The patch titled
Subject: mm/swapfile: fix lost swap bits in unuse_pte()
has been added to the -mm mm-unstable branch. Its filename is
mm-swapfile-fix-lost-swap-bits-in-unuse_pte.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swapfile-fix-lost-swap-bits-in-unuse_pte.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/swapfile: fix lost swap bits in unuse_pte()
Date: Thu, 19 May 2022 20:50:27 +0800
This is observed by code review only but not any real report.
When we turn off swapping we could have lost the bits stored in the swap
ptes. The new rmap-exclusive bit is fine since that turned into a page
flag, but not for soft-dirty and uffd-wp. Add them.
Link: https://lkml.kernel.org/r/20220519125030.21486-3-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Suggested-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/mm/swapfile.c~mm-swapfile-fix-lost-swap-bits-in-unuse_pte
+++ a/mm/swapfile.c
@@ -1774,7 +1774,7 @@ static int unuse_pte(struct vm_area_stru
{
struct page *swapcache;
spinlock_t *ptl;
- pte_t *pte;
+ pte_t *pte, new_pte;
int ret = 1;
swapcache = page;
@@ -1823,8 +1823,12 @@ static int unuse_pte(struct vm_area_stru
page_add_new_anon_rmap(page, vma, addr);
lru_cache_add_inactive_or_unevictable(page, vma);
}
- set_pte_at(vma->vm_mm, addr, pte,
- pte_mkold(mk_pte(page, vma->vm_page_prot)));
+ new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
+ if (pte_swp_soft_dirty(*pte))
+ new_pte = pte_mksoft_dirty(new_pte);
+ if (pte_swp_uffd_wp(*pte))
+ new_pte = pte_mkuffd_wp(new_pte);
+ set_pte_at(vma->vm_mm, addr, pte, new_pte);
swap_free(entry);
out:
pte_unmap_unlock(pte, ptl);
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-z3fold-fix-sheduling-while-atomic.patch
mm-z3fold-fix-possible-null-pointer-dereferencing.patch
mm-z3fold-remove-buggy-use-of-stale-list-for-allocation.patch
mm-z3fold-throw-warning-on-failure-of-trylock_page-in-z3fold_alloc.patch
revert-mm-z3foldc-allow-__gfp_highmem-in-z3fold_alloc.patch
mm-z3fold-put-z3fold-page-back-into-unbuddied-list-when-reclaim-or-migration-fails.patch
mm-z3fold-always-clear-page_claimed-under-z3fold-page-lock.patch
mm-z3fold-fix-z3fold_reclaim_page-races-with-z3fold_free.patch
mm-z3fold-fix-z3fold_page_migrate-races-with-z3fold_map.patch
mm-swap-use-helper-is_swap_pte-in-swap_vma_readahead.patch
mm-swap-use-helper-macro-__attr_rw.patch
mm-swap-fold-__swap_info_get-into-its-sole-caller.patch
mm-swap-remove-unneeded-return-value-of-free_swap_slot.patch
mm-swap-print-bad-swap-offset-entry-in-get_swap_device.patch
mm-swap-remove-buggy-cache-nr-check-in-refill_swap_slots_cache.patch
mm-swap-remove-unneeded-p-=-null-check-in-__swap_duplicate.patch
mm-swap-make-page_swapcount-and-__lru_add_drain_all.patch
mm-swap-avoid-calling-swp_swap_info-when-try-to-check-swp_stable_writes.patch
mm-swap-add-helper-swap_offset_available.patch
mm-swap-fix-the-obsolete-comment-for-swp_type_shift.patch
mm-swap-clean-up-the-comment-of-find_next_to_unuse.patch
mm-swap-fix-the-comment-of-get_kernel_pages.patch
mm-swap-fix-comment-about-swap-extent.patch
mm-swapfile-unuse_pte-can-map-random-data-if-swap-read-fails.patch
mm-swapfile-fix-lost-swap-bits-in-unuse_pte.patch
mm-madvise-free-hwpoison-and-swapin-error-entry-in-madvise_free_pte_range.patch
mm-shmem-fix-infinite-loop-when-swap-in-shmem-error-at-swapoff-time.patch
mm-filter-out-swapin-error-entry-in-shmem-mapping.patch
