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authorLorenzo Stoakes <lstoakes@gmail.com>2023-05-06 17:05:25 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-06-10 02:25:17 +0300
commit311150343e69ed4fe6380d2de74602a2a29df7c2 (patch)
tree08380fe1b648b560ce4287fac019d6b70a4fa266 /mm/gup.c
parent9f297db35667021925b67e27d81463e38445041c (diff)
downloadlinux-311150343e69ed4fe6380d2de74602a2a29df7c2.tar.xz
mm/gup: add missing gup_must_unshare() check to gup_huge_pgd()
All other instances of gup_huge_pXd() perform the unshare check, so update the PGD-specific function to do so as well. While checking pgd_write() might seem unusual, this function already performs such a check via pgd_access_permitted() so this is in line with the existing implementation. David said: : This change makes unshare handling across all GUP-fast variants : consistent, which is desirable as GUP-fast is complicated enough : already even when consistent. : : This function was the only one I seemed to have missed (or left out and : forgot why -- maybe because it's really dead code for now). The COW : selftest would identify the problem, so far there was no report. : Either the selftest wasn't run on corresponding architectures with that : hugetlb size, or that code is still dead code and unused by : architectures. : : the original commit(s) that added unsharing explain why we care about : these checks: : : a7f226604170acd6 ("mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page") : 84209e87c6963f92 ("mm/gup: reliable R/O long-term pinning in COW mappings") Link: https://lkml.kernel.org/r/cb971ac8dd315df97058ea69442ecc007b9a364a.1683381545.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> Suggested-by: David Hildenbrand <david@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index bbe416236593..e19b06a66229 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2755,6 +2755,11 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
return 0;
}
+ if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) {
+ gup_put_folio(folio, refs, flags);
+ return 0;
+ }
+
*nr += refs;
folio_set_referenced(folio);
return 1;