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linux-zen-desktop/mm/madvise.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/mm/madvise.c
*
* Copyright (C) 1999 Linus Torvalds
* Copyright (C) 2002 Christoph Hellwig
*/
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/syscalls.h>
#include <linux/mempolicy.h>
#include <linux/page-isolation.h>
#include <linux/page_idle.h>
#include <linux/userfaultfd_k.h>
#include <linux/hugetlb.h>
#include <linux/falloc.h>
#include <linux/fadvise.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/mm_inline.h>
#include <linux/string.h>
#include <linux/uio.h>
#include <linux/ksm.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/pagewalk.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/shmem_fs.h>
#include <linux/mmu_notifier.h>
#include <asm/tlb.h>
#include "internal.h"
#include "swap.h"
struct madvise_walk_private {
struct mmu_gather *tlb;
bool pageout;
};
/*
* Any behaviour which results in changes to the vma->vm_flags needs to
* take mmap_lock for writing. Others, which simply traverse vmas, need
* to only take it for reading.
*/
static int madvise_need_mmap_write(int behavior)
{
switch (behavior) {
case MADV_REMOVE:
case MADV_WILLNEED:
case MADV_DONTNEED:
case MADV_DONTNEED_LOCKED:
case MADV_COLD:
case MADV_PAGEOUT:
case MADV_FREE:
case MADV_POPULATE_READ:
case MADV_POPULATE_WRITE:
case MADV_COLLAPSE:
return 0;
default:
/* be safe, default to 1. list exceptions explicitly */
return 1;
}
}
#ifdef CONFIG_ANON_VMA_NAME
struct anon_vma_name *anon_vma_name_alloc(const char *name)
{
struct anon_vma_name *anon_name;
size_t count;
/* Add 1 for NUL terminator at the end of the anon_name->name */
count = strlen(name) + 1;
anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
if (anon_name) {
kref_init(&anon_name->kref);
memcpy(anon_name->name, name, count);
}
return anon_name;
}
void anon_vma_name_free(struct kref *kref)
{
struct anon_vma_name *anon_name =
container_of(kref, struct anon_vma_name, kref);
kfree(anon_name);
}
struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
{
mmap_assert_locked(vma->vm_mm);
return vma->anon_name;
}
/* mmap_lock should be write-locked */
static int replace_anon_vma_name(struct vm_area_struct *vma,
struct anon_vma_name *anon_name)
{
struct anon_vma_name *orig_name = anon_vma_name(vma);
if (!anon_name) {
vma->anon_name = NULL;
anon_vma_name_put(orig_name);
return 0;
}
if (anon_vma_name_eq(orig_name, anon_name))
return 0;
vma->anon_name = anon_vma_name_reuse(anon_name);
anon_vma_name_put(orig_name);
return 0;
}
#else /* CONFIG_ANON_VMA_NAME */
static int replace_anon_vma_name(struct vm_area_struct *vma,
struct anon_vma_name *anon_name)
{
if (anon_name)
return -EINVAL;
return 0;
}
#endif /* CONFIG_ANON_VMA_NAME */
/*
* Update the vm_flags on region of a vma, splitting it or merging it as
* necessary. Must be called with mmap_lock held for writing;
* Caller should ensure anon_name stability by raising its refcount even when
* anon_name belongs to a valid vma because this function might free that vma.
*/
static int madvise_update_vma(struct vm_area_struct *vma,
struct vm_area_struct **prev, unsigned long start,
unsigned long end, unsigned long new_flags,
struct anon_vma_name *anon_name)
{
struct mm_struct *mm = vma->vm_mm;
int error;
pgoff_t pgoff;
VMA_ITERATOR(vmi, mm, start);
if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
*prev = vma;
return 0;
}
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
*prev = vma_merge(&vmi, mm, *prev, start, end, new_flags,
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
vma->vm_userfaultfd_ctx, anon_name);
if (*prev) {
vma = *prev;
goto success;
}
*prev = vma;
if (start != vma->vm_start) {
error = split_vma(&vmi, vma, start, 1);
if (error)
return error;
}
if (end != vma->vm_end) {
error = split_vma(&vmi, vma, end, 0);
if (error)
return error;
}
success:
/*
* vm_flags is protected by the mmap_lock held in write mode.
*/
vm_flags_reset(vma, new_flags);
if (!vma->vm_file || vma_is_anon_shmem(vma)) {
error = replace_anon_vma_name(vma, anon_name);
if (error)
return error;
}
return 0;
}
#ifdef CONFIG_SWAP
static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
unsigned long end, struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->private;
unsigned long index;
struct swap_iocb *splug = NULL;
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
return 0;
for (index = start; index != end; index += PAGE_SIZE) {
pte_t pte;
swp_entry_t entry;
struct page *page;
spinlock_t *ptl;
pte_t *ptep;
ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
pte = *ptep;
pte_unmap_unlock(ptep, ptl);
if (!is_swap_pte(pte))
continue;
entry = pte_to_swp_entry(pte);
if (unlikely(non_swap_entry(entry)))
continue;
page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
vma, index, false, &splug);
if (page)
put_page(page);
}
swap_read_unplug(splug);
cond_resched();
return 0;
}
static const struct mm_walk_ops swapin_walk_ops = {
.pmd_entry = swapin_walk_pmd_entry,
};
static void force_shm_swapin_readahead(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct address_space *mapping)
{
XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
struct page *page;
struct swap_iocb *splug = NULL;
rcu_read_lock();
xas_for_each(&xas, page, end_index) {
swp_entry_t swap;
if (!xa_is_value(page))
continue;
swap = radix_to_swp_entry(page);
/* There might be swapin error entries in shmem mapping. */
if (non_swap_entry(swap))
continue;
xas_pause(&xas);
rcu_read_unlock();
page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
NULL, 0, false, &splug);
if (page)
put_page(page);
rcu_read_lock();
}
rcu_read_unlock();
swap_read_unplug(splug);
lru_add_drain(); /* Push any new pages onto the LRU now */
}
#endif /* CONFIG_SWAP */
/*
* Schedule all required I/O operations. Do not wait for completion.
*/
static long madvise_willneed(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
struct file *file = vma->vm_file;
loff_t offset;
*prev = vma;
#ifdef CONFIG_SWAP
if (!file) {
walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
lru_add_drain(); /* Push any new pages onto the LRU now */
return 0;
}
if (shmem_mapping(file->f_mapping)) {
force_shm_swapin_readahead(vma, start, end,
file->f_mapping);
return 0;
}
#else
if (!file)
return -EBADF;
#endif
if (IS_DAX(file_inode(file))) {
/* no bad return value, but ignore advice */
return 0;
}
/*
* Filesystem's fadvise may need to take various locks. We need to
* explicitly grab a reference because the vma (and hence the
* vma's reference to the file) can go away as soon as we drop
* mmap_lock.
*/
*prev = NULL; /* tell sys_madvise we drop mmap_lock */
get_file(file);
offset = (loff_t)(start - vma->vm_start)
+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
mmap_read_unlock(mm);
vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
fput(file);
mmap_read_lock(mm);
return 0;
}
static inline bool can_do_file_pageout(struct vm_area_struct *vma)
{
if (!vma->vm_file)
return false;
/*
* paging out pagecache only for non-anonymous mappings that correspond
* to the files the calling process could (if tried) open for writing;
* otherwise we'd be including shared non-exclusive mappings, which
* opens a side channel.
*/
return inode_owner_or_capable(&nop_mnt_idmap,
file_inode(vma->vm_file)) ||
file_permission(vma->vm_file, MAY_WRITE) == 0;
}
static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct madvise_walk_private *private = walk->private;
struct mmu_gather *tlb = private->tlb;
bool pageout = private->pageout;
struct mm_struct *mm = tlb->mm;
struct vm_area_struct *vma = walk->vma;
pte_t *orig_pte, *pte, ptent;
spinlock_t *ptl;
struct folio *folio = NULL;
LIST_HEAD(folio_list);
bool pageout_anon_only_filter;
if (fatal_signal_pending(current))
return -EINTR;
pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
!can_do_file_pageout(vma);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (pmd_trans_huge(*pmd)) {
pmd_t orig_pmd;
unsigned long next = pmd_addr_end(addr, end);
tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
ptl = pmd_trans_huge_lock(pmd, vma);
if (!ptl)
return 0;
orig_pmd = *pmd;
if (is_huge_zero_pmd(orig_pmd))
goto huge_unlock;
if (unlikely(!pmd_present(orig_pmd))) {
VM_BUG_ON(thp_migration_supported() &&
!is_pmd_migration_entry(orig_pmd));
goto huge_unlock;
}
folio = pfn_folio(pmd_pfn(orig_pmd));
/* Do not interfere with other mappings of this folio */
if (folio_mapcount(folio) != 1)
goto huge_unlock;
if (pageout_anon_only_filter && !folio_test_anon(folio))
goto huge_unlock;
if (next - addr != HPAGE_PMD_SIZE) {
int err;
folio_get(folio);
spin_unlock(ptl);
folio_lock(folio);
err = split_folio(folio);
folio_unlock(folio);
folio_put(folio);
if (!err)
goto regular_folio;
return 0;
}
if (pmd_young(orig_pmd)) {
pmdp_invalidate(vma, addr, pmd);
orig_pmd = pmd_mkold(orig_pmd);
set_pmd_at(mm, addr, pmd, orig_pmd);
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
}
folio_clear_referenced(folio);
folio_test_clear_young(folio);
if (pageout) {
if (folio_isolate_lru(folio)) {
if (folio_test_unevictable(folio))
folio_putback_lru(folio);
else
list_add(&folio->lru, &folio_list);
}
} else
folio_deactivate(folio);
huge_unlock:
spin_unlock(ptl);
if (pageout)
reclaim_pages(&folio_list);
return 0;
}
regular_folio:
if (pmd_trans_unstable(pmd))
return 0;
#endif
tlb_change_page_size(tlb, PAGE_SIZE);
orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
flush_tlb_batched_pending(mm);
arch_enter_lazy_mmu_mode();
for (; addr < end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
if (pte_none(ptent))
continue;
if (!pte_present(ptent))
continue;
folio = vm_normal_folio(vma, addr, ptent);
if (!folio || folio_is_zone_device(folio))
continue;
/*
* Creating a THP page is expensive so split it only if we
* are sure it's worth. Split it if we are only owner.
*/
if (folio_test_large(folio)) {
if (folio_mapcount(folio) != 1)
break;
if (pageout_anon_only_filter && !folio_test_anon(folio))
break;
folio_get(folio);
if (!folio_trylock(folio)) {
folio_put(folio);
break;
}
pte_unmap_unlock(orig_pte, ptl);
if (split_folio(folio)) {
folio_unlock(folio);
folio_put(folio);
orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
break;
}
folio_unlock(folio);
folio_put(folio);
orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
pte--;
addr -= PAGE_SIZE;
continue;
}
/*
* Do not interfere with other mappings of this folio and
* non-LRU folio.
*/
if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
continue;
if (pageout_anon_only_filter && !folio_test_anon(folio))
continue;
VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
if (pte_young(ptent)) {
ptent = ptep_get_and_clear_full(mm, addr, pte,
tlb->fullmm);
ptent = pte_mkold(ptent);
set_pte_at(mm, addr, pte, ptent);
tlb_remove_tlb_entry(tlb, pte, addr);
}
/*
* We are deactivating a folio for accelerating reclaiming.
* VM couldn't reclaim the folio unless we clear PG_young.
* As a side effect, it makes confuse idle-page tracking
* because they will miss recent referenced history.
*/
folio_clear_referenced(folio);
folio_test_clear_young(folio);
if (pageout) {
if (folio_isolate_lru(folio)) {
if (folio_test_unevictable(folio))
folio_putback_lru(folio);
else
list_add(&folio->lru, &folio_list);
}
} else
folio_deactivate(folio);
}
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
if (pageout)
reclaim_pages(&folio_list);
cond_resched();
return 0;
}
static const struct mm_walk_ops cold_walk_ops = {
.pmd_entry = madvise_cold_or_pageout_pte_range,
};
static void madvise_cold_page_range(struct mmu_gather *tlb,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct madvise_walk_private walk_private = {
.pageout = false,
.tlb = tlb,
};
tlb_start_vma(tlb, vma);
walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
tlb_end_vma(tlb, vma);
}
static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
{
return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
}
static long madvise_cold(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start_addr, unsigned long end_addr)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_gather tlb;
*prev = vma;
if (!can_madv_lru_vma(vma))
return -EINVAL;
lru_add_drain();
tlb_gather_mmu(&tlb, mm);
madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
tlb_finish_mmu(&tlb);
return 0;
}
static void madvise_pageout_page_range(struct mmu_gather *tlb,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct madvise_walk_private walk_private = {
.pageout = true,
.tlb = tlb,
};
tlb_start_vma(tlb, vma);
walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
tlb_end_vma(tlb, vma);
}
static long madvise_pageout(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start_addr, unsigned long end_addr)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_gather tlb;
*prev = vma;
if (!can_madv_lru_vma(vma))
return -EINVAL;
/*
* If the VMA belongs to a private file mapping, there can be private
* dirty pages which can be paged out if even this process is neither
* owner nor write capable of the file. We allow private file mappings
* further to pageout dirty anon pages.
*/
if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
(vma->vm_flags & VM_MAYSHARE)))
return 0;
lru_add_drain();
tlb_gather_mmu(&tlb, mm);
madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
tlb_finish_mmu(&tlb);
return 0;
}
static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
struct mmu_gather *tlb = walk->private;
struct mm_struct *mm = tlb->mm;
struct vm_area_struct *vma = walk->vma;
spinlock_t *ptl;
pte_t *orig_pte, *pte, ptent;
struct folio *folio;
int nr_swap = 0;
unsigned long next;
next = pmd_addr_end(addr, end);
if (pmd_trans_huge(*pmd))
if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
goto next;
if (pmd_trans_unstable(pmd))
return 0;
tlb_change_page_size(tlb, PAGE_SIZE);
orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
flush_tlb_batched_pending(mm);
arch_enter_lazy_mmu_mode();
for (; addr != end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
if (pte_none(ptent))
continue;
/*
* If the pte has swp_entry, just clear page table to
* prevent swap-in which is more expensive rather than
* (page allocation + zeroing).
*/
if (!pte_present(ptent)) {
swp_entry_t entry;
entry = pte_to_swp_entry(ptent);
if (!non_swap_entry(entry)) {
nr_swap--;
free_swap_and_cache(entry);
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
} else if (is_hwpoison_entry(entry) ||
is_swapin_error_entry(entry)) {
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
}
continue;
}
folio = vm_normal_folio(vma, addr, ptent);
if (!folio || folio_is_zone_device(folio))
continue;
/*
* If pmd isn't transhuge but the folio is large and
* is owned by only this process, split it and
* deactivate all pages.
*/
if (folio_test_large(folio)) {
if (folio_mapcount(folio) != 1)
goto out;
folio_get(folio);
if (!folio_trylock(folio)) {
folio_put(folio);
goto out;
}
pte_unmap_unlock(orig_pte, ptl);
if (split_folio(folio)) {
folio_unlock(folio);
folio_put(folio);
orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
goto out;
}
folio_unlock(folio);
folio_put(folio);
orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
pte--;
addr -= PAGE_SIZE;
continue;
}
if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
if (!folio_trylock(folio))
continue;
/*
* If folio is shared with others, we mustn't clear
* the folio's dirty flag.
*/
if (folio_mapcount(folio) != 1) {
folio_unlock(folio);
continue;
}
if (folio_test_swapcache(folio) &&
!folio_free_swap(folio)) {
folio_unlock(folio);
continue;
}
folio_clear_dirty(folio);
folio_unlock(folio);
}
if (pte_young(ptent) || pte_dirty(ptent)) {
/*
* Some of architecture(ex, PPC) don't update TLB
* with set_pte_at and tlb_remove_tlb_entry so for
* the portability, remap the pte with old|clean
* after pte clearing.
*/
ptent = ptep_get_and_clear_full(mm, addr, pte,
tlb->fullmm);
ptent = pte_mkold(ptent);
ptent = pte_mkclean(ptent);
set_pte_at(mm, addr, pte, ptent);
tlb_remove_tlb_entry(tlb, pte, addr);
}
folio_mark_lazyfree(folio);
}
out:
if (nr_swap) {
if (current->mm == mm)
sync_mm_rss(mm);
add_mm_counter(mm, MM_SWAPENTS, nr_swap);
}
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
cond_resched();
next:
return 0;
}
static const struct mm_walk_ops madvise_free_walk_ops = {
.pmd_entry = madvise_free_pte_range,
};
static int madvise_free_single_vma(struct vm_area_struct *vma,
unsigned long start_addr, unsigned long end_addr)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_notifier_range range;
struct mmu_gather tlb;
/* MADV_FREE works for only anon vma at the moment */
if (!vma_is_anonymous(vma))
return -EINVAL;
range.start = max(vma->vm_start, start_addr);
if (range.start >= vma->vm_end)
return -EINVAL;
range.end = min(vma->vm_end, end_addr);
if (range.end <= vma->vm_start)
return -EINVAL;
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
range.start, range.end);
lru_add_drain();
tlb_gather_mmu(&tlb, mm);
update_hiwater_rss(mm);
mmu_notifier_invalidate_range_start(&range);
tlb_start_vma(&tlb, vma);
walk_page_range(vma->vm_mm, range.start, range.end,
&madvise_free_walk_ops, &tlb);
tlb_end_vma(&tlb, vma);
mmu_notifier_invalidate_range_end(&range);
tlb_finish_mmu(&tlb);
return 0;
}
/*
* Application no longer needs these pages. If the pages are dirty,
* it's OK to just throw them away. The app will be more careful about
* data it wants to keep. Be sure to free swap resources too. The
* zap_page_range_single call sets things up for shrink_active_list to actually
* free these pages later if no one else has touched them in the meantime,
* although we could add these pages to a global reuse list for
* shrink_active_list to pick up before reclaiming other pages.
*
* NB: This interface discards data rather than pushes it out to swap,
* as some implementations do. This has performance implications for
* applications like large transactional databases which want to discard
* pages in anonymous maps after committing to backing store the data
* that was kept in them. There is no reason to write this data out to
* the swap area if the application is discarding it.
*
* An interface that causes the system to free clean pages and flush
* dirty pages is already available as msync(MS_INVALIDATE).
*/
static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
zap_page_range_single(vma, start, end - start, NULL);
return 0;
}
static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
unsigned long start,
unsigned long *end,
int behavior)
{
if (!is_vm_hugetlb_page(vma)) {
unsigned int forbidden = VM_PFNMAP;
if (behavior != MADV_DONTNEED_LOCKED)
forbidden |= VM_LOCKED;
return !(vma->vm_flags & forbidden);
}
if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
return false;
if (start & ~huge_page_mask(hstate_vma(vma)))
return false;
/*
* Madvise callers expect the length to be rounded up to PAGE_SIZE
* boundaries, and may be unaware that this VMA uses huge pages.
* Avoid unexpected data loss by rounding down the number of
* huge pages freed.
*/
*end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
return true;
}
static long madvise_dontneed_free(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end,
int behavior)
{
struct mm_struct *mm = vma->vm_mm;
*prev = vma;
if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
return -EINVAL;
if (start == end)
return 0;
if (!userfaultfd_remove(vma, start, end)) {
*prev = NULL; /* mmap_lock has been dropped, prev is stale */
mmap_read_lock(mm);
vma = find_vma(mm, start);
if (!vma)
return -ENOMEM;
if (start < vma->vm_start) {
/*
* This "vma" under revalidation is the one
* with the lowest vma->vm_start where start
* is also < vma->vm_end. If start <
* vma->vm_start it means an hole materialized
* in the user address space within the
* virtual range passed to MADV_DONTNEED
* or MADV_FREE.
*/
return -ENOMEM;
}
/*
* Potential end adjustment for hugetlb vma is OK as
* the check below keeps end within vma.
*/
if (!madvise_dontneed_free_valid_vma(vma, start, &end,
behavior))
return -EINVAL;
if (end > vma->vm_end) {
/*
* Don't fail if end > vma->vm_end. If the old
* vma was split while the mmap_lock was
* released the effect of the concurrent
* operation may not cause madvise() to
* have an undefined result. There may be an
* adjacent next vma that we'll walk
* next. userfaultfd_remove() will generate an
* UFFD_EVENT_REMOVE repetition on the
* end-vma->vm_end range, but the manager can
* handle a repetition fine.
*/
end = vma->vm_end;
}
VM_WARN_ON(start >= end);
}
if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
return madvise_dontneed_single_vma(vma, start, end);
else if (behavior == MADV_FREE)
return madvise_free_single_vma(vma, start, end);
else
return -EINVAL;
}
static long madvise_populate(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end,
int behavior)
{
const bool write = behavior == MADV_POPULATE_WRITE;
struct mm_struct *mm = vma->vm_mm;
unsigned long tmp_end;
int locked = 1;
long pages;
*prev = vma;
while (start < end) {
/*
* We might have temporarily dropped the lock. For example,
* our VMA might have been split.
*/
if (!vma || start >= vma->vm_end) {
vma = vma_lookup(mm, start);
if (!vma)
return -ENOMEM;
}
tmp_end = min_t(unsigned long, end, vma->vm_end);
/* Populate (prefault) page tables readable/writable. */
pages = faultin_vma_page_range(vma, start, tmp_end, write,
&locked);
if (!locked) {
mmap_read_lock(mm);
locked = 1;
*prev = NULL;
vma = NULL;
}
if (pages < 0) {
switch (pages) {
case -EINTR:
return -EINTR;
case -EINVAL: /* Incompatible mappings / permissions. */
return -EINVAL;
case -EHWPOISON:
return -EHWPOISON;
case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
return -EFAULT;
default:
pr_warn_once("%s: unhandled return value: %ld\n",
__func__, pages);
fallthrough;
case -ENOMEM:
return -ENOMEM;
}
}
start += pages * PAGE_SIZE;
}
return 0;
}
/*
* Application wants to free up the pages and associated backing store.
* This is effectively punching a hole into the middle of a file.
*/
static long madvise_remove(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end)
{
loff_t offset;
int error;
struct file *f;
struct mm_struct *mm = vma->vm_mm;
*prev = NULL; /* tell sys_madvise we drop mmap_lock */
if (vma->vm_flags & VM_LOCKED)
return -EINVAL;
f = vma->vm_file;
if (!f || !f->f_mapping || !f->f_mapping->host) {
return -EINVAL;
}
if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
return -EACCES;
offset = (loff_t)(start - vma->vm_start)
+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
/*
* Filesystem's fallocate may need to take i_rwsem. We need to
* explicitly grab a reference because the vma (and hence the
* vma's reference to the file) can go away as soon as we drop
* mmap_lock.
*/
get_file(f);
if (userfaultfd_remove(vma, start, end)) {
/* mmap_lock was not released by userfaultfd_remove() */
mmap_read_unlock(mm);
}
error = vfs_fallocate(f,
FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
offset, end - start);
fput(f);
mmap_read_lock(mm);
return error;
}
/*
* Apply an madvise behavior to a region of a vma. madvise_update_vma
* will handle splitting a vm area into separate areas, each area with its own
* behavior.
*/
static int madvise_vma_behavior(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end,
unsigned long behavior)
{
int error;
struct anon_vma_name *anon_name;
unsigned long new_flags = vma->vm_flags;
switch (behavior) {
case MADV_REMOVE:
return madvise_remove(vma, prev, start, end);
case MADV_WILLNEED:
return madvise_willneed(vma, prev, start, end);
case MADV_COLD:
return madvise_cold(vma, prev, start, end);
case MADV_PAGEOUT:
return madvise_pageout(vma, prev, start, end);
case MADV_FREE:
case MADV_DONTNEED:
case MADV_DONTNEED_LOCKED:
return madvise_dontneed_free(vma, prev, start, end, behavior);
case MADV_POPULATE_READ:
case MADV_POPULATE_WRITE:
return madvise_populate(vma, prev, start, end, behavior);
case MADV_NORMAL:
new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
break;
case MADV_SEQUENTIAL:
new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
break;
case MADV_RANDOM:
new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
break;
case MADV_DONTFORK:
new_flags |= VM_DONTCOPY;
break;
case MADV_DOFORK:
if (vma->vm_flags & VM_IO)
return -EINVAL;
new_flags &= ~VM_DONTCOPY;
break;
case MADV_WIPEONFORK:
/* MADV_WIPEONFORK is only supported on anonymous memory. */
if (vma->vm_file || vma->vm_flags & VM_SHARED)
return -EINVAL;
new_flags |= VM_WIPEONFORK;
break;
case MADV_KEEPONFORK:
new_flags &= ~VM_WIPEONFORK;
break;
case MADV_DONTDUMP:
new_flags |= VM_DONTDUMP;
break;
case MADV_DODUMP:
if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
return -EINVAL;
new_flags &= ~VM_DONTDUMP;
break;
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
error = ksm_madvise(vma, start, end, behavior, &new_flags);
if (error)
goto out;
break;
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
error = hugepage_madvise(vma, &new_flags, behavior);
if (error)
goto out;
break;
case MADV_COLLAPSE:
return madvise_collapse(vma, prev, start, end);
}
anon_name = anon_vma_name(vma);
anon_vma_name_get(anon_name);
error = madvise_update_vma(vma, prev, start, end, new_flags,
anon_name);
anon_vma_name_put(anon_name);
out:
/*
* madvise() returns EAGAIN if kernel resources, such as
* slab, are temporarily unavailable.
*/
if (error == -ENOMEM)
error = -EAGAIN;
return error;
}
#ifdef CONFIG_MEMORY_FAILURE
/*
* Error injection support for memory error handling.
*/
static int madvise_inject_error(int behavior,
unsigned long start, unsigned long end)
{
unsigned long size;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
for (; start < end; start += size) {
unsigned long pfn;
struct page *page;
int ret;
ret = get_user_pages_fast(start, 1, 0, &page);
if (ret != 1)
return ret;
pfn = page_to_pfn(page);
/*
* When soft offlining hugepages, after migrating the page
* we dissolve it, therefore in the second loop "page" will
* no longer be a compound page.
*/
size = page_size(compound_head(page));
if (behavior == MADV_SOFT_OFFLINE) {
pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
pfn, start);
ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
} else {
pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
pfn, start);
ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
if (ret == -EOPNOTSUPP)
ret = 0;
}
if (ret)
return ret;
}
return 0;
}
#endif
static bool
madvise_behavior_valid(int behavior)
{
switch (behavior) {
case MADV_DOFORK:
case MADV_DONTFORK:
case MADV_NORMAL:
case MADV_SEQUENTIAL:
case MADV_RANDOM:
case MADV_REMOVE:
case MADV_WILLNEED:
case MADV_DONTNEED:
case MADV_DONTNEED_LOCKED:
case MADV_FREE:
case MADV_COLD:
case MADV_PAGEOUT:
case MADV_POPULATE_READ:
case MADV_POPULATE_WRITE:
#ifdef CONFIG_KSM
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
#endif
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
case MADV_COLLAPSE:
#endif
case MADV_DONTDUMP:
case MADV_DODUMP:
case MADV_WIPEONFORK:
case MADV_KEEPONFORK:
#ifdef CONFIG_MEMORY_FAILURE
case MADV_SOFT_OFFLINE:
case MADV_HWPOISON:
#endif
return true;
default:
return false;
}
}
static bool process_madvise_behavior_valid(int behavior)
{
switch (behavior) {
case MADV_COLD:
case MADV_PAGEOUT:
case MADV_WILLNEED:
case MADV_COLLAPSE:
return true;
default:
return false;
}
}
/*
* Walk the vmas in range [start,end), and call the visit function on each one.
* The visit function will get start and end parameters that cover the overlap
* between the current vma and the original range. Any unmapped regions in the
* original range will result in this function returning -ENOMEM while still
* calling the visit function on all of the existing vmas in the range.
* Must be called with the mmap_lock held for reading or writing.
*/
static
int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long arg,
int (*visit)(struct vm_area_struct *vma,
struct vm_area_struct **prev, unsigned long start,
unsigned long end, unsigned long arg))
{
struct vm_area_struct *vma;
struct vm_area_struct *prev;
unsigned long tmp;
int unmapped_error = 0;
/*
* If the interval [start,end) covers some unmapped address
* ranges, just ignore them, but return -ENOMEM at the end.
* - different from the way of handling in mlock etc.
*/
vma = find_vma_prev(mm, start, &prev);
if (vma && start > vma->vm_start)
prev = vma;
for (;;) {
int error;
/* Still start < end. */
if (!vma)
return -ENOMEM;
/* Here start < (end|vma->vm_end). */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
if (start >= end)
break;
}
/* Here vma->vm_start <= start < (end|vma->vm_end) */
tmp = vma->vm_end;
if (end < tmp)
tmp = end;
/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
error = visit(vma, &prev, start, tmp, arg);
if (error)
return error;
start = tmp;
if (prev && start < prev->vm_end)
start = prev->vm_end;
if (start >= end)
break;
if (prev)
vma = find_vma(mm, prev->vm_end);
else /* madvise_remove dropped mmap_lock */
vma = find_vma(mm, start);
}
return unmapped_error;
}
#ifdef CONFIG_ANON_VMA_NAME
static int madvise_vma_anon_name(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end,
unsigned long anon_name)
{
int error;
/* Only anonymous mappings can be named */
if (vma->vm_file && !vma_is_anon_shmem(vma))
return -EBADF;
error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
(struct anon_vma_name *)anon_name);
/*
* madvise() returns EAGAIN if kernel resources, such as
* slab, are temporarily unavailable.
*/
if (error == -ENOMEM)
error = -EAGAIN;
return error;
}
int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
unsigned long len_in, struct anon_vma_name *anon_name)
{
unsigned long end;
unsigned long len;
if (start & ~PAGE_MASK)
return -EINVAL;
len = (len_in + ~PAGE_MASK) & PAGE_MASK;
/* Check to see whether len was rounded up from small -ve to zero */
if (len_in && !len)
return -EINVAL;
end = start + len;
if (end < start)
return -EINVAL;
if (end == start)
return 0;
return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
madvise_vma_anon_name);
}
#endif /* CONFIG_ANON_VMA_NAME */
/*
* The madvise(2) system call.
*
* Applications can use madvise() to advise the kernel how it should
* handle paging I/O in this VM area. The idea is to help the kernel
* use appropriate read-ahead and caching techniques. The information
* provided is advisory only, and can be safely disregarded by the
* kernel without affecting the correct operation of the application.
*
* behavior values:
* MADV_NORMAL - the default behavior is to read clusters. This
* results in some read-ahead and read-behind.
* MADV_RANDOM - the system should read the minimum amount of data
* on any access, since it is unlikely that the appli-
* cation will need more than what it asks for.
* MADV_SEQUENTIAL - pages in the given range will probably be accessed
* once, so they can be aggressively read ahead, and
* can be freed soon after they are accessed.
* MADV_WILLNEED - the application is notifying the system to read
* some pages ahead.
* MADV_DONTNEED - the application is finished with the given range,
* so the kernel can free resources associated with it.
* MADV_FREE - the application marks pages in the given range as lazy free,
* where actual purges are postponed until memory pressure happens.
* MADV_REMOVE - the application wants to free up the given range of
* pages and associated backing store.
* MADV_DONTFORK - omit this area from child's address space when forking:
* typically, to avoid COWing pages pinned by get_user_pages().
* MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
* MADV_WIPEONFORK - present the child process with zero-filled memory in this
* range after a fork.
* MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
* MADV_HWPOISON - trigger memory error handler as if the given memory range
* were corrupted by unrecoverable hardware memory failure.
* MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
* MADV_MERGEABLE - the application recommends that KSM try to merge pages in
* this area with pages of identical content from other such areas.
* MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
* MADV_HUGEPAGE - the application wants to back the given range by transparent
* huge pages in the future. Existing pages might be coalesced and
* new pages might be allocated as THP.
* MADV_NOHUGEPAGE - mark the given range as not worth being backed by
* transparent huge pages so the existing pages will not be
* coalesced into THP and new pages will not be allocated as THP.
* MADV_COLLAPSE - synchronously coalesce pages into new THP.
* MADV_DONTDUMP - the application wants to prevent pages in the given range
* from being included in its core dump.
* MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
* MADV_COLD - the application is not expected to use this memory soon,
* deactivate pages in this range so that they can be reclaimed
* easily if memory pressure happens.
* MADV_PAGEOUT - the application is not expected to use this memory soon,
* page out the pages in this range immediately.
* MADV_POPULATE_READ - populate (prefault) page tables readable by
* triggering read faults if required
* MADV_POPULATE_WRITE - populate (prefault) page tables writable by
* triggering write faults if required
*
* return values:
* zero - success
* -EINVAL - start + len < 0, start is not page-aligned,
* "behavior" is not a valid value, or application
* is attempting to release locked or shared pages,
* or the specified address range includes file, Huge TLB,
* MAP_SHARED or VMPFNMAP range.
* -ENOMEM - addresses in the specified range are not currently
* mapped, or are outside the AS of the process.
* -EIO - an I/O error occurred while paging in data.
* -EBADF - map exists, but area maps something that isn't a file.
* -EAGAIN - a kernel resource was temporarily unavailable.
*/
int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
{
unsigned long end;
int error;
int write;
size_t len;
struct blk_plug plug;
start = untagged_addr(start);
if (!madvise_behavior_valid(behavior))
return -EINVAL;
if (!PAGE_ALIGNED(start))
return -EINVAL;
len = PAGE_ALIGN(len_in);
/* Check to see whether len was rounded up from small -ve to zero */
if (len_in && !len)
return -EINVAL;
end = start + len;
if (end < start)
return -EINVAL;
if (end == start)
return 0;
#ifdef CONFIG_MEMORY_FAILURE
if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
return madvise_inject_error(behavior, start, start + len_in);
#endif
write = madvise_need_mmap_write(behavior);
if (write) {
if (mmap_write_lock_killable(mm))
return -EINTR;
} else {
mmap_read_lock(mm);
}
blk_start_plug(&plug);
error = madvise_walk_vmas(mm, start, end, behavior,
madvise_vma_behavior);
blk_finish_plug(&plug);
if (write)
mmap_write_unlock(mm);
else
mmap_read_unlock(mm);
return error;
}
SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
{
return do_madvise(current->mm, start, len_in, behavior);
}
SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
size_t, vlen, int, behavior, unsigned int, flags)
{
ssize_t ret;
struct iovec iovstack[UIO_FASTIOV], iovec;
struct iovec *iov = iovstack;
struct iov_iter iter;
struct task_struct *task;
struct mm_struct *mm;
size_t total_len;
unsigned int f_flags;
if (flags != 0) {
ret = -EINVAL;
goto out;
}
ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
if (ret < 0)
goto out;
task = pidfd_get_task(pidfd, &f_flags);
if (IS_ERR(task)) {
ret = PTR_ERR(task);
goto free_iov;
}
if (!process_madvise_behavior_valid(behavior)) {
ret = -EINVAL;
goto release_task;
}
/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
if (IS_ERR_OR_NULL(mm)) {
ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
goto release_task;
}
/*
* Require CAP_SYS_NICE for influencing process performance. Note that
* only non-destructive hints are currently supported.
*/
if (!capable(CAP_SYS_NICE)) {
ret = -EPERM;
goto release_mm;
}
total_len = iov_iter_count(&iter);
while (iov_iter_count(&iter)) {
iovec = iov_iter_iovec(&iter);
ret = do_madvise(mm, (unsigned long)iovec.iov_base,
iovec.iov_len, behavior);
if (ret < 0)
break;
iov_iter_advance(&iter, iovec.iov_len);
}
ret = (total_len - iov_iter_count(&iter)) ? : ret;
release_mm:
mmput(mm);
release_task:
put_task_struct(task);
free_iov:
kfree(iov);
out:
return ret;
}
SYSCALL_DEFINE3(pmadv_ksm, int, pidfd, int, behaviour, unsigned int, flags)
{
#ifdef CONFIG_KSM
ssize_t ret;
struct pid *pid;
struct task_struct *task;
struct mm_struct *mm;
unsigned int f_flags;
struct vm_area_struct *vma;
struct vma_iterator vmi;
if (flags != 0) {
ret = -EINVAL;
goto out;
}
switch (behaviour) {
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
break;
default:
ret = -EINVAL;
goto out;
break;
}
pid = pidfd_get_pid(pidfd, &f_flags);
if (IS_ERR(pid)) {
ret = PTR_ERR(pid);
goto out;
}
task = get_pid_task(pid, PIDTYPE_PID);
if (!task) {
ret = -ESRCH;
goto put_pid;
}
/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
if (IS_ERR_OR_NULL(mm)) {
ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
goto release_task;
}
/* Require CAP_SYS_NICE for influencing process performance. */
if (!capable(CAP_SYS_NICE)) {
ret = -EPERM;
goto release_mm;
}
if (mmap_write_lock_killable(mm)) {
ret = -EINTR;
goto release_mm;
}
vma_iter_init(&vmi, mm, 0);
for_each_vma(vmi, vma) {
switch (behaviour) {
case MADV_MERGEABLE:
ret = ksm_madvise_merge(vma->vm_mm, vma, &vma->vm_flags);
if (!ret)
vm_flags_set(vma, VM_MERGEABLE);
break;
case MADV_UNMERGEABLE:
ret = ksm_madvise_unmerge(vma, vma->vm_start, vma->vm_end, &vma->vm_flags);
if (!ret)
vm_flags_clear(vma, VM_MERGEABLE);
break;
default:
/* look, ma, no brain */
break;
}
if (ret)
break;
}
mmap_write_unlock(mm);
release_mm:
mmput(mm);
release_task:
put_task_struct(task);
put_pid:
put_pid(pid);
out:
return ret;
#else /* CONFIG_KSM */
return -ENOSYS;
#endif /* CONFIG_KSM */
}
#ifdef CONFIG_KSM
static ssize_t ksm_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%u\n", __NR_pmadv_ksm);
}
static struct kobj_attribute pmadv_ksm_attr = __ATTR_RO(ksm);
static struct attribute *pmadv_sysfs_attrs[] = {
&pmadv_ksm_attr.attr,
NULL,
};
static const struct attribute_group pmadv_sysfs_attr_group = {
.attrs = pmadv_sysfs_attrs,
.name = "pmadv",
};
static int __init pmadv_sysfs_init(void)
{
return sysfs_create_group(kernel_kobj, &pmadv_sysfs_attr_group);
}
subsys_initcall(pmadv_sysfs_init);
#endif /* CONFIG_KSM */
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