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Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan Subject: [PATCH v2 6/7] mm/khugepaged: unmap pte before releasing vma write lock Date: Tue, 14 Jul 2026 20:59:35 -0600 Message-ID: <20260715025941.1571316-7-npache@redhat.com> In-Reply-To: <20260715025941.1571316-1-npache@redhat.com> References: <20260715025941.1571316-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: dnInRDNJ3GTx1SxDVvfK8cUK0gx5RNokDiAtUI0y8Ro_1784084469 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Queue-Id: E4AF8180003 X-Rspam-User: X-Stat-Signature: 5ubqopn3t5gjo6wq6ihkout8jgtkw7of X-Rspamd-Server: rspam03 X-HE-Tag: 1784084478-575501 X-HE-Meta: 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 wxDrpz/e p1+hs/vGJk7qG7VsWlP3iDxEJHTkXZkAYIlmD75413sNTiAE9/CO7y1dWPwi0u2HhUB4IvKwaY7AoBeVtgScnTidMWsscn/NXwS0c0H61ItljaunZGDBCbEWxy5Tk/quLYpqv9p65S3/O55RC1CFgvNv2cYe60OTjU87mFIsoYAQD+ZoUUqlssVQYLZna3Y4421EnfReFsCnEy7GEP+P6y/MrCPQ5lr5B7twY+1FoiJv053cdR1KAr5a99iBkAit0tKJkH6jXfNrmi/e/EUSGXw16qGOxK9LVSrQ5DP402z4/uWLHRMz4pwWtXEkgbgOKiLrmGsFkM5dT5nkSwiXcJXmhv4OUBrj9KbAGhseSUb8RZtE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: We are currently dropping the anon_vma write lock before unmapping the PTE. Although this is safe, due to us still holding the mmap_write_lock, its safer and less confusing to switch the order of these two operations. Suggested-by: David Hildenbrand Signed-off-by: Nico Pache --- mm/khugepaged.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 655dbc90535a..40125dcb4de9 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1546,10 +1546,10 @@ static enum scan_result collapse_huge_page(struct mm_struct *mm, unsigned long s result = SCAN_SUCCEED; out_up_write: - if (anon_vma_locked) - anon_vma_unlock_write(vma->anon_vma); if (pte) pte_unmap(pte); + if (anon_vma_locked) + anon_vma_unlock_write(vma->anon_vma); mmap_write_unlock(mm); out_nolock: if (folio) -- 2.54.0