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mm/rmap: use page_move_anon_rmap() when reusing a mapped PageAnon() page exclusively

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We want to mark anonymous pages exclusive, and when using
page_move_anon_rmap() we know that we are the exclusive user, as properly
documented.  This is a preparation for marking anonymous pages exclusive
in page_move_anon_rmap().

In both instances, we're holding page lock and are sure that we're the
exclusive owner (page_count() == 1).  hugetlb already properly uses
page_move_anon_rmap() in the write fault handler.

Note that in case of a PTE-mapped THP, we'll only end up calling this
function if the whole THP is only referenced by the single PTE mapping a
single subpage (page_count() == 1); consequently, it's fine to modify the
compound page mapping inside page_move_anon_rmap().

Link: https://lkml.kernel.org/r/20220428083441.37290-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-05-09 18:20:43 -07:00 committed by akpm
parent 40f2bbf711
commit 6c54dc6c74
2 changed files with 3 additions and 0 deletions
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2
mm/huge_memory.c
View File

@ -1317,6 +1317,8 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
try_to_free_swap(page);
if (page_count(page) == 1) {
pmd_t entry;
page_move_anon_rmap(page, vma);
entry = pmd_mkyoung(orig_pmd);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))

1
mm/memory.c
View File

@ -3303,6 +3303,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
* and the page is locked, it's dark out, and we're wearing
* sunglasses. Hit it.
*/
page_move_anon_rmap(page, vma);
unlock_page(page);
wp_page_reuse(vmf);
return VM_FAULT_WRITE;