the user requested offset is beyond the end of the object */
+ if (offset >= num)
+ return -ENXIO;
+
+ /* Fail if the user requested size exceeds available object size */
+ if (count > num - offset)
+ return -ENXIO;
+
+ for (i = 0; i < count; i++) {
+ ret = vm_insert_page(vma, uaddr, pages[offset + i]);
+ if (ret < 0)
+ return ret;
+ uaddr += PAGE_SIZE;
+ }
+
+ return 0;
+}
+
+/**
+ * vm_map_pages - maps range of kernel pages starts with non zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Maps an object consisting of @num pages, catering for the user's
+ * requested vm_pgoff
+ *
+ * If we fail to insert any page into the vma, the function will return
+ * immediately leaving any previously inserted pages present. Callers
+ * from the mmap handler may immediately return the error as their caller
+ * will destroy the vma, removing any successfully inserted pages. Other
+ * callers should make their own arrangements for calling unmap_region().
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
+ unsigned long num)
+{
+ return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
+}
+EXPORT_SYMBOL(vm_map_pages);
+
+/**
+ * vm_map_pages_zero - map range of kernel pages starts with zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Similar to vm_map_pages(), except that it explicitly sets the offset
+ * to 0. This function is intended for the drivers that did not consider
+ * vm_pgoff.
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
+ unsigned long num)
+{
+ return __vm_map_pages(vma, pages, num, 0);
+}
+EXPORT_SYMBOL(vm_map_pages_zero);
+
+static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn, pgprot_t prot, bool mkwrite)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pte_t *pte, entry;
+ spinlock_t *ptl;
+
+ pte = get_locked_pte(mm, addr, &ptl);
+ if (!pte)
+ return VM_FAULT_OOM;
+ if (!pte_none(*pte)) {
+ if (mkwrite) {
+ /*
+ * For read faults on private mappings the PFN passed
+ * in may not match the PFN we have mapped if the
+ * mapped PFN is a writeable COW page. In the mkwrite
+ * case we are creating a writable PTE for a shared
+ * mapping and we expect the PFNs to match. If they
+ * don't match, we are likely racing with block
+ * allocation and mapping invalidation so just skip the
+ * update.
+ */
+ if (pte_pfn(*pte) != pfn_t_to_pfn(pfn)) {
+ WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte)));
+ goto out_unlock;
+ }
+ entry = pte_mkyoung(*pte);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (ptep_set_access_flags(vma, addr, pte, entry, 1))
+ update_mmu_cache(vma, addr, pte);
+ }
+ goto out_unlock;
+ }
+
+ /* Ok, finally just insert the thing.. */
+ if (pfn_t_devmap(pfn))
+ entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
+ else
+ entry = pte_mkspecial(pfn_t_pte(pfn, prot));
+
+ if (mkwrite) {
+ entry = pte_mkyoung(entry);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ }
+
+ set_pte_at(mm, addr, pte, entry);
+ update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
+
+out_unlock:
+ pte_unmap_unlock(pte, ptl);
+ return VM_FAULT_NOPAGE;
+}
+
+/**
+ * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ * @pgprot: pgprot flags for the inserted page
+ *
+ * This is exactly like vmf_insert_pfn(), except that it allows drivers
+ * to override pgprot on a per-page basis.
+ *
+ * This only makes sense for IO mappings, and it makes no sense for
+ * COW mappings. In general, using multiple vmas is preferable;
+ * vmf_insert_pfn_prot should only be used if using multiple VMAs is
+ * impractical.
+ *
+ * See vmf_insert_mixed_prot() for a discussion of the implication of using
+ * a value of @pgprot different from that of @vma->vm_page_prot.
+ *
+ * Context: Process context. May allocate using %GFP_KERNEL.
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, pgprot_t pgprot)
+{
+ /*
+ * Technically, architectures with pte_special can avoid all these
+ * restrictions (same for remap_pfn_range). However we would like
+ * consistency in testing and feature parity among all, so we should
+ * try to keep these invariants in place for everybody.
+ */
+ BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
+ BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+ (VM_PFNMAP|VM_MIXEDMAP));
+ BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+ BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return VM_FAULT_SIGBUS;
+
+ if (!pfn_modify_allowed(pfn, pgprot))
+ return VM_FAULT_SIGBUS;
+
+ track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
+
+ return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
+ false);
+}
+EXPORT_SYMBOL(vmf_insert_pfn_prot);
+
+/**
+ * vmf_insert_pfn - insert single pfn into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ *
+ * Similar to vm_insert_page, this allows drivers to insert individual pages
+ * they've allocated into a user vma. Same comments apply.
+ *
+ * This function should only be called from a vm_ops->fault handler, and
+ * in that case the handler should return the result of this function.
+ *
+ * vma cannot be a COW mapping.
+ *
+ * As this is called only for pages that do not currently exist, we
+ * do not need to flush old virtual caches or the TLB.
+ *
+ * Context: Process context. May allocate using %GFP_KERNEL.
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn)
+{
+ return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vmf_insert_pfn);
+
+static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
+{
+ /* these checks mirror the abort conditions in vm_normal_page */
+ if (vma->vm_flags & VM_MIXEDMAP)
+ return true;
+ if (pfn_t_devmap(pfn))
+ return true;
+ if (pfn_t_special(pfn))
+ return true;
+ if (is_zero_pfn(pfn_t_to_pfn(pfn)))
+ return true;
+ return false;
+}
+
+static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
+ unsigned long addr, pfn_t pfn, pgprot_t pgprot,
+ bool mkwrite)
+{
+ int err;
+
+ BUG_ON(!vm_mixed_ok(vma, pfn));
+
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return VM_FAULT_SIGBUS;
+
+ track_pfn_insert(vma, &pgprot, pfn);
+
+ if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * If we don't have pte special, then we have to use the pfn_valid()
+ * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
+ * refcount the page if pfn_valid is true (hence insert_page rather
+ * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
+ * without pte special, it would there be refcounted as a normal page.
+ */
+ if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
+ !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
+ struct page *page;
+
+ /*
+ * At this point we are committed to insert_page()
+ * regardless of whether the caller specified flags that
+ * result in pfn_t_has_page() == false.
+ */
+ page = pfn_to_page(pfn_t_to_pfn(pfn));
+ err = insert_page(vma, addr, page, pgprot);
+ } else {
+ return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
+ }
+
+ if (err == -ENOMEM)
+ return VM_FAULT_OOM;
+ if (err < 0 && err != -EBUSY)
+ return VM_FAULT_SIGBUS;
+
+ return VM_FAULT_NOPAGE;
+}
+
+/**
+ * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ * @pgprot: pgprot flags for the inserted page
+ *
+ * This is exactly like vmf_insert_mixed(), except that it allows drivers
+ * to override pgprot on a per-page basis.
+ *
+ * Typically this function should be used by drivers to set caching- and
+ * encryption bits different than those of @vma->vm_page_prot, because
+ * the caching- or encryption mode may not be known at mmap() time.
+ * This is ok as long as @vma->vm_page_prot is not used by the core vm
+ * to set caching and encryption bits for those vmas (except for COW pages).
+ * This is ensured by core vm only modifying these page table entries using
+ * functions that don't touch caching- or encryption bits, using pte_modify()
+ * if needed. (See for example mprotect()).
+ * Also when new page-table entries are created, this is only done using the
+ * fault() callback, and never using the value of vma->vm_page_prot,
+ * except for page-table entries that point to anonymous pages as the result
+ * of COW.
+ *
+ * Context: Process context. May allocate using %GFP_KERNEL.
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn, pgprot_t pgprot)
+{
+ return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
+}
+EXPORT_SYMBOL(vmf_insert_mixed_prot);
+
+vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn)
+{
+ return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
+}
+EXPORT_SYMBOL(vmf_insert_mixed);
+
+/*
+ * If the insertion of PTE failed because someone else already added a
+ * different entry in the mean time, we treat that as success as we assume
+ * the same entry was actually inserted.
+ */
+vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
+ unsigned long addr, pfn_t pfn)
+{
+ return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
+}
+EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
+
+/*
+ * maps a range of physical memory into the requested pages. the old
+ * mappings are removed. any references to nonexistent pages results
+ * in null mappings (currently treated as "copy-on-access")
+ */
+static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ unsigned long pfn, pgprot_t prot)
+{
+ pte_t *pte, *mapped_pte;
+ spinlock_t *ptl;
+ int err = 0;
+
+ mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
+ if (!pte)
+ return -ENOMEM;
+ arch_enter_lazy_mmu_mode();
+ do {
+ BUG_ON(!pte_none(*pte));
+ if (!pfn_modify_allowed(pfn, prot)) {
+ err = -EACCES;
+ break;
+ }
+ set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
+ pfn++;
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ arch_leave_lazy_mmu_mode();
+ pte_unmap_unlock(mapped_pte, ptl);
+ return err;
+}
+
+static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
+ unsigned long addr, unsigned long end,
+ unsigned long pfn, pgprot_t prot)
+{
+ pmd_t *pmd;
+ unsigned long next;
+ int err;
+
+ pfn -= addr >> PAGE_SHIFT;
+ pmd = pmd_alloc(mm, pud, addr);
+ if (!pmd)
+ return -ENOMEM;
+ VM_BUG_ON(pmd_trans_huge(*pmd));
+ do {
+ next = pmd_addr_end(addr, end);
+ err = remap_pte_range(mm, pmd, addr, next,
+ pfn + (addr >> PAGE_SHIFT), prot);
+ if (err)
+ return err;
+ } while (pmd++, addr = next, addr != end);
+ return 0;
+}
+
+static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
+ unsigned long addr, unsigned long end,
+ unsigned long pfn, pgprot_t prot)
+{
+ pud_t *pud;
+ unsigned long next;
+ int err;
+
+ pfn -= addr >> PAGE_SHIFT;
+ pud = pud_alloc(mm, p4d, addr);
+ if (!pud)
+ return -ENOMEM;
+ do {
+ next = pud_addr_end(addr, end);
+ err = remap_pmd_range(mm, pud, addr, next,
+ pfn + (addr >> PAGE_SHIFT), prot);
+ if (err)
+ return err;
+ } while (pud++, addr = next, addr != end);
+ return 0;
+}
+
+static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
+ unsigned long addr, unsigned long end,
+ unsigned long pfn, pgprot_t prot)
+{
+ p4d_t *p4d;
+ unsigned long next;
+ int err;
+
+ pfn -= addr >> PAGE_SHIFT;
+ p4d = p4d_alloc(mm, pgd, addr);
+ if (!p4d)
+ return -ENOMEM;
+ do {
+ next = p4d_addr_end(addr, end);
+ err = remap_pud_range(mm, p4d, addr, next,
+ pfn + (addr >> PAGE_SHIFT), prot);
+ if (err)
+ return err;
+ } while (p4d++, addr = next, addr != end);
+ return 0;
+}
+
+/*
+ * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
+ * must have pre-validated the caching bits of the pgprot_t.
+ */
+int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+ pgd_t *pgd;
+ unsigned long next;
+ unsigned long end = addr + PAGE_ALIGN(size);
+ struct mm_struct *mm = vma->vm_mm;
+ int err;
+
+ if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
+ return -EINVAL;
+
+ /*
+ * Physically remapped pages are special. Tell the
+ * rest of the world about it:
+ * VM_IO tells people not to look at these pages
+ * (accesses can have side effects).
+ * VM_PFNMAP tells the core MM that the base pages are just
+ * raw PFN mappings, and do not have a "struct page" associated
+ * with them.
+ * VM_DONTEXPAND
+ * Disable vma merging and expanding with mremap().
+ * VM_DONTDUMP
+ * Omit vma from core dump, even when VM_IO turned off.
+ *
+ * There's a horrible special case to handle copy-on-write
+ * behaviour that some programs depend on. We mark the "original"
+ * un-COW'ed pages by matching them up with "vma->vm_pgoff".
+ * See vm_normal_page() for details.
+ */
+ if (is_cow_mapping(vma->vm_flags)) {
+ if (addr != vma->vm_start || end != vma->vm_end)
+ return -EINVAL;
+ vma->vm_pgoff = pfn;
+ }
+
+ vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+
+ BUG_ON(addr >= end);
+ pfn -= addr >> PAGE_SHIFT;
+ pgd = pgd_offset(mm, addr);
+ flush_cache_range(vma, addr, end);
+ do {
+ next = pgd_addr_end(addr, end);
+ err = remap_p4d_range(mm, pgd, addr, next,
+ pfn + (addr >> PAGE_SHIFT), prot);
+ if (err)
+ return err;
+ } while (pgd++, addr = next, addr != end);
+
+ return 0;
+}
+
+/**
+ * remap_pfn_range - remap kernel memory to userspace
+ * @vma: user vma to map to
+ * @addr: target page aligned user address to start at
+ * @pfn: page frame number of kernel physical memory address
+ * @size: size of mapping area
+ * @prot: page protection flags for this mapping
+ *
+ * Note: this is only safe if the mm semaphore is held when called.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+ int err;
+
+ err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
+ if (err)
+ return -EINVAL;
+
+ err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
+ if (err)
+ untrack_pfn(vma, pfn, PAGE_ALIGN(size));
+ return err;
+}
+EXPORT_SYMBOL(remap_pfn_range);
+
+/**
+ * vm_iomap_memory - remap memory to userspace
+ * @vma: user vma to map to
+ * @start: start of the physical memory to be mapped
+ * @len: size of area
+ *
+ * This is a simplified io_remap_pfn_range() for common driver use. The
+ * driver just needs to give us the physical memory range to be mapped,
+ * we'll figure out the rest from the vma information.
+ *
+ * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
+ * whatever write-combining details or similar.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
+{
+ unsigned long vm_len, pfn, pages;
+
+ /* Check that the physical memory area passed in looks valid */
+ if (start + len < start)
+ return -EINVAL;
+ /*
+ * You *really* shouldn't map things that aren't page-aligned,
+ * but we've historically allowed it because IO memory might
+ * just have smaller alignment.
+ */
+ len += start & ~PAGE_MASK;
+ pfn = start >> PAGE_SHIFT;
+ pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
+ if (pfn + pages < pfn)
+ return -EINVAL;
+
+ /* We start the mapping 'vm_pgoff' pages into the area */
+ if (vma->vm_pgoff > pages)
+ return -EINVAL;
+ pfn += vma->vm_pgoff;
+ pages -= vma->vm_pgoff;
+
+ /* Can we fit all of the mapping? */
+ vm_len = vma->vm_end - vma->vm_start;
+ if (vm_len >> PAGE_SHIFT > pages)
+ return -EINVAL;
+
+ /* Ok, let it rip */
+ return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_iomap_memory);
+
+static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
+{
+ pte_t *pte, *mapped_pte;
+ int err = 0;
+ spinlock_t *ptl;
+
+ if (create) {
+ mapped_pte = pte = (mm == &init_mm) ?
+ pte_alloc_kernel_track(pmd, addr, mask) :
+ pte_alloc_map_lock(mm, pmd, addr, &ptl);
+ if (!pte)
+ return -ENOMEM;
+ } else {
+ mapped_pte = pte = (mm == &init_mm) ?
+ pte_offset_kernel(pmd, addr) :
+ pte_offset_map_lock(mm, pmd, addr, &ptl);
+ }
+
+ BUG_ON(pmd_huge(*pmd));
+
+ arch_enter_lazy_mmu_mode();
+
+ if (fn) {
+ do {
+ if (create || !pte_none(*pte)) {
+ err = fn(pte++, addr, data);
+ if (err)
+ break;
+ }
+ } while (addr += PAGE_SIZE, addr != end);
+ }
+ *mask |= PGTBL_PTE_MODIFIED;
+
+ arch_leave_lazy_mmu_mode();
+
+ if (mm != &init_mm)
+ pte_unmap_unlock(mapped_pte, ptl);
+ return err;
+}
+
+static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
+ unsigned long addr, unsigned long end,
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
+{
+ pmd_t *pmd;
+ unsigned long next;
+ int err = 0;
+
+ BUG_ON(pud_huge(*pud));
+
+ if (create) {
+ pmd = pmd_alloc_track(mm, pud, addr, mask);
+ if (!pmd)
+ return -ENOMEM;
+ } else {
+ pmd = pmd_offset(pud, addr);
+ }
+ do {
+ next = pmd_addr_end(addr, end);
+ if (pmd_none(*pmd) && !create)
+ continue;
+ if (WARN_ON_ONCE(pmd_leaf(*pmd)))
+ return -EINVAL;
+ if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
+ if (!create)
+ continue;
+ pmd_clear_bad(pmd);
+ }
+ err = apply_to_pte_range(mm, pmd, addr, next,
+ fn, data, create, mask);
+ if (err)
+ break;
+ } while (pmd++, addr = next, addr != end);
+
+ return err;
+}
+
+static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
+ unsigned long addr, unsigned long end,
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
+{
+ pud_t *pud;
+ unsigned long next;
+ int err = 0;
+
+ if (create) {
+ pud = pud_alloc_track(mm, p4d, addr, mask);
+ if (!pud)
+ return -ENOMEM;
+ } else {
+ pud = pud_offset(p4d, addr);
+ }
+ do {
+ next = pud_addr_end(addr, end);
+ if (pud_none(*pud) && !create)
+ continue;
+ if (WARN_ON_ONCE(pud_leaf(*pud)))
+ return -EINVAL;
+ if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
+ if (!create)
+ continue;
+ pud_clear_bad(pud);
+ }
+ err = apply_to_pmd_range(mm, pud, addr, next,
+ fn, data, create, mask);
+ if (err)
+ break;
+ } while (pud++, addr = next, addr != end);
+
+ return err;
+}
+
+static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
+ unsigned long addr, unsigned long end,
+ pte_fn_t fn, void *data, bool create,
+ pgtbl_mod_mask *mask)
+{
+ p4d_t *p4d;
+ unsigned long next;
+ int err = 0;
+
+ if (create) {
+ p4d = p4d_alloc_track(mm, pgd, addr, mask);
+ if (!p4d)
+ return -ENOMEM;
+ } else {
+ p4d = p4d_offset(pgd, addr);
+ }
+ do {
+ next = p4d_addr_end(addr, end);
+ if (p4d_none(*p4d) && !create)
+ continue;
+ if (WARN_ON_ONCE(p4d_leaf(*p4d)))
+ return -EINVAL;
+ if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
+ if (!create)
+ continue;
+ p4d_clear_bad(p4d);
+ }
+ err = apply_to_pud_range(mm, p4d, addr, next,
+ fn, data, create, mask);
+ if (err)
+ break;
+ } while (p4d++, addr = next, addr != end);
+
+ return err;
+}
+
+static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn,
+ void *data, bool create)
+{
+ pgd_t *pgd;
+ unsigned long start = addr, next;
+ unsigned long end = addr + size;
+ pgtbl_mod_mask mask = 0;
+ int err = 0;
+
+ if (WARN_ON(addr >= end))
+ return -EINVAL;
+
+ pgd = pgd_offset(mm, addr);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none(*pgd) && !create)
+ continue;
+ if (WARN_ON_ONCE(pgd_leaf(*pgd)))
+ return -EINVAL;
+ if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
+ if (!create)
+ continue;
+ pgd_clear_bad(pgd);
+ }
+ err = apply_to_p4d_range(mm, pgd, addr, next,
+ fn, data, create, &mask);
+ if (err)
+ break;
+ } while (pgd++, addr = next, addr != end);
+
+ if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+ arch_sync_kernel_mappings(start, start + size);
+
+ return err;
+}
+
+/*
+ * Scan a region of virtual memory, filling in page tables as necessary
+ * and calling a provided function on each leaf page table.
+ */
+int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn, void *data)
+{
+ return __apply_to_page_range(mm, addr, size, fn, data, true);
+}
+EXPORT_SYMBOL_GPL(apply_to_page_range);
+
+/*
+ * Scan a region of virtual memory, calling a provided function on
+ * each leaf page table where it exists.
+ *
+ * Unlike apply_to_page_range, this does _not_ fill in page tables
+ * where they are absent.
+ */
+int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
+ unsigned long size, pte_fn_t fn, void *data)
+{
+ return __apply_to_page_range(mm, addr, size, fn, data, false);
+}
+EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
+
+/*
+ * handle_pte_fault chooses page fault handler according to an entry which was
+ * read non-atomically. Before making any commitment, on those architectures
+ * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
+ * parts, do_swap_page must check under lock before unmapping the pte and
+ * proceeding (but do_wp_page is only called after already making such a check;
+ * and do_anonymous_page can safely check later on).
+ */
+static inline int pte_unmap_same(struct vm_fault *vmf)
+{
+ int same = 1;
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
+ if (sizeof(pte_t) > sizeof(unsigned long)) {
+ spinlock_t *ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
+ spin_lock(ptl);
+ same = pte_same(*vmf->pte, vmf->orig_pte);
+ spin_unlock(ptl);
+ }
+#endif
+ pte_unmap(vmf->pte);
+ vmf->pte = NULL;
+ return same;
+}
+
+/*
+ * Return:
+ * 0: copied succeeded
+ * -EHWPOISON: copy failed due to hwpoison in source page
+ * -EAGAIN: copied failed (some other reason)
+ */
+static inline int __wp_page_copy_user(struct page *dst, struct page *src,
+ struct vm_fault *vmf)
+{
+ int ret;
+ void *kaddr;
+ void __user *uaddr;
+ bool locked = false;
+ struct vm_area_struct *vma = vmf->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long addr = vmf->address;
+
+ if (likely(src)) {
+ if (copy_mc_user_highpage(dst, src, addr, vma)) {
+ memory_failure_queue(page_to_pfn(src), 0);
+ return -EHWPOISON;
+ }
+ return 0;
+ }
+
+ /*
+ * If the source page was a PFN mapping, we don't have
+ * a "struct page" for it. We do a best-effort copy by
+ * just copying from the original user address. If that
+ * fails, we just zero-fill it. Live with it.
+ */
+ kaddr = kmap_atomic(dst);
+ uaddr = (void __user *)(addr & PAGE_MASK);
+
+ /*
+ * On architectures with software "accessed" bits, we would
+ * take a double page fault, so mark it accessed here.
+ */
+ if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
+ pte_t entry;
+
+ vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
+ locked = true;
+ if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
+ /*
+ * Other thread has already handled the fault
+ * and update local tlb only
+ */
+ update_mmu_tlb(vma, addr, vmf->pte);
+ ret = -EAGAIN;
+ goto pte_unlock;
+ }
+
+ entry = pte_mkyoung(vmf->orig_pte);
+ if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
+ update_mmu_cache(vma, addr, vmf->pte);
+ }
+
+ /*
+ * This really shouldn't fail, because the page is there
+ * in the page tables. But it might just be unreadable,
+ * in which case we just give up and fill the result with
+ * zeroes.
+ */
+ if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
+ if (locked)
+ goto warn;
+
+ /* Re-validate under PTL if the page is still mapped */
+ vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
+ locked = true;
+ if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
+ /* The PTE changed under us, update local tlb */
+ update_mmu_tlb(vma, addr, vmf->pte);
+ ret = -EAGAIN;
+ goto pte_unlock;
+ }
+
+ /*
+ * The same page can be mapped back since last copy attempt.
+ * Try to copy again under PTL.
+ */
+ if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
+ /*
+ * Give a warn in case there can be some obscure
+ * use-case
+ */
+warn:
+ WARN_ON_ONCE(1);
+ clear_page(kaddr);
+ }
+ }
+
+ ret = 0;
+
+pte_unlock:
+ if (locked)
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ kunmap_atomic(kaddr);
+ flush_dcache_page(dst);
+
+ return ret;
+}
+
+static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
+{
+ struct file *vm_file = vma->vm_file;
+
+ if (vm_file)
+ return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
+
+ /*
+ * Special mappings (e.g. VDSO) do not have any file so fake
+ * a default GFP_KERNEL for them.
+ */
+ return GFP_KERNEL;
+}
+
+/*
+ * Notify the address space that the page is about to become writable so that
+ * it can prohibit this or wait for the page to get into an appropriate state.
+ *
+ * We do this without the lock held, so that it can sleep if it needs to.
+ */
+static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
+{
+ vm_fault_t ret;
+ struct page *page = vmf->page;
+ unsigned int old_flags = vmf->flags;
+
+ vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
+
+ if (vmf->vma->vm_file &&
+ IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
+ return VM_FAULT_SIGBUS;
+
+ ret = vmf->vma->vm_ops->page_mkwrite(vmf);
+ /* Restore original flags so that caller is not surprised */
+ vmf->flags = old_flags;
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
+ return ret;
+ if (unlikely(!(ret & VM_FAULT_LOCKED))) {
+ lock_page(page);
+ if (!page->mapping) {
+ unlock_page(page);
+ return 0; /* retry */
+ }
+ ret |= VM_FAULT_LOCKED;
+ } else
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ return ret;
+}
+
+/*
+ * Handle dirtying of a page in shared file mapping on a write fault.
+ *
+ * The function expects the page to be locked and unlocks it.
+ */
+static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct address_space *mapping;
+ struct page *page = vmf->page;
+ bool dirtied;
+ bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
+
+ dirtied = set_page_dirty(page);
+ VM_BUG_ON_PAGE(PageAnon(page), page);
+ /*
+ * Take a local copy of the address_space - page.mapping may be zeroed
+ * by truncate after unlock_page(). The address_space itself remains
+ * pinned by vma->vm_file's reference. We rely on unlock_page()'s
+ * release semantics to prevent the compiler from undoing this copying.
+ */
+ mapping = page_rmapping(page);
+ unlock_page(page);
+
+ if (!page_mkwrite)
+ file_update_time(vma->vm_file);
+
+ /*
+ * Throttle page dirtying rate down to writeback speed.
+ *
+ * mapping may be NULL here because some device drivers do not
+ * set page.mapping but still dirty their pages
+ *
+ * Drop the mmap_lock before waiting on IO, if we can. The file
+ * is pinning the mapping, as per above.
+ */
+ if ((dirtied || page_mkwrite) && mapping) {
+ struct file *fpin;
+
+ fpin = maybe_unlock_mmap_for_io(vmf, NULL);
+ balance_dirty_pages_ratelimited(mapping);
+ if (fpin) {
+ fput(fpin);
+ return VM_FAULT_COMPLETED;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Handle write page faults for pages that can be reused in the current vma
+ *
+ * This can happen either due to the mapping being with the VM_SHARED flag,
+ * or due to us being the last reference standing to the page. In either
+ * case, all we need to do here is to mark the page as writable and update
+ * any related book-keeping.
+ */
+static inline void wp_page_reuse(struct vm_fault *vmf)
+ __releases(vmf->ptl)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct page *page = vmf->page;
+ pte_t entry;
+
+ VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
+ VM_BUG_ON(page && PageAnon(page) && !PageAnonExclusive(page));
+
+ /*
+ * Clear the pages cpupid information as the existing
+ * information potentially belongs to a now completely
+ * unrelated process.
+ */
+ if (page)
+ page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
+
+ flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
+ entry = pte_mkyoung(vmf->orig_pte);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ count_vm_event(PGREUSE);
+}
+
+/*
+ * Handle the case of a page which we actually need to copy to a new page,
+ * either due to COW or unsharing.
+ *
+ * Called with mmap_lock locked and the old page referenced, but
+ * without the ptl held.
+ *
+ * High level logic flow:
+ *
+ * - Allocate a page, copy the content of the old page to the new one.
+ * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
+ * - Take the PTL. If the pte changed, bail out and release the allocated page
+ * - If the pte is still the way we remember it, update the page table and all
+ * relevant references. This includes dropping the reference the page-table
+ * held to the old page, as well as updating the rmap.
+ * - In any case, unlock the PTL and drop the reference we took to the old page.
+ */
+static vm_fault_t wp_page_copy(struct vm_fault *vmf)
+{
+ const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+ struct vm_area_struct *vma = vmf->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *old_page = vmf->page;
+ struct page *new_page = NULL;
+ pte_t entry;
+ int page_copied = 0;
+ struct mmu_notifier_range range;
+ int ret;
+
+ delayacct_wpcopy_start();
+
+ if (unlikely(anon_vma_prepare(vma)))
+ goto oom;
+
+ if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
+ new_page = alloc_zeroed_user_highpage_movable(vma,
+ vmf->address);
+ if (!new_page)
+ goto oom;
+ } else {
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
+ vmf->address);
+ if (!new_page)
+ goto oom;
+
+ ret = __wp_page_copy_user(new_page, old_page, vmf);
+ if (ret) {
+ /*
+ * COW failed, if the fault was solved by other,
+ * it's fine. If not, userspace would re-fault on
+ * the same address and we will handle the fault
+ * from the second attempt.
+ * The -EHWPOISON case will not be retried.
+ */
+ put_page(new_page);
+ if (old_page)
+ put_page(old_page);
+
+ delayacct_wpcopy_end();
+ return ret == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
+ }
+ kmsan_copy_page_meta(new_page, old_page);
+ }
+
+ if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL))
+ goto oom_free_new;
+ cgroup_throttle_swaprate(new_page, GFP_KERNEL);
+
+ __SetPageUptodate(new_page);
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
+ vmf->address & PAGE_MASK,
+ (vmf->address & PAGE_MASK) + PAGE_SIZE);
+ mmu_notifier_invalidate_range_start(&range);
+
+ /*
+ * Re-check the pte - we dropped the lock
+ */
+ vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
+ if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
+ if (old_page) {
+ if (!PageAnon(old_page)) {
+ dec_mm_counter_fast(mm,
+ mm_counter_file(old_page));
+ inc_mm_counter_fast(mm, MM_ANONPAGES);
+ }
+ } else {
+ inc_mm_counter_fast(mm, MM_ANONPAGES);
+ }
+ flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
+ entry = mk_pte(new_page, vma->vm_page_prot);
+ entry = pte_sw_mkyoung(entry);
+ if (unlikely(unshare)) {
+ if (pte_soft_dirty(vmf->orig_pte))
+ entry = pte_mksoft_dirty(entry);
+ if (pte_uffd_wp(vmf->orig_pte))
+ entry = pte_mkuffd_wp(entry);
+ } else {
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ }
+
+ /*
+ * Clear the pte entry and flush it first, before updating the
+ * pte with the new entry, to keep TLBs on different CPUs in
+ * sync. This code used to set the new PTE then flush TLBs, but
+ * that left a window where the new PTE could be loaded into
+ * some TLBs while the old PTE remains in others.
+ */
+ ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
+ page_add_new_anon_rmap(new_page, vma, vmf->address);
+ lru_cache_add_inactive_or_unevictable(new_page, vma);
+ /*
+ * We call the notify macro here because, when using secondary
+ * mmu page tables (such as kvm shadow page tables), we want the
+ * new page to be mapped directly into the secondary page table.
+ */
+ BUG_ON(unshare && pte_write(entry));
+ set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+ if (old_page) {
+ /*
+ * Only after switching the pte to the new page may
+ * we remove the mapcount here. Otherwise another
+ * process may come and find the rmap count decremented
+ * before the pte is switched to the new page, and
+ * "reuse" the old page writing into it while our pte
+ * here still points into it and can be read by other
+ * threads.
+ *
+ * The critical issue is to order this
+ * page_remove_rmap with the ptp_clear_flush above.
+ * Those stores are ordered by (if nothing else,)
+ * the barrier present in the atomic_add_negative
+ * in page_remove_rmap.
+ *
+ * Then the TLB flush in ptep_clear_flush ensures that
+ * no process can access the old page before the
+ * decremented mapcount is visible. And the old page
+ * cannot be reused until after the decremented
+ * mapcount is visible. So transitively, TLBs to
+ * old page will be flushed before it can be reused.
+ */
+ page_remove_rmap(old_page, vma, false);
+ }
+
+ /* Free the old page.. */
+ new_page = old_page;
+ page_copied = 1;
+ } else {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
+ }
+
+ if (new_page)
+ put_page(new_page);
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ /*
+ * No need to double call mmu_notifier->invalidate_range() callback as
+ * the above ptep_clear_flush_notify() did already call it.
+ */
+ mmu_notifier_invalidate_range_only_end(&range);
+ if (old_page) {
+ if (page_copied)
+ free_swap_cache(old_page);
+ put_page(old_page);
+ }
+
+ delayacct_wpcopy_end();
+ return (page_copied && !unshare) ? VM_FAULT_WRITE : 0;
+oom_free_new:
+ put_page(new_page);
+oom:
+ if (old_page)
+ put_page(old_page);
+
+ delayacct_wpcopy_end();
+ return VM_FAULT_OOM;
+}
+
+/**
+ * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
+ * writeable once the page is prepared
+ *
+ * @vmf: structure describing the fault
+ *
+ * This function handles all that is needed to finish a write page fault in a
+ * shared mapping due to PTE being read-only once the mapped page is prepared.
+ * It handles locking of PTE and modifying it.
+ *
+ * The function expects the page to be locked or other protection against
+ * concurrent faults / writeback (such as DAX radix tree locks).
+ *
+ * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
+ * we acquired PTE lock.
+ */
+vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf)
+{
+ WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
+ vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
+ &vmf->ptl);
+ /*
+ * We might have raced with another page fault while we released the
+ * pte_offset_map_lock.
+ */
+ if (!pte_same(*vmf->pte, vmf->orig_pte)) {
+ update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return VM_FAULT_NOPAGE;
+ }
+ wp_page_reuse(vmf);
+ return 0;
+}
+
+/*
+ * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
+ * mapping
+ */
+static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+
+ if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
+ vm_fault_t ret;
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ vmf->flags |= FAULT_FLAG_MKWRITE;
+ ret = vma->vm_ops->pfn_mkwrite(vmf);
+ if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
+ return ret;
+ return finish_mkwrite_fault(vmf);
+ }
+ wp_page_reuse(vmf);
+ return VM_FAULT_WRITE;
+}
+
+static vm_fault_t wp_page_shared(struct vm_fault *vmf)
+ __releases(vmf->ptl)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ vm_fault_t ret = VM_FAULT_WRITE;
+
+ get_page(vmf->page);
+
+ if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
+ vm_fault_t tmp;
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ tmp = do_page_mkwrite(vmf);
+ if (unlikely(!tmp || (tmp &
+ (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+ put_page(vmf->page);
+ return tmp;
+ }
+ tmp = finish_mkwrite_fault(vmf);
+ if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
+ unlock_page(vmf->page);
+ put_page(vmf->page);
+ return tmp;
+ }
+ } else {
+ wp_page_reuse(vmf);
+ lock_page(vmf->page);
+ }
+ ret |= fault_dirty_shared_page(vmf);
+ put_page(vmf->page);
+
+ return ret;
+}
+
+/*
+ * This routine handles present pages, when
+ * * users try to write to a shared page (FAULT_FLAG_WRITE)
+ * * GUP wants to take a R/O pin on a possibly shared anonymous page
+ * (FAULT_FLAG_UNSHARE)
+ *
+ * It is done by copying the page to a new address and decrementing the
+ * shared-page counter for the old page.
+ *
+ * Note that this routine assumes that the protection checks have been
+ * done by the caller (the low-level page fault routine in most cases).
+ * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
+ * done any necessary COW.
+ *
+ * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
+ * though the page will change only once the write actually happens. This
+ * avoids a few races, and potentially makes it more efficient.
+ *
+ * We enter with non-exclusive mmap_lock (to exclude vma changes,
+ * but allow concurrent faults), with pte both mapped and locked.
+ * We return with mmap_lock still held, but pte unmapped and unlocked.
+ */
+static vm_fault_t do_wp_page(struct vm_fault *vmf)
+ __releases(vmf->ptl)
+{
+ const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+ struct vm_area_struct *vma = vmf->vma;
+ struct folio *folio;
+
+ VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE));
+ VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE));
+
+ if (likely(!unshare)) {
+ if (userfaultfd_pte_wp(vma, *vmf->pte)) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return handle_userfault(vmf, VM_UFFD_WP);
+ }
+
+ /*
+ * Userfaultfd write-protect can defer flushes. Ensure the TLB
+ * is flushed in this case before copying.
+ */
+ if (unlikely(userfaultfd_wp(vmf->vma) &&
+ mm_tlb_flush_pending(vmf->vma->vm_mm)))
+ flush_tlb_page(vmf->vma, vmf->address);
+ }
+
+ vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
+ if (!vmf->page) {
+ if (unlikely(unshare)) {
+ /* No anonymous page -> nothing to do. */
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return 0;
+ }
+
+ /*
+ * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
+ * VM_PFNMAP VMA.
+ *
+ * We should not cow pages in a shared writeable mapping.
+ * Just mark the pages writable and/or call ops->pfn_mkwrite.
+ */
+ if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
+ (VM_WRITE|VM_SHARED))
+ return wp_pfn_shared(vmf);
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return wp_page_copy(vmf);
+ }
+
+ /*
+ * Take out anonymous pages first, anonymous shared vmas are
+ * not dirty accountable.
+ */
+ folio = page_folio(vmf->page);
+ if (folio_test_anon(folio)) {
+ /*
+ * If the page is exclusive to this process we must reuse the
+ * page without further checks.
+ */
+ if (PageAnonExclusive(vmf->page))
+ goto reuse;
+
+ /*
+ * We have to verify under folio lock: these early checks are
+ * just an optimization to avoid locking the folio and freeing
+ * the swapcache if there is little hope that we can reuse.
+ *
+ * KSM doesn't necessarily raise the folio refcount.
+ */
+ if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
+ goto copy;
+ if (!folio_test_lru(folio))
+ /*
+ * Note: We cannot easily detect+handle references from
+ * remote LRU pagevecs or references to LRU folios.
+ */
+ lru_add_drain();
+ if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
+ goto copy;
+ if (!folio_trylock(folio))
+ goto copy;
+ if (folio_test_swapcache(folio))
+ folio_free_swap(folio);
+ if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
+ folio_unlock(folio);
+ goto copy;
+ }
+ /*
+ * Ok, we've got the only folio reference from our mapping
+ * and the folio is locked, it's dark out, and we're wearing
+ * sunglasses. Hit it.
+ */
+ page_move_anon_rmap(vmf->page, vma);
+ folio_unlock(folio);
+reuse:
+ if (unlikely(unshare)) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return 0;
+ }
+ wp_page_reuse(vmf);
+ return VM_FAULT_WRITE;
+ } else if (unshare) {
+ /* No anonymous page -> nothing to do. */
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return 0;
+ } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
+ (VM_WRITE|VM_SHARED))) {
+ return wp_page_shared(vmf);
+ }
+copy:
+ /*
+ * Ok, we need to copy. Oh, well..
+ */
+ get_page(vmf->page);
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+#ifdef CONFIG_KSM
+ if (PageKsm(vmf->page))
+ count_vm_event(COW_KSM);
+#endif
+ return wp_page_copy(vmf);
+}
+
+static void unmap_mapping_range_vma(struct vm_area_struct *vma,
+ unsigned long start_addr, unsigned long end_addr,
+ struct zap_details *details)
+{
+ zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
+}
+
+static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
+ pgoff_t first_index,
+ pgoff_t last_index,
+ struct zap_details *details)
+{
+ struct vm_area_struct *vma;
+ pgoff_t vba, vea, zba, zea;
+
+ vma_interval_tree_foreach(vma, root, first_index, last_index) {
+ vba = vma->vm_pgoff;
+ vea = vba + vma_pages(vma) - 1;
+ zba = max(first_index, vba);
+ zea = min(last_index, vea);
+
+ unmap_mapping_range_vma(vma,
+ ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
+ ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
+ details);
+ }
+}
+
+/**
+ * unmap_mapping_folio() - Unmap single folio from processes.
+ * @folio: The locked folio to be unmapped.
+ *
+ * Unmap this folio from any userspace process which still has it mmaped.
+ * Typically, for efficiency, the range of nearby pages has already been
+ * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
+ * truncation or invalidation holds the lock on a folio, it may find that
+ * the page has been remapped again: and then uses unmap_mapping_folio()
+ * to unmap it finally.
+ */
+void unmap_mapping_folio(struct folio *folio)
+{
+ struct address_space *mapping = folio->mapping;
+ struct zap_details details = { };
+ pgoff_t first_index;
+ pgoff_t last_index;
+
+ VM_BUG_ON(!folio_test_locked(folio));
+
+ first_index = folio->index;
+ last_index = folio->index + folio_nr_pages(folio) - 1;
+
+ details.even_cows = false;
+ details.single_folio = folio;
+ details.zap_flags = ZAP_FLAG_DROP_MARKER;
+
+ i_mmap_lock_read(mapping);
+ if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
+ unmap_mapping_range_tree(&mapping->i_mmap, first_index,
+ last_index, &details);
+ i_mmap_unlock_read(mapping);
+}
+
+/**
+ * unmap_mapping_pages() - Unmap pages from processes.
+ * @mapping: The address space containing pages to be unmapped.
+ * @start: Index of first page to be unmapped.
+ * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
+ * @even_cows: Whether to unmap even private COWed pages.
+ *
+ * Unmap the pages in this address space from any userspace process which
+ * has them mmaped. Generally, you want to remove COWed pages as well when
+ * a file is being truncated, but not when invalidating pages from the page
+ * cache.
+ */
+void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
+ pgoff_t nr, bool even_cows)
+{
+ struct zap_details details = { };
+ pgoff_t first_index = start;
+ pgoff_t last_index = start + nr - 1;
+
+ details.even_cows = even_cows;
+ if (last_index < first_index)
+ last_index = ULONG_MAX;
+
+ i_mmap_lock_read(mapping);
+ if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
+ unmap_mapping_range_tree(&mapping->i_mmap, first_index,
+ last_index, &details);
+ i_mmap_unlock_read(mapping);
+}
+EXPORT_SYMBOL_GPL(unmap_mapping_pages);
+
+/**
+ * unmap_mapping_range - unmap the portion of all mmaps in the specified
+ * address_space corresponding to the specified byte range in the underlying
+ * file.
+ *
+ * @mapping: the address space containing mmaps to be unmapped.
+ * @holebegin: byte in first page to unmap, relative to the start of
+ * the underlying file. This will be rounded down to a PAGE_SIZE
+ * boundary. Note that this is different from truncate_pagecache(), which
+ * must keep the partial page. In contrast, we must get rid of
+ * partial pages.
+ * @holelen: size of prospective hole in bytes. This will be rounded
+ * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
+ * end of the file.
+ * @even_cows: 1 when truncating a file, unmap even private COWed pages;
+ * but 0 when invalidating pagecache, don't throw away private data.
+ */
+void unmap_mapping_range(struct address_space *mapping,
+ loff_t const holebegin, loff_t const holelen, int even_cows)
+{
+ pgoff_t hba = (pgoff_t)(holebegin) >> PAGE_SHIFT;
+ pgoff_t hlen = ((pgoff_t)(holelen) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+ /* Check for overflow. */
+ if (sizeof(holelen) > sizeof(hlen)) {
+ long long holeend =
+ (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (holeend & ~(long long)ULONG_MAX)
+ hlen = ULONG_MAX - hba + 1;
+ }
+
+ unmap_mapping_pages(mapping, hba, hlen, even_cows);
+}
+EXPORT_SYMBOL(unmap_mapping_range);
+
+/*
+ * Restore a potential device exclusive pte to a working pte entry
+ */
+static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
+{
+ struct folio *folio = page_folio(vmf->page);
+ struct vm_area_struct *vma = vmf->vma;
+ struct mmu_notifier_range range;
+
+ /*
+ * We need a reference to lock the folio because we don't hold
+ * the PTL so a racing thread can remove the device-exclusive
+ * entry and unmap it. If the folio is free the entry must
+ * have been removed already. If it happens to have already
+ * been re-allocated after being freed all we do is lock and
+ * unlock it.
+ */
+ if (!folio_try_get(folio))
+ return 0;
+
+ if (!folio_lock_or_retry(folio, vma->vm_mm, vmf->flags)) {
+ folio_put(folio);
+ return VM_FAULT_RETRY;
+ }
+ mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma,
+ vma->vm_mm, vmf->address & PAGE_MASK,
+ (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
+ mmu_notifier_invalidate_range_start(&range);
+
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
+ &vmf->ptl);
+ if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
+ restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ folio_unlock(folio);
+ folio_put(folio);
+
+ mmu_notifier_invalidate_range_end(&range);
+ return 0;
+}
+
+static inline bool should_try_to_free_swap(struct folio *folio,
+ struct vm_area_struct *vma,
+ unsigned int fault_flags)
+{
+ if (!folio_test_swapcache(folio))
+ return false;
+ if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
+ folio_test_mlocked(folio))
+ return true;
+ /*
+ * If we want to map a page that's in the swapcache writable, we
+ * have to detect via the refcount if we're really the exclusive
+ * user. Try freeing the swapcache to get rid of the swapcache
+ * reference only in case it's likely that we'll be the exlusive user.
+ */
+ return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
+ folio_ref_count(folio) == 2;
+}
+
+static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
+{
+ vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ /*
+ * Be careful so that we will only recover a special uffd-wp pte into a
+ * none pte. Otherwise it means the pte could have changed, so retry.
+ */
+ if (is_pte_marker(*vmf->pte))
+ pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return 0;
+}
+
+/*
+ * This is actually a page-missing access, but with uffd-wp special pte
+ * installed. It means this pte was wr-protected before being unmapped.
+ */
+static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
+{
+ /*
+ * Just in case there're leftover special ptes even after the region
+ * got unregistered - we can simply clear them. We can also do that
+ * proactively when e.g. when we do UFFDIO_UNREGISTER upon some uffd-wp
+ * ranges, but it should be more efficient to be done lazily here.
+ */
+ if (unlikely(!userfaultfd_wp(vmf->vma) || vma_is_anonymous(vmf->vma)))
+ return pte_marker_clear(vmf);
+
+ /* do_fault() can handle pte markers too like none pte */
+ return do_fault(vmf);
+}
+
+static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
+{
+ swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
+ unsigned long marker = pte_marker_get(entry);
+
+ /*
+ * PTE markers should always be with file-backed memories, and the
+ * marker should never be empty. If anything weird happened, the best
+ * thing to do is to kill the process along with its mm.
+ */
+ if (WARN_ON_ONCE(vma_is_anonymous(vmf->vma) || !marker))
+ return VM_FAULT_SIGBUS;
+
+ if (pte_marker_entry_uffd_wp(entry))
+ return pte_marker_handle_uffd_wp(vmf);
+
+ /* This is an unknown pte marker */
+ return VM_FAULT_SIGBUS;
+}
+
+/*
+ * We enter with non-exclusive mmap_lock (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with pte unmapped and unlocked.
+ *
+ * We return with the mmap_lock locked or unlocked in the same cases
+ * as does filemap_fault().
+ */
+vm_fault_t do_swap_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct folio *swapcache, *folio = NULL;
+ struct page *page;
+ struct swap_info_struct *si = NULL;
+ rmap_t rmap_flags = RMAP_NONE;
+ bool exclusive = false;
+ swp_entry_t entry;
+ pte_t pte;
+ int locked;
+ vm_fault_t ret = 0;
+ void *shadow = NULL;
+
+ if (!pte_unmap_same(vmf))
+ goto out;
+
+ entry = pte_to_swp_entry(vmf->orig_pte);
+ if (unlikely(non_swap_entry(entry))) {
+ if (is_migration_entry(entry)) {
+ migration_entry_wait(vma->vm_mm, vmf->pmd,
+ vmf->address);
+ } else if (is_device_exclusive_entry(entry)) {
+ vmf->page = pfn_swap_entry_to_page(entry);
+ ret = remove_device_exclusive_entry(vmf);
+ } else if (is_device_private_entry(entry)) {
+ vmf->page = pfn_swap_entry_to_page(entry);
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
+ spin_unlock(vmf->ptl);
+ goto out;
+ }
+
+ /*
+ * Get a page reference while we know the page can't be
+ * freed.
+ */
+ get_page(vmf->page);
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
+ put_page(vmf->page);
+ } else if (is_hwpoison_entry(entry)) {
+ ret = VM_FAULT_HWPOISON;
+ } else if (is_swapin_error_entry(entry)) {
+ ret = VM_FAULT_SIGBUS;
+ } else if (is_pte_marker_entry(entry)) {
+ ret = handle_pte_marker(vmf);
+ } else {
+ print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
+ ret = VM_FAULT_SIGBUS;
+ }
+ goto out;
+ }
+
+ /* Prevent swapoff from happening to us. */
+ si = get_swap_device(entry);
+ if (unlikely(!si))
+ goto out;
+
+ folio = swap_cache_get_folio(entry, vma, vmf->address);
+ if (folio)
+ page = folio_file_page(folio, swp_offset(entry));
+ swapcache = folio;
+
+ if (!folio) {
+ if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
+ __swap_count(entry) == 1) {
+ /* skip swapcache */
+ folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
+ vma, vmf->address, false);
+ page = &folio->page;
+ if (folio) {
+ __folio_set_locked(folio);
+ __folio_set_swapbacked(folio);
+
+ if (mem_cgroup_swapin_charge_folio(folio,
+ vma->vm_mm, GFP_KERNEL,
+ entry)) {
+ ret = VM_FAULT_OOM;
+ goto out_page;
+ }
+ mem_cgroup_swapin_uncharge_swap(entry);
+
+ shadow = get_shadow_from_swap_cache(entry);
+ if (shadow)
+ workingset_refault(folio, shadow);
+
+ folio_add_lru(folio);
+
+ /* To provide entry to swap_readpage() */
+ folio_set_swap_entry(folio, entry);
+ swap_readpage(page, true, NULL);
+ folio->private = NULL;
+ }
+ } else {
+ page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
+ vmf);
+ if (page)
+ folio = page_folio(page);
+ swapcache = folio;
+ }
+
+ if (!folio) {
+ /*
+ * Back out if somebody else faulted in this pte
+ * while we released the pte lock.
+ */
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
+ ret = VM_FAULT_OOM;
+ goto unlock;
+ }
+
+ /* Had to read the page from swap area: Major fault */
+ ret = VM_FAULT_MAJOR;
+ count_vm_event(PGMAJFAULT);
+ count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
+ } else if (PageHWPoison(page)) {
+ /*
+ * hwpoisoned dirty swapcache pages are kept for killing
+ * owner processes (which may be unknown at hwpoison time)
+ */
+ ret = VM_FAULT_HWPOISON;
+ goto out_release;
+ }
+
+ locked = folio_lock_or_retry(folio, vma->vm_mm, vmf->flags);
+
+ if (!locked) {
+ ret |= VM_FAULT_RETRY;
+ goto out_release;
+ }
+
+ if (swapcache) {
+ /*
+ * Make sure folio_free_swap() or swapoff did not release the
+ * swapcache from under us. The page pin, and pte_same test
+ * below, are not enough to exclude that. Even if it is still
+ * swapcache, we need to check that the page's swap has not
+ * changed.
+ */
+ if (unlikely(!folio_test_swapcache(folio) ||
+ page_private(page) != entry.val))
+ goto out_page;
+
+ /*
+ * KSM sometimes has to copy on read faults, for example, if
+ * page->index of !PageKSM() pages would be nonlinear inside the
+ * anon VMA -- PageKSM() is lost on actual swapout.
+ */
+ page = ksm_might_need_to_copy(page, vma, vmf->address);
+ if (unlikely(!page)) {
+ ret = VM_FAULT_OOM;
+ goto out_page;
+ }
+ folio = page_folio(page);
+
+ /*
+ * If we want to map a page that's in the swapcache writable, we
+ * have to detect via the refcount if we're really the exclusive
+ * owner. Try removing the extra reference from the local LRU
+ * pagevecs if required.
+ */
+ if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
+ !folio_test_ksm(folio) && !folio_test_lru(folio))
+ lru_add_drain();
+ }
+
+ cgroup_throttle_swaprate(page, GFP_KERNEL);
+
+ /*
+ * Back out if somebody else already faulted in this pte.
+ */
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
+ &vmf->ptl);
+ if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
+ goto out_nomap;
+
+ if (unlikely(!folio_test_uptodate(folio))) {
+ ret = VM_FAULT_SIGBUS;
+ goto out_nomap;
+ }
+
+ /*
+ * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
+ * must never point at an anonymous page in the swapcache that is
+ * PG_anon_exclusive. Sanity check that this holds and especially, that
+ * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
+ * check after taking the PT lock and making sure that nobody
+ * concurrently faulted in this page and set PG_anon_exclusive.
+ */
+ BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
+ BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
+
+ /*
+ * Check under PT lock (to protect against concurrent fork() sharing
+ * the swap entry concurrently) for certainly exclusive pages.
+ */
+ if (!folio_test_ksm(folio)) {
+ /*
+ * Note that pte_swp_exclusive() == false for architectures
+ * without __HAVE_ARCH_PTE_SWP_EXCLUSIVE.
+ */
+ exclusive = pte_swp_exclusive(vmf->orig_pte);
+ if (folio != swapcache) {
+ /*
+ * We have a fresh page that is not exposed to the
+ * swapcache -> certainly exclusive.
+ */
+ exclusive = true;
+ } else if (exclusive && folio_test_writeback(folio) &&
+ data_race(si->flags & SWP_STABLE_WRITES)) {
+ /*
+ * This is tricky: not all swap backends support
+ * concurrent page modifications while under writeback.
+ *
+ * So if we stumble over such a page in the swapcache
+ * we must not set the page exclusive, otherwise we can
+ * map it writable without further checks and modify it
+ * while still under writeback.
+ *
+ * For these problematic swap backends, simply drop the
+ * exclusive marker: this is perfectly fine as we start
+ * writeback only if we fully unmapped the page and
+ * there are no unexpected references on the page after
+ * unmapping succeeded. After fully unmapped, no
+ * further GUP references (FOLL_GET and FOLL_PIN) can
+ * appear, so dropping the exclusive marker and mapping
+ * it only R/O is fine.
+ */
+ exclusive = false;
+ }
+ }
+
+ /*
+ * Some architectures may have to restore extra metadata to the page
+ * when reading from swap. This metadata may be indexed by swap entry
+ * so this must be called before swap_free().
+ */
+ arch_swap_restore(entry, folio);
+
+ /*
+ * Remove the swap entry and conditionally try to free up the swapcache.
+ * We're already holding a reference on the page but haven't mapped it
+ * yet.
+ */
+ swap_free(entry);
+ if (should_try_to_free_swap(folio, vma, vmf->flags))
+ folio_free_swap(folio);
+
+ inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
+ dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
+ pte = mk_pte(page, vma->vm_page_prot);
+
+ /*
+ * Same logic as in do_wp_page(); however, optimize for pages that are
+ * certainly not shared either because we just allocated them without
+ * exposing them to the swapcache or because the swap entry indicates
+ * exclusivity.
+ */
+ if (!folio_test_ksm(folio) &&
+ (exclusive || folio_ref_count(folio) == 1)) {
+ if (vmf->flags & FAULT_FLAG_WRITE) {
+ pte = maybe_mkwrite(pte_mkdirty(pte), vma);
+ vmf->flags &= ~FAULT_FLAG_WRITE;
+ ret |= VM_FAULT_WRITE;
+ }
+ rmap_flags |= RMAP_EXCLUSIVE;
+ }
+ flush_icache_page(vma, page);
+ if (pte_swp_soft_dirty(vmf->orig_pte))
+ pte = pte_mksoft_dirty(pte);
+ if (pte_swp_uffd_wp(vmf->orig_pte)) {
+ pte = pte_mkuffd_wp(pte);
+ pte = pte_wrprotect(pte);
+ }
+ vmf->orig_pte = pte;
+
+ /* ksm created a completely new copy */
+ if (unlikely(folio != swapcache && swapcache)) {
+ page_add_new_anon_rmap(page, vma, vmf->address);
+ folio_add_lru_vma(folio, vma);
+ } else {
+ page_add_anon_rmap(page, vma, vmf->address, rmap_flags);
+ }
+
+ VM_BUG_ON(!folio_test_anon(folio) ||
+ (pte_write(pte) && !PageAnonExclusive(page)));
+ set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
+ arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
+
+ folio_unlock(folio);
+ if (folio != swapcache && swapcache) {
+ /*
+ * Hold the lock to avoid the swap entry to be reused
+ * until we take the PT lock for the pte_same() check
+ * (to avoid false positives from pte_same). For
+ * further safety release the lock after the swap_free
+ * so that the swap count won't change under a
+ * parallel locked swapcache.
+ */
+ folio_unlock(swapcache);
+ folio_put(swapcache);
+ }
+
+ if (vmf->flags & FAULT_FLAG_WRITE) {
+ ret |= do_wp_page(vmf);
+ if (ret & VM_FAULT_ERROR)
+ ret &= VM_FAULT_ERROR;
+ goto out;
+ }
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+unlock:
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+out:
+ if (si)
+ put_swap_device(si);
+ return ret;
+out_nomap:
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+out_page:
+ folio_unlock(folio);
+out_release:
+ folio_put(folio);
+ if (folio != swapcache && swapcache) {
+ folio_unlock(swapcache);
+ folio_put(swapcache);
+ }
+ if (si)
+ put_swap_device(si);
+ return ret;
+}
+
+/*
+ * We enter with non-exclusive mmap_lock (to exclude vma changes,
+ * but allow concurrent faults), and pte mapped but not yet locked.
+ * We return with mmap_lock still held, but pte unmapped and unlocked.
+ */
+static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct page *page;
+ vm_fault_t ret = 0;
+ pte_t entry;
+
+ /* File mapping without ->vm_ops ? */
+ if (vma->vm_flags & VM_SHARED)
+ return VM_FAULT_SIGBUS;
+
+ /*
+ * Use pte_alloc() instead of pte_alloc_map(). We can't run
+ * pte_offset_map() on pmds where a huge pmd might be created
+ * from a different thread.
+ *
+ * pte_alloc_map() is safe to use under mmap_write_lock(mm) or when
+ * parallel threads are excluded by other means.
+ *
+ * Here we only have mmap_read_lock(mm).
+ */
+ if (pte_alloc(vma->vm_mm, vmf->pmd))
+ return VM_FAULT_OOM;
+
+ /* See comment in handle_pte_fault() */
+ if (unlikely(pmd_trans_unstable(vmf->pmd)))
+ return 0;
+
+ /* Use the zero-page for reads */
+ if (!(vmf->flags & FAULT_FLAG_WRITE) &&
+ !mm_forbids_zeropage(vma->vm_mm)) {
+ entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
+ vma->vm_page_prot));
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ if (!pte_none(*vmf->pte)) {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
+ goto unlock;
+ }
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ goto unlock;
+ /* Deliver the page fault to userland, check inside PT lock */
+ if (userfaultfd_missing(vma)) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return handle_userfault(vmf, VM_UFFD_MISSING);
+ }
+ goto setpte;
+ }
+
+ /* Allocate our own private page. */
+ if (unlikely(anon_vma_prepare(vma)))
+ goto oom;
+ page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
+ if (!page)
+ goto oom;
+
+ if (mem_cgroup_charge(page_folio(page), vma->vm_mm, GFP_KERNEL))
+ goto oom_free_page;
+ cgroup_throttle_swaprate(page, GFP_KERNEL);
+
+ /*
+ * The memory barrier inside __SetPageUptodate makes sure that
+ * preceding stores to the page contents become visible before
+ * the set_pte_at() write.
+ */
+ __SetPageUptodate(page);
+
+ entry = mk_pte(page, vma->vm_page_prot);
+ entry = pte_sw_mkyoung(entry);
+ if (vma->vm_flags & VM_WRITE)
+ entry = pte_mkwrite(pte_mkdirty(entry));
+
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
+ &vmf->ptl);
+ if (!pte_none(*vmf->pte)) {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
+ goto release;
+ }
+
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ goto release;
+
+ /* Deliver the page fault to userland, check inside PT lock */
+ if (userfaultfd_missing(vma)) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ put_page(page);
+ return handle_userfault(vmf, VM_UFFD_MISSING);
+ }
+
+ inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
+ page_add_new_anon_rmap(page, vma, vmf->address);
+ lru_cache_add_inactive_or_unevictable(page, vma);
+setpte:
+ set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+unlock:
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return ret;
+release:
+ put_page(page);
+ goto unlock;
+oom_free_page:
+ put_page(page);
+oom:
+ return VM_FAULT_OOM;
+}
+
+/*
+ * The mmap_lock must have been held on entry, and may have been
+ * released depending on flags and vma->vm_ops->fault() return value.
+ * See filemap_fault() and __lock_page_retry().
+ */
+static vm_fault_t __do_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ vm_fault_t ret;
+
+ /*
+ * Preallocate pte before we take page_lock because this might lead to
+ * deadlocks for memcg reclaim which waits for pages under writeback:
+ * lock_page(A)
+ * SetPageWriteback(A)
+ * unlock_page(A)
+ * lock_page(B)
+ * lock_page(B)
+ * pte_alloc_one
+ * shrink_page_list
+ * wait_on_page_writeback(A)
+ * SetPageWriteback(B)
+ * unlock_page(B)
+ * # flush A, B to clear the writeback
+ */
+ if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
+ vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
+ if (!vmf->prealloc_pte)
+ return VM_FAULT_OOM;
+ }
+
+ ret = vma->vm_ops->fault(vmf);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
+ VM_FAULT_DONE_COW)))
+ return ret;
+
+ if (unlikely(PageHWPoison(vmf->page))) {
+ struct page *page = vmf->page;
+ vm_fault_t poisonret = VM_FAULT_HWPOISON;
+ if (ret & VM_FAULT_LOCKED) {
+ if (page_mapped(page))
+ unmap_mapping_pages(page_mapping(page),
+ page->index, 1, false);
+ /* Retry if a clean page was removed from the cache. */
+ if (invalidate_inode_page(page))
+ poisonret = VM_FAULT_NOPAGE;
+ unlock_page(page);
+ }
+ put_page(page);
+ vmf->page = NULL;
+ return poisonret;
+ }
+
+ if (unlikely(!(ret & VM_FAULT_LOCKED)))
+ lock_page(vmf->page);
+ else
+ VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
+
+ return ret;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static void deposit_prealloc_pte(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+
+ pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
+ /*
+ * We are going to consume the prealloc table,
+ * count that as nr_ptes.
+ */
+ mm_inc_nr_ptes(vma->vm_mm);
+ vmf->prealloc_pte = NULL;
+}
+
+vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ pmd_t entry;
+ int i;
+ vm_fault_t ret = VM_FAULT_FALLBACK;
+
+ if (!transhuge_vma_suitable(vma, haddr))
+ return ret;
+
+ page = compound_head(page);
+ if (compound_order(page) != HPAGE_PMD_ORDER)
+ return ret;
+
+ /*
+ * Just backoff if any subpage of a THP is corrupted otherwise
+ * the corrupted page may mapped by PMD silently to escape the
+ * check. This kind of THP just can be PTE mapped. Access to
+ * the corrupted subpage should trigger SIGBUS as expected.
+ */
+ if (unlikely(PageHasHWPoisoned(page)))
+ return ret;
+
+ /*
+ * Archs like ppc64 need additional space to store information
+ * related to pte entry. Use the preallocated table for that.
+ */
+ if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
+ vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
+ if (!vmf->prealloc_pte)
+ return VM_FAULT_OOM;
+ }
+
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_none(*vmf->pmd)))
+ goto out;
+
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ flush_icache_page(vma, page + i);
+
+ entry = mk_huge_pmd(page, vma->vm_page_prot);
+ if (write)
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+
+ add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR);
+ page_add_file_rmap(page, vma, true);
+
+ /*
+ * deposit and withdraw with pmd lock held
+ */
+ if (arch_needs_pgtable_deposit())
+ deposit_prealloc_pte(vmf);
+
+ set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
+
+ update_mmu_cache_pmd(vma, haddr, vmf->pmd);
+
+ /* fault is handled */
+ ret = 0;
+ count_vm_event(THP_FILE_MAPPED);
+out:
+ spin_unlock(vmf->ptl);
+ return ret;
+}
+#else
+vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
+{
+ return VM_FAULT_FALLBACK;
+}
+#endif
+
+void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ bool uffd_wp = pte_marker_uffd_wp(vmf->orig_pte);
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+ bool prefault = vmf->address != addr;
+ pte_t entry;
+
+ flush_icache_page(vma, page);
+ entry = mk_pte(page, vma->vm_page_prot);
+
+ if (prefault && arch_wants_old_prefaulted_pte())
+ entry = pte_mkold(entry);
+ else
+ entry = pte_sw_mkyoung(entry);
+
+ if (write)
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (unlikely(uffd_wp))
+ entry = pte_mkuffd_wp(pte_wrprotect(entry));
+ /* copy-on-write page */
+ if (write && !(vma->vm_flags & VM_SHARED)) {
+ inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
+ page_add_new_anon_rmap(page, vma, addr);
+ lru_cache_add_inactive_or_unevictable(page, vma);
+ } else {
+ inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
+ page_add_file_rmap(page, vma, false);
+ }
+ set_pte_at(vma->vm_mm, addr, vmf->pte, entry);
+}
+
+static bool vmf_pte_changed(struct vm_fault *vmf)
+{
+ if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
+ return !pte_same(*vmf->pte, vmf->orig_pte);
+
+ return !pte_none(*vmf->pte);
+}
+
+/**
+ * finish_fault - finish page fault once we have prepared the page to fault
+ *
+ * @vmf: structure describing the fault
+ *
+ * This function handles all that is needed to finish a page fault once the
+ * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
+ * given page, adds reverse page mapping, handles memcg charges and LRU
+ * addition.
+ *
+ * The function expects the page to be locked and on success it consumes a
+ * reference of a page being mapped (for the PTE which maps it).
+ *
+ * Return: %0 on success, %VM_FAULT_ code in case of error.
+ */
+vm_fault_t finish_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct page *page;
+ vm_fault_t ret;
+
+ /* Did we COW the page? */
+ if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
+ page = vmf->cow_page;
+ else
+ page = vmf->page;
+
+ /*
+ * check even for read faults because we might have lost our CoWed
+ * page
+ */
+ if (!(vma->vm_flags & VM_SHARED)) {
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ return ret;
+ }
+
+ if (pmd_none(*vmf->pmd)) {
+ if (PageTransCompound(page)) {
+ ret = do_set_pmd(vmf, page);
+ if (ret != VM_FAULT_FALLBACK)
+ return ret;
+ }
+
+ if (vmf->prealloc_pte)
+ pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
+ else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
+ return VM_FAULT_OOM;
+ }
+
+ /*
+ * See comment in handle_pte_fault() for how this scenario happens, we
+ * need to return NOPAGE so that we drop this page.
+ */
+ if (pmd_devmap_trans_unstable(vmf->pmd))
+ return VM_FAULT_NOPAGE;
+
+ vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+
+ /* Re-check under ptl */
+ if (likely(!vmf_pte_changed(vmf))) {
+ do_set_pte(vmf, page, vmf->address);
+
+ /* no need to invalidate: a not-present page won't be cached */
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+
+ ret = 0;
+ } else {
+ update_mmu_tlb(vma, vmf->address, vmf->pte);
+ ret = VM_FAULT_NOPAGE;
+ }
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return ret;
+}
+
+static unsigned long fault_around_bytes __read_mostly =
+ rounddown_pow_of_two(65536);
+
+#ifdef CONFIG_DEBUG_FS
+static int fault_around_bytes_get(void *data, u64 *val)
+{
+ *val = fault_around_bytes;
+ return 0;
+}
+
+/*
+ * fault_around_bytes must be rounded down to the nearest page order as it's
+ * what do_fault_around() expects to see.
+ */
+static int fault_around_bytes_set(void *data, u64 val)
+{
+ if (val / PAGE_SIZE > PTRS_PER_PTE)
+ return -EINVAL;
+ if (val > PAGE_SIZE)
+ fault_around_bytes = rounddown_pow_of_two(val);
+ else
+ fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
+ return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
+ fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
+
+static int __init fault_around_debugfs(void)
+{
+ debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
+ &fault_around_bytes_fops);
+ return 0;
+}
+late_initcall(fault_around_debugfs);
+#endif
+
+/*
+ * do_fault_around() tries to map few pages around the fault address. The hope
+ * is that the pages will be needed soon and this will lower the number of
+ * faults to handle.
+ *
+ * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
+ * not ready to be mapped: not up-to-date, locked, etc.
+ *
+ * This function doesn't cross the VMA boundaries, in order to call map_pages()
+ * only once.
+ *
+ * fault_around_bytes defines how many bytes we'll try to map.
+ * do_fault_around() expects it to be set to a power of two less than or equal
+ * to PTRS_PER_PTE.
+ *
+ * The virtual address of the area that we map is naturally aligned to
+ * fault_around_bytes rounded down to the machine page size
+ * (and therefore to page order). This way it's easier to guarantee
+ * that we don't cross page table boundaries.
+ */
+static vm_fault_t do_fault_around(struct vm_fault *vmf)
+{
+ unsigned long address = vmf->address, nr_pages, mask;
+ pgoff_t start_pgoff = vmf->pgoff;
+ pgoff_t end_pgoff;
+ int off;
+
+ nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
+ mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
+
+ address = max(address & mask, vmf->vma->vm_start);
+ off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
+ start_pgoff -= off;
+
+ /*
+ * end_pgoff is either the end of the page table, the end of
+ * the vma or nr_pages from start_pgoff, depending what is nearest.
+ */
+ end_pgoff = start_pgoff -
+ ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
+ PTRS_PER_PTE - 1;
+ end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
+ start_pgoff + nr_pages - 1);
+
+ if (pmd_none(*vmf->pmd)) {
+ vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
+ if (!vmf->prealloc_pte)
+ return VM_FAULT_OOM;
+ }
+
+ return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
+}
+
+/* Return true if we should do read fault-around, false otherwise */
+static inline bool should_fault_around(struct vm_fault *vmf)
+{
+ /* No ->map_pages? No way to fault around... */
+ if (!vmf->vma->vm_ops->map_pages)
+ return false;
+
+ if (uffd_disable_fault_around(vmf->vma))
+ return false;
+
+ return fault_around_bytes >> PAGE_SHIFT > 1;
+}
+
+static vm_fault_t do_read_fault(struct vm_fault *vmf)
+{
+ vm_fault_t ret = 0;
+
+ /*
+ * Let's call ->map_pages() first and use ->fault() as fallback
+ * if page by the offset is not ready to be mapped (cold cache or
+ * something).
+ */
+ if (should_fault_around(vmf)) {
+ ret = do_fault_around(vmf);
+ if (ret)
+ return ret;
+ }
+
+ ret = __do_fault(vmf);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ return ret;
+
+ ret |= finish_fault(vmf);
+ unlock_page(vmf->page);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ put_page(vmf->page);
+ return ret;
+}
+
+static vm_fault_t do_cow_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ vm_fault_t ret;
+
+ if (unlikely(anon_vma_prepare(vma)))
+ return VM_FAULT_OOM;
+
+ vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
+ if (!vmf->cow_page)
+ return VM_FAULT_OOM;
+
+ if (mem_cgroup_charge(page_folio(vmf->cow_page), vma->vm_mm,
+ GFP_KERNEL)) {
+ put_page(vmf->cow_page);
+ return VM_FAULT_OOM;
+ }
+ cgroup_throttle_swaprate(vmf->cow_page, GFP_KERNEL);
+
+ ret = __do_fault(vmf);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ goto uncharge_out;
+ if (ret & VM_FAULT_DONE_COW)
+ return ret;
+
+ copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
+ __SetPageUptodate(vmf->cow_page);
+
+ ret |= finish_fault(vmf);
+ unlock_page(vmf->page);
+ put_page(vmf->page);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ goto uncharge_out;
+ return ret;
+uncharge_out:
+ put_page(vmf->cow_page);
+ return ret;
+}
+
+static vm_fault_t do_shared_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ vm_fault_t ret, tmp;
+
+ ret = __do_fault(vmf);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ return ret;
+
+ /*
+ * Check if the backing address space wants to know that the page is
+ * about to become writable
+ */
+ if (vma->vm_ops->page_mkwrite) {
+ unlock_page(vmf->page);
+ tmp = do_page_mkwrite(vmf);
+ if (unlikely(!tmp ||
+ (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
+ put_page(vmf->page);
+ return tmp;
+ }
+ }
+
+ ret |= finish_fault(vmf);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
+ VM_FAULT_RETRY))) {
+ unlock_page(vmf->page);
+ put_page(vmf->page);
+ return ret;
+ }
+
+ ret |= fault_dirty_shared_page(vmf);
+ return ret;
+}
+
+/*
+ * We enter with non-exclusive mmap_lock (to exclude vma changes,
+ * but allow concurrent faults).
+ * The mmap_lock may have been released depending on flags and our
+ * return value. See filemap_fault() and __folio_lock_or_retry().
+ * If mmap_lock is released, vma may become invalid (for example
+ * by other thread calling munmap()).
+ */
+static vm_fault_t do_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct mm_struct *vm_mm = vma->vm_mm;
+ vm_fault_t ret;
+
+ /*
+ * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
+ */
+ if (!vma->vm_ops->fault) {
+ /*
+ * If we find a migration pmd entry or a none pmd entry, which
+ * should never happen, return SIGBUS
+ */
+ if (unlikely(!pmd_present(*vmf->pmd)))
+ ret = VM_FAULT_SIGBUS;
+ else {
+ vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm,
+ vmf->pmd,
+ vmf->address,
+ &vmf->ptl);
+ /*
+ * Make sure this is not a temporary clearing of pte
+ * by holding ptl and checking again. A R/M/W update
+ * of pte involves: take ptl, clearing the pte so that
+ * we don't have concurrent modification by hardware
+ * followed by an update.
+ */
+ if (unlikely(pte_none(*vmf->pte)))
+ ret = VM_FAULT_SIGBUS;
+ else
+ ret = VM_FAULT_NOPAGE;
+
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ }
+ } else if (!(vmf->flags & FAULT_FLAG_WRITE))
+ ret = do_read_fault(vmf);
+ else if (!(vma->vm_flags & VM_SHARED))
+ ret = do_cow_fault(vmf);
+ else
+ ret = do_shared_fault(vmf);
+
+ /* preallocated pagetable is unused: free it */
+ if (vmf->prealloc_pte) {
+ pte_free(vm_mm, vmf->prealloc_pte);
+ vmf->prealloc_pte = NULL;
+ }
+ return ret;
+}
+
+int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
+ unsigned long addr, int page_nid, int *flags)
+{
+ get_page(page);
+
+ count_vm_numa_event(NUMA_HINT_FAULTS);
+ if (page_nid == numa_node_id()) {
+ count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
+ *flags |= TNF_FAULT_LOCAL;
+ }
+
+ return mpol_misplaced(page, vma, addr);
+}
+
+static vm_fault_t do_numa_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct page *page = NULL;
+ int page_nid = NUMA_NO_NODE;
+ int last_cpupid;
+ int target_nid;
+ pte_t pte, old_pte;
+ bool was_writable = pte_savedwrite(vmf->orig_pte);
+ int flags = 0;
+
+ /*
+ * The "pte" at this point cannot be used safely without
+ * validation through pte_unmap_same(). It's of NUMA type but
+ * the pfn may be screwed if the read is non atomic.
+ */
+ vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
+ spin_lock(vmf->ptl);
+ if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ goto out;
+ }
+
+ /* Get the normal PTE */
+ old_pte = ptep_get(vmf->pte);
+ pte = pte_modify(old_pte, vma->vm_page_prot);
+
+ page = vm_normal_page(vma, vmf->address, pte);
+ if (!page || is_zone_device_page(page))
+ goto out_map;
+
+ /* TODO: handle PTE-mapped THP */
+ if (PageCompound(page))
+ goto out_map;
+
+ /*
+ * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
+ * much anyway since they can be in shared cache state. This misses
+ * the case where a mapping is writable but the process never writes
+ * to it but pte_write gets cleared during protection updates and
+ * pte_dirty has unpredictable behaviour between PTE scan updates,
+ * background writeback, dirty balancing and application behaviour.
+ */
+ if (!was_writable)
+ flags |= TNF_NO_GROUP;
+
+ /*
+ * Flag if the page is shared between multiple address spaces. This
+ * is later used when determining whether to group tasks together
+ */
+ if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
+ flags |= TNF_SHARED;
+
+ page_nid = page_to_nid(page);
+ /*
+ * For memory tiering mode, cpupid of slow memory page is used
+ * to record page access time. So use default value.
+ */
+ if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
+ !node_is_toptier(page_nid))
+ last_cpupid = (-1 & LAST_CPUPID_MASK);
+ else
+ last_cpupid = page_cpupid_last(page);
+ target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
+ &flags);
+ if (target_nid == NUMA_NO_NODE) {
+ put_page(page);
+ goto out_map;
+ }
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+
+ /* Migrate to the requested node */
+ if (migrate_misplaced_page(page, vma, target_nid)) {
+ page_nid = target_nid;
+ flags |= TNF_MIGRATED;
+ } else {
+ flags |= TNF_MIGRATE_FAIL;
+ vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
+ spin_lock(vmf->ptl);
+ if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ goto out;
+ }
+ goto out_map;
+ }
+
+out:
+ if (page_nid != NUMA_NO_NODE)
+ task_numa_fault(last_cpupid, page_nid, 1, flags);
+ return 0;
+out_map:
+ /*
+ * Make it present again, depending on how arch implements
+ * non-accessible ptes, some can allow access by kernel mode.
+ */
+ old_pte = ptep_modify_prot_start(vma, vmf->address, vmf->pte);
+ pte = pte_modify(old_pte, vma->vm_page_prot);
+ pte = pte_mkyoung(pte);
+ if (was_writable)
+ pte = pte_mkwrite(pte);
+ ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
+ update_mmu_cache(vma, vmf->address, vmf->pte);
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ goto out;
+}
+
+static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
+{
+ if (vma_is_anonymous(vmf->vma))
+ return do_huge_pmd_anonymous_page(vmf);
+ if (vmf->vma->vm_ops->huge_fault)
+ return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
+ return VM_FAULT_FALLBACK;
+}
+
+/* `inline' is required to avoid gcc 4.1.2 build error */
+static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
+{
+ const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+
+ if (vma_is_anonymous(vmf->vma)) {
+ if (likely(!unshare) &&
+ userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd))
+ return handle_userfault(vmf, VM_UFFD_WP);
+ return do_huge_pmd_wp_page(vmf);
+ }
+ if (vmf->vma->vm_ops->huge_fault) {
+ vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
+
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ }
+
+ /* COW or write-notify handled on pte level: split pmd. */
+ __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
+
+ return VM_FAULT_FALLBACK;
+}
+
+static vm_fault_t create_huge_pud(struct vm_fault *vmf)
+{
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
+ defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+ /* No support for anonymous transparent PUD pages yet */
+ if (vma_is_anonymous(vmf->vma))
+ return VM_FAULT_FALLBACK;
+ if (vmf->vma->vm_ops->huge_fault)
+ return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+ return VM_FAULT_FALLBACK;
+}
+
+static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
+{
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
+ defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+ /* No support for anonymous transparent PUD pages yet */
+ if (vma_is_anonymous(vmf->vma))
+ goto split;
+ if (vmf->vma->vm_ops->huge_fault) {
+ vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ }
+split:
+ /* COW or write-notify not handled on PUD level: split pud.*/
+ __split_huge_pud(vmf->vma, vmf->pud, vmf->address);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+ return VM_FAULT_FALLBACK;
+}
+
+/*
+ * These routines also need to handle stuff like marking pages dirty
+ * and/or accessed for architectures that don't do it in hardware (most
+ * RISC architectures). The early dirtying is also good on the i386.
+ *
+ * There is also a hook called "update_mmu_cache()" that architectures
+ * with external mmu caches can use to update those (ie the Sparc or
+ * PowerPC hashed page tables that act as extended TLBs).
+ *
+ * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
+ * concurrent faults).
+ *
+ * The mmap_lock may have been released depending on flags and our return value.
+ * See filemap_fault() and __folio_lock_or_retry().
+ */
+static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
+{
+ pte_t entry;
+
+ if (unlikely(pmd_none(*vmf->pmd))) {
+ /*
+ * Leave __pte_alloc() until later: because vm_ops->fault may
+ * want to allocate huge page, and if we expose page table
+ * for an instant, it will be difficult to retract from
+ * concurrent faults and from rmap lookups.
+ */
+ vmf->pte = NULL;
+ vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
+ } else {
+ /*
+ * If a huge pmd materialized under us just retry later. Use
+ * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead
+ * of pmd_trans_huge() to ensure the pmd didn't become
+ * pmd_trans_huge under us and then back to pmd_none, as a
+ * result of MADV_DONTNEED running immediately after a huge pmd
+ * fault in a different thread of this mm, in turn leading to a
+ * misleading pmd_trans_huge() retval. All we have to ensure is
+ * that it is a regular pmd that we can walk with
+ * pte_offset_map() and we can do that through an atomic read
+ * in C, which is what pmd_trans_unstable() provides.
+ */
+ if (pmd_devmap_trans_unstable(vmf->pmd))
+ return 0;
+ /*
+ * A regular pmd is established and it can't morph into a huge
+ * pmd from under us anymore at this point because we hold the
+ * mmap_lock read mode and khugepaged takes it in write mode.
+ * So now it's safe to run pte_offset_map().
+ */
+ vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
+ vmf->orig_pte = *vmf->pte;
+ vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
+
+ /*
+ * some architectures can have larger ptes than wordsize,
+ * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
+ * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
+ * accesses. The code below just needs a consistent view
+ * for the ifs and we later double check anyway with the
+ * ptl lock held. So here a barrier will do.
+ */
+ barrier();
+ if (pte_none(vmf->orig_pte)) {
+ pte_unmap(vmf->pte);
+ vmf->pte = NULL;
+ }
+ }
+
+ if (!vmf->pte) {
+ if (vma_is_anonymous(vmf->vma))
+ return do_anonymous_page(vmf);
+ else
+ return do_fault(vmf);
+ }
+
+ if (!pte_present(vmf->orig_pte))
+ return do_swap_page(vmf);
+
+ if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
+ return do_numa_page(vmf);
+
+ vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
+ spin_lock(vmf->ptl);
+ entry = vmf->orig_pte;
+ if (unlikely(!pte_same(*vmf->pte, entry))) {
+ update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
+ goto unlock;
+ }
+ if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
+ if (!pte_write(entry))
+ return do_wp_page(vmf);
+ else if (likely(vmf->flags & FAULT_FLAG_WRITE))
+ entry = pte_mkdirty(entry);
+ }
+ entry = pte_mkyoung(entry);
+ if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
+ vmf->flags & FAULT_FLAG_WRITE)) {
+ update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
+ } else {
+ /* Skip spurious TLB flush for retried page fault */
+ if (vmf->flags & FAULT_FLAG_TRIED)
+ goto unlock;
+ /*
+ * This is needed only for protection faults but the arch code
+ * is not yet telling us if this is a protection fault or not.
+ * This still avoids useless tlb flushes for .text page faults
+ * with threads.
+ */
+ if (vmf->flags & FAULT_FLAG_WRITE)
+ flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
+ }
+unlock:
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ return 0;
+}
+
+/*
+ * By the time we get here, we already hold the mm semaphore
+ *
+ * The mmap_lock may have been released depending on flags and our
+ * return value. See filemap_fault() and __folio_lock_or_retry().
+ */
+static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
+ unsigned long address, unsigned int flags)
+{
+ struct vm_fault vmf = {
+ .vma = vma,
+ .address = address & PAGE_MASK,
+ .real_address = address,
+ .flags = flags,
+ .pgoff = linear_page_index(vma, address),
+ .gfp_mask = __get_fault_gfp_mask(vma),
+ };
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long vm_flags = vma->vm_flags;
+ pgd_t *pgd;
+ p4d_t *p4d;
+ vm_fault_t ret;
+
+ pgd = pgd_offset(mm, address);
+ p4d = p4d_alloc(mm, pgd, address);
+ if (!p4d)
+ return VM_FAULT_OOM;
+
+ vmf.pud = pud_alloc(mm, p4d, address);
+ if (!vmf.pud)
+ return VM_FAULT_OOM;
+retry_pud:
+ if (pud_none(*vmf.pud) &&
+ hugepage_vma_check(vma, vm_flags, false, true, true)) {
+ ret = create_huge_pud(&vmf);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ } else {
+ pud_t orig_pud = *vmf.pud;
+
+ barrier();
+ if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
+
+ /*
+ * TODO once we support anonymous PUDs: NUMA case and
+ * FAULT_FLAG_UNSHARE handling.
+ */
+ if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
+ ret = wp_huge_pud(&vmf, orig_pud);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ } else {
+ huge_pud_set_accessed(&vmf, orig_pud);
+ return 0;
+ }
+ }
+ }
+
+ vmf.pmd = pmd_alloc(mm, vmf.pud, address);
+ if (!vmf.pmd)
+ return VM_FAULT_OOM;
+
+ /* Huge pud page fault raced with pmd_alloc? */
+ if (pud_trans_unstable(vmf.pud))
+ goto retry_pud;
+
+ if (pmd_none(*vmf.pmd) &&
+ hugepage_vma_check(vma, vm_flags, false, true, true)) {
+ ret = create_huge_pmd(&vmf);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ } else {
+ vmf.orig_pmd = *vmf.pmd;
+
+ barrier();
+ if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(vmf.orig_pmd));
+ if (is_pmd_migration_entry(vmf.orig_pmd))
+ pmd_migration_entry_wait(mm, vmf.pmd);
+ return 0;
+ }
+ if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
+ if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
+ return do_huge_pmd_numa_page(&vmf);
+
+ if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
+ !pmd_write(vmf.orig_pmd)) {
+ ret = wp_huge_pmd(&vmf);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ } else {
+ huge_pmd_set_accessed(&vmf);
+ return 0;
+ }
+ }
+ }
+
+ return handle_pte_fault(&vmf);
+}
+
+/**
+ * mm_account_fault - Do page fault accounting
+ *
+ * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
+ * of perf event counters, but we'll still do the per-task accounting to
+ * the task who triggered this page fault.
+ * @address: the faulted address.
+ * @flags: the fault flags.
+ * @ret: the fault retcode.
+ *
+ * This will take care of most of the page fault accounting. Meanwhile, it
+ * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
+ * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
+ * still be in per-arch page fault handlers at the entry of page fault.
+ */
+static inline void mm_account_fault(struct pt_regs *regs,
+ unsigned long address, unsigned int flags,
+ vm_fault_t ret)
+{
+ bool major;
+
+ /*
+ * We don't do accounting for some specific faults:
+ *
+ * - Unsuccessful faults (e.g. when the address wasn't valid). That
+ * includes arch_vma_access_permitted() failing before reaching here.
+ * So this is not a "this many hardware page faults" counter. We
+ * should use the hw profiling for that.
+ *
+ * - Incomplete faults (VM_FAULT_RETRY). They will only be counted
+ * once they're completed.
+ */
+ if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY))
+ return;
+
+ /*
+ * We define the fault as a major fault when the final successful fault
+ * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
+ * handle it immediately previously).
+ */
+ major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
+
+ if (major)
+ current->maj_flt++;
+ else
+ current->min_flt++;
+
+ /*
+ * If the fault is done for GUP, regs will be NULL. We only do the
+ * accounting for the per thread fault counters who triggered the
+ * fault, and we skip the perf event updates.
+ */
+ if (!regs)
+ return;
+
+ if (major)
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
+ else
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
+}
+
+#ifdef CONFIG_LRU_GEN
+static void lru_gen_enter_fault(struct vm_area_struct *vma)
+{
+ /* the LRU algorithm doesn't apply to sequential or random reads */
+ current->in_lru_fault = !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ));
+}
+
+static void lru_gen_exit_fault(void)
+{
+ current->in_lru_fault = false;
+}
+#else
+static void lru_gen_enter_fault(struct vm_area_struct *vma)
+{
+}
+
+static void lru_gen_exit_fault(void)
+{
+}
+#endif /* CONFIG_LRU_GEN */
+
+/*
+ * By the time we get here, we already hold the mm semaphore
+ *
+ * The mmap_lock may have been released depending on flags and our
+ * return value. See filemap_fault() and __folio_lock_or_retry().
+ */
+vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
+ unsigned int flags, struct pt_regs *regs)
+{
+ vm_fault_t ret;
+
+ __set_current_state(TASK_RUNNING);
+
+ count_vm_event(PGFAULT);
+ count_memcg_event_mm(vma->vm_mm, PGFAULT);
+
+ /* do counter updates before entering really critical section. */
+ check_sync_rss_stat(current);
+
+ if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
+ flags & FAULT_FLAG_INSTRUCTION,
+ flags & FAULT_FLAG_REMOTE))
+ return VM_FAULT_SIGSEGV;
+
+ /*
+ * Enable the memcg OOM handling for faults triggered in user
+ * space. Kernel faults are handled more gracefully.
+ */
+ if (flags & FAULT_FLAG_USER)
+ mem_cgroup_enter_user_fault();
+
+ lru_gen_enter_fault(vma);
+
+ if (unlikely(is_vm_hugetlb_page(vma)))
+ ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
+ else
+ ret = __handle_mm_fault(vma, address, flags);
+
+ lru_gen_exit_fault();
+
+ if (flags & FAULT_FLAG_USER) {
+ mem_cgroup_exit_user_fault();
+ /*
+ * The task may have entered a memcg OOM situation but
+ * if the allocation error was handled gracefully (no
+ * VM_FAULT_OOM), there is no need to kill anything.
+ * Just clean up the OOM state peacefully.
+ */
+ if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
+ mem_cgroup_oom_synchronize(false);
+ }
+
+ mm_account_fault(regs, address, flags, ret);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(handle_mm_fault);
+
+#ifdef CONFIG_LOCK_MM_AND_FIND_VMA
+#include <linux/extable.h>
+
+static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
+{
+ /* Even if this succeeds, make it clear we *might* have slept */
+ if (likely(mmap_read_trylock(mm))) {
+ might_sleep();
+ return true;
+ }
+
+ if (regs && !user_mode(regs)) {
+ unsigned long ip = instruction_pointer(regs);
+ if (!search_exception_tables(ip))
+ return false;
+ }
+
+ return !mmap_read_lock_killable(mm);
+}
+
+static inline bool mmap_upgrade_trylock(struct mm_struct *mm)
+{
+ /*
+ * We don't have this operation yet.
+ *
+ * It should be easy enough to do: it's basically a
+ * atomic_long_try_cmpxchg_acquire()
+ * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but
+ * it also needs the proper lockdep magic etc.
+ */
+ return false;
+}
+
+static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
+{
+ mmap_read_unlock(mm);
+ if (regs && !user_mode(regs)) {
+ unsigned long ip = instruction_pointer(regs);
+ if (!search_exception_tables(ip))
+ return false;
+ }
+ return !mmap_write_lock_killable(mm);
+}
+
+/*
+ * Helper for page fault handling.
+ *
+ * This is kind of equivalend to "mmap_read_lock()" followed
+ * by "find_extend_vma()", except it's a lot more careful about
+ * the locking (and will drop the lock on failure).
+ *
+ * For example, if we have a kernel bug that causes a page
+ * fault, we don't want to just use mmap_read_lock() to get
+ * the mm lock, because that would deadlock if the bug were
+ * to happen while we're holding the mm lock for writing.
+ *
+ * So this checks the exception tables on kernel faults in
+ * order to only do this all for instructions that are actually
+ * expected to fault.
+ *
+ * We can also actually take the mm lock for writing if we
+ * need to extend the vma, which helps the VM layer a lot.
+ */
+struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
+ unsigned long addr, struct pt_regs *regs)
+{
+ struct vm_area_struct *vma;
+
+ if (!get_mmap_lock_carefully(mm, regs))
+ return NULL;
+
+ vma = find_vma(mm, addr);
+ if (likely(vma && (vma->vm_start <= addr)))
+ return vma;
+
+ /*
+ * Well, dang. We might still be successful, but only
+ * if we can extend a vma to do so.
+ */
+ if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) {
+ mmap_read_unlock(mm);
+ return NULL;
+ }
+
+ /*
+ * We can try to upgrade the mmap lock atomically,
+ * in which case we can continue to use the vma
+ * we already looked up.
+ *
+ * Otherwise we'll have to drop the mmap lock and
+ * re-take it, and also look up the vma again,
+ * re-checking it.
+ */
+ if (!mmap_upgrade_trylock(mm)) {
+ if (!upgrade_mmap_lock_carefully(mm, regs))
+ return NULL;
+
+ vma = find_vma(mm, addr);
+ if (!vma)
+ goto fail;
+ if (vma->vm_start <= addr)
+ goto success;
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ goto fail;
+ }
+
+ if (expand_stack_locked(vma, addr))
+ goto fail;
+
+success:
+ mmap_write_downgrade(mm);
+ return vma;
+
+fail:
+ mmap_write_unlock(mm);
+ return NULL;
+}
+#endif
+
+#ifndef __PAGETABLE_P4D_FOLDED
+/*
+ * Allocate p4d page table.
+ * We've already handled the fast-path in-line.
+ */
+int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
+{
+ p4d_t *new = p4d_alloc_one(mm, address);
+ if (!new)
+ return -ENOMEM;
+
+ spin_lock(&mm->page_table_lock);
+ if (pgd_present(*pgd)) { /* Another has populated it */
+ p4d_free(mm, new);
+ } else {
+ smp_wmb(); /* See comment in pmd_install() */
+ pgd_populate(mm, pgd, new);
+ }
+ spin_unlock(&mm->page_table_lock);
+ return 0;
+}
+#endif /* __PAGETABLE_P4D_FOLDED */
+
+#ifndef __PAGETABLE_PUD_FOLDED
+/*
+ * Allocate page upper directory.
+ * We've already handled the fast-path in-line.
+ */
+int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
+{
+ pud_t *new = pud_alloc_one(mm, address);
+ if (!new)
+ return -ENOMEM;
+
+ spin_lock(&mm->page_table_lock);
+ if (!p4d_present(*p4d)) {
+ mm_inc_nr_puds(mm);
+ smp_wmb(); /* See comment in pmd_install() */
+ p4d_populate(mm, p4d, new);
+ } else /* Another has populated it */
+ pud_free(mm, new);
+ spin_unlock(&mm->page_table_lock);
+ return 0;
+}
+#endif /* __PAGETABLE_PUD_FOLDED */
+
+#ifndef __PAGETABLE_PMD_FOLDED
+/*
+ * Allocate page middle directory.
+ * We've already handled the fast-path in-line.
+ */
+int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
+{
+ spinlock_t *ptl;
+ pmd_t *new = pmd_alloc_one(mm, address);
+ if (!new)
+ return -ENOMEM;
+
+ ptl = pud_lock(mm, pud);
+ if (!pud_present(*pud)) {
+ mm_inc_nr_pmds(mm);
+ smp_wmb(); /* See comment in pmd_install() */
+ pud_populate(mm, pud, new);
+ } else { /* Another has populated it */
+ pmd_free(mm, new);
+ }
+ spin_unlock(ptl);
+ return 0;
+}
+#endif /* __PAGETABLE_PMD_FOLDED */
+
+/**
+ * follow_pte - look up PTE at a user virtual address
+ * @mm: the mm_struct of the target address space
+ * @address: user virtual address
+ * @ptepp: location to store found PTE
+ * @ptlp: location to store the lock for the PTE
+ *
+ * On a successful return, the pointer to the PTE is stored in @ptepp;
+ * the corresponding lock is taken and its location is stored in @ptlp.
+ * The contents of the PTE are only stable until @ptlp is released;
+ * any further use, if any, must be protected against invalidation
+ * with MMU notifiers.
+ *
+ * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
+ * should be taken for read.
+ *
+ * KVM uses this function. While it is arguably less bad than ``follow_pfn``,
+ * it is not a good general-purpose API.
+ *
+ * Return: zero on success, -ve otherwise.
+ */
+int follow_pte(struct mm_struct *mm, unsigned long address,
+ pte_t **ptepp, spinlock_t **ptlp)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep;
+
+ pgd = pgd_offset(mm, address);
+ if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
+ goto out;
+
+ p4d = p4d_offset(pgd, address);
+ if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
+ goto out;
+
+ pud = pud_offset(p4d, address);
+ if (pud_none(*pud) || unlikely(pud_bad(*pud)))
+ goto out;
+
+ pmd = pmd_offset(pud, address);
+ VM_BUG_ON(pmd_trans_huge(*pmd));
+
+ if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+ goto out;
+
+ ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
+ if (!pte_present(*ptep))
+ goto unlock;
+ *ptepp = ptep;
+ return 0;
+unlock:
+ pte_unmap_unlock(ptep, *ptlp);
+out:
+ return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(follow_pte);
+
+/**
+ * follow_pfn - look up PFN at a user virtual address
+ * @vma: memory mapping
+ * @address: user virtual address
+ * @pfn: location to store found PFN
+ *
+ * Only IO mappings and raw PFN mappings are allowed.
+ *
+ * This function does not allow the caller to read the permissions
+ * of the PTE. Do not use it.
+ *
+ * Return: zero and the pfn at @pfn on success, -ve otherwise.
+ */
+int follow_pfn(struct vm_area_struct *vma, unsigned long address,
+ unsigned long *pfn)
+{
+ int ret = -EINVAL;
+ spinlock_t *ptl;
+ pte_t *ptep;
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return ret;
+
+ ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
+ if (ret)
+ return ret;
+ *pfn = pte_pfn(*ptep);
+ pte_unmap_unlock(ptep, ptl);
+ return 0;
+}
+EXPORT_SYMBOL(follow_pfn);
+
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+int follow_phys(struct vm_area_struct *vma,
+ unsigned long address, unsigned int flags,
+ unsigned long *prot, resource_size_t *phys)
+{
+ int ret = -EINVAL;
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ goto out;
+
+ if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
+ goto out;
+ pte = *ptep;
+
+ if ((flags & FOLL_WRITE) && !pte_write(pte))
+ goto unlock;
+
+ *prot = pgprot_val(pte_pgprot(pte));
+ *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+
+ ret = 0;
+unlock:
+ pte_unmap_unlock(ptep, ptl);
+out:
+ return ret;
+}
+
+/**
+ * generic_access_phys - generic implementation for iomem mmap access
+ * @vma: the vma to access
+ * @addr: userspace address, not relative offset within @vma
+ * @buf: buffer to read/write
+ * @len: length of transfer
+ * @write: set to FOLL_WRITE when writing, otherwise reading
+ *
+ * This is a generic implementation for &vm_operations_struct.access for an
+ * iomem mapping. This callback is used by access_process_vm() when the @vma is
+ * not page based.
+ */
+int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write)
+{
+ resource_size_t phys_addr;
+ unsigned long prot = 0;
+ void __iomem *maddr;
+ pte_t *ptep, pte;
+ spinlock_t *ptl;
+ int offset = offset_in_page(addr);
+ int ret = -EINVAL;
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return -EINVAL;
+
+retry:
+ if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
+ return -EINVAL;
+ pte = *ptep;
+ pte_unmap_unlock(ptep, ptl);
+
+ prot = pgprot_val(pte_pgprot(pte));
+ phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+
+ if ((write & FOLL_WRITE) && !pte_write(pte))
+ return -EINVAL;
+
+ maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
+ if (!maddr)
+ return -ENOMEM;
+
+ if (follow_pte(vma->vm_mm, addr, &ptep, &ptl))
+ goto out_unmap;
+
+ if (!pte_same(pte, *ptep)) {
+ pte_unmap_unlock(ptep, ptl);
+ iounmap(maddr);
+
+ goto retry;
+ }
+
+ if (write)
+ memcpy_toio(maddr + offset, buf, len);
+ else
+ memcpy_fromio(buf, maddr + offset, len);
+ ret = len;
+ pte_unmap_unlock(ptep, ptl);
+out_unmap:
+ iounmap(maddr);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(generic_access_phys);
+#endif
+
+/*
+ * Access another process' address space as given in mm.
+ */
+int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
+ int len, unsigned int gup_flags)
+{
+ struct vm_area_struct *vma;
+ void *old_buf = buf;
+ int write = gup_flags & FOLL_WRITE;
+
+ if (mmap_read_lock_killable(mm))
+ return 0;
+
+ /* We might need to expand the stack to access it */
+ vma = vma_lookup(mm, addr);
+ if (!vma) {
+ vma = expand_stack(mm, addr);
+ if (!vma)
+ return 0;
+ }
+
+ /* ignore errors, just check how much was successfully transferred */
+ while (len) {
+ int bytes, ret, offset;
+ void *maddr;
+ struct page *page = NULL;
+
+ ret = get_user_pages_remote(mm, addr, 1,
+ gup_flags, &page, &vma, NULL);
+ if (ret <= 0) {
+#ifndef CONFIG_HAVE_IOREMAP_PROT
+ break;
+#else
+ /*
+ * Check if this is a VM_IO | VM_PFNMAP VMA, which
+ * we can access using slightly different code.
+ */
+ vma = vma_lookup(mm, addr);
+ if (!vma)
+ break;
+ if (vma->vm_ops && vma->vm_ops->access)
+ ret = vma->vm_ops->access(vma, addr, buf,
+ len, write);
+ if (ret <= 0)
+ break;
+ bytes = ret;
+#endif
+ } else {
+ bytes = len;
+ offset = addr & (PAGE_SIZE-1);
+ if (bytes > PAGE_SIZE-offset)
+ bytes = PAGE_SIZE-offset;
+
+ maddr = kmap(page);
+ if (write) {
+ copy_to_user_page(vma, page, addr,
+ maddr + offset, buf, bytes);
+ set_page_dirty_lock(page);
+ } else {
+ copy_from_user_page(vma, page, addr,
+ buf, maddr + offset, bytes);
+ }
+ kunmap(page);
+ put_page(page);
+ }
+ len -= bytes;
+ buf += bytes;
+ addr += bytes;
+ }
+ mmap_read_unlock(mm);
+
+ return buf - old_buf;
+}
+
+/**
+ * access_remote_vm - access another process' address space
+ * @mm: the mm_struct of the target address space
+ * @addr: start address to access
+ * @buf: source or destination buffer
+ * @len: number of bytes to transfer
+ * @gup_flags: flags modifying lookup behaviour
+ *
+ * The caller must hold a reference on @mm.
+ *
+ * Return: number of bytes copied from source to destination.
+ */
+int access_remote_vm(struct mm_struct *mm, unsigned long addr,
+ void *buf, int len, unsigned int gup_flags)
+{
+ return __access_remote_vm(mm, addr, buf, len, gup_flags);
+}
+
+/*
+ * Access another process' address space.
+ * Source/target buffer must be kernel space,
+ * Do not walk the page table directly, use get_user_pages
+ */
+int access_process_vm(struct task_struct *tsk, unsigned long addr,
+ void *buf, int len, unsigned int gup_flags)
+{
+ struct mm_struct *mm;
+ int ret;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return 0;
+
+ ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
+
+ mmput(mm);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(access_process_vm);
+
+/*
+ * Print the name of a VMA.
+ */
+void print_vma_addr(char *prefix, unsigned long ip)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+
+ /*
+ * we might be running from an atomic context so we cannot sleep
+ */
+ if (!mmap_read_trylock(mm))
+ return;
+
+ vma = find_vma(mm, ip);
+ if (vma && vma->vm_file) {
+ struct file *f = vma->vm_file;
+ char *buf = (char *)__get_free_page(GFP_NOWAIT);
+ if (buf) {
+ char *p;
+
+ p = file_path(f, buf, PAGE_SIZE);
+ if (IS_ERR(p))
+ p = "?";
+ printk("%s%s[%lx+%lx]", prefix, kbasename(p),
+ vma->vm_start,
+ vma->vm_end - vma->vm_start);
+ free_page((unsigned long)buf);
+ }
+ }
+ mmap_read_unlock(mm);
+}
+
+#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+void __might_fault(const char *file, int line)
+{
+ if (pagefault_disabled())
+ return;
+ __might_sleep(file, line);
+#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+ if (current->mm)
+ might_lock_read(&current->mm->mmap_lock);
+#endif
+}
+EXPORT_SYMBOL(__might_fault);
+#endif
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
+/*
+ * Process all subpages of the specified huge page with the specified
+ * operation. The target subpage will be processed last to keep its
+ * cache lines hot.
+ */
+static inline void process_huge_page(
+ unsigned long addr_hint, unsigned int pages_per_huge_page,
+ void (*process_subpage)(unsigned long addr, int idx, void *arg),
+ void *arg)
+{
+ int i, n, base, l;
+ unsigned long addr = addr_hint &
+ ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
+
+ /* Process target subpage last to keep its cache lines hot */
+ might_sleep();
+ n = (addr_hint - addr) / PAGE_SIZE;
+ if (2 * n <= pages_per_huge_page) {
+ /* If target subpage in first half of huge page */
+ base = 0;
+ l = n;
+ /* Process subpages at the end of huge page */
+ for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
+ cond_resched();
+ process_subpage(addr + i * PAGE_SIZE, i, arg);
+ }
+ } else {
+ /* If target subpage in second half of huge page */
+ base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
+ l = pages_per_huge_page - n;
+ /* Process subpages at the begin of huge page */
+ for (i = 0; i < base; i++) {
+ cond_resched();
+ process_subpage(addr + i * PAGE_SIZE, i, arg);
+ }
+ }
+ /*
+ * Process remaining subpages in left-right-left-right pattern
+ * towards the target subpage
+ */
+ for (i = 0; i < l; i++) {
+ int left_idx = base + i;
+ int right_idx = base + 2 * l - 1 - i;
+
+ cond_resched();
+ process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
+ cond_resched();
+ process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
+ }
+}
+
+static void clear_gigantic_page(struct page *page,
+ unsigned long addr,
+ unsigned int pages_per_huge_page)
+{
+ int i;
+ struct page *p;
+
+ might_sleep();
+ for (i = 0; i < pages_per_huge_page; i++) {
+ p = nth_page(page, i);
+ cond_resched();
+ clear_user_highpage(p, addr + i * PAGE_SIZE);
+ }
+}
+
+static void clear_subpage(unsigned long addr, int idx, void *arg)
+{
+ struct page *page = arg;
+
+ clear_user_highpage(page + idx, addr);
+}
+
+void clear_huge_page(struct page *page,
+ unsigned long addr_hint, unsigned int pages_per_huge_page)
+{
+ unsigned long addr = addr_hint &
+ ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
+
+ if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+ clear_gigantic_page(page, addr, pages_per_huge_page);
+ return;
+ }
+
+ process_huge_page(addr_hint, pages_per_huge_page, clear_subpage, page);
+}
+
+static void copy_user_gigantic_page(struct page *dst, struct page *src,
+ unsigned long addr,
+ struct vm_area_struct *vma,
+ unsigned int pages_per_huge_page)
+{
+ int i;
+ struct page *dst_base = dst;
+ struct page *src_base = src;
+
+ for (i = 0; i < pages_per_huge_page; i++) {
+ dst = nth_page(dst_base, i);
+ src = nth_page(src_base, i);
+
+ cond_resched();
+ copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
+ }
+}
+
+struct copy_subpage_arg {
+ struct page *dst;
+ struct page *src;
+ struct vm_area_struct *vma;
+};
+
+static void copy_subpage(unsigned long addr, int idx, void *arg)
+{
+ struct copy_subpage_arg *copy_arg = arg;
+
+ copy_user_highpage(copy_arg->dst + idx, copy_arg->src + idx,
+ addr, copy_arg->vma);
+}
+
+void copy_user_huge_page(struct page *dst, struct page *src,
+ unsigned long addr_hint, struct vm_area_struct *vma,
+ unsigned int pages_per_huge_page)
+{
+ unsigned long addr = addr_hint &
+ ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
+ struct copy_subpage_arg arg = {
+ .dst = dst,
+ .src = src,
+ .vma = vma,
+ };
+
+ if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+ copy_user_gigantic_page(dst, src, addr, vma,
+ pages_per_huge_page);
+ return;
+ }
+
+ process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
+}
+
+long copy_huge_page_from_user(struct page *dst_page,
+ const void __user *usr_src,
+ unsigned int pages_per_huge_page,
+ bool allow_pagefault)
+{
+ void *page_kaddr;
+ unsigned long i, rc = 0;
+ unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
+ struct page *subpage;
+
+ for (i = 0; i < pages_per_huge_page; i++) {
+ subpage = nth_page(dst_page, i);
+ if (allow_pagefault)
+ page_kaddr = kmap(subpage);
+ else
+ page_kaddr = kmap_atomic(subpage);
+ rc = copy_from_user(page_kaddr,
+ usr_src + i * PAGE_SIZE, PAGE_SIZE);
+ if (allow_pagefault)
+ kunmap(subpage);
+ else
+ kunmap_atomic(page_kaddr);
+
+ ret_val -= (PAGE_SIZE - rc);
+ if (rc)
+ break;
+
+ flush_dcache_page(subpage);
+
+ cond_resched();
+ }
+ return ret_val;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
+
+#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
+
+static struct kmem_cache *page_ptl_cachep;
+
+void __init ptlock_cache_init(void)
+{
+ page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
+ SLAB_PANIC, NULL);
+}
+
+bool ptlock_alloc(struct page *page)
+{
+ spinlock_t *ptl;
+
+ ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
+ if (!ptl)
+ return false;
+ page->ptl = ptl;
+ return true;
+}
+
+void ptlock_free(struct page *page)
+{
+ kmem_cache_free(page_ptl_cachep, page->ptl);
+}
+#endif