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Code Issues Releases Wiki Activity

mm/swapfile: fix lost swap bits in unuse_pte() 

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@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-05-19 20:50:27 +08:00 committed by akpm
parent 9f186f9e5f
commit 14a762dd19
1 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
mm/swapfile.c
View File

@ -1774,7 +1774,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
{
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_struct *vma, pmd_t *pmd,
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);