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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 6/8] mm/khugepaged: unmap pte before releasing vma write lock Date: Mon, 6 Jul 2026 09:44:53 -0600 Message-ID: <20260706154500.39178-7-npache@redhat.com> In-Reply-To: <20260706154500.39178-1-npache@redhat.com> References: <20260706154500.39178-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: 1HsCJASuIBOSiAQ5dogkAAbu22r7dtYicM77RXT2crQ_1783352705 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Stat-Signature: aqpzae9d31mb7aqf3yfqc1xi4knay1t9 X-Rspamd-Queue-Id: 86FFA4000E X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783352714-887873 X-HE-Meta: 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 nwKbgc7N pGRzxLRwTLh8Zp6jZhPCkOcysG0uBl4EX8GhM1IPV53jd1894EJcgkZ9ySytD9QAA3KADo3YCFRIiACZyX4XptyRwNLunb3SSupDsc2adSHz6J0dDjKGlV+1qRpichIdNGN7uvPB6+ZbaNk+r1IkkcP1rAKzlchKp2v3kRymE7qdamh5cp8N0Q5jyctrcvrVjwiQHOORNOi4pguYVyp/kt7xfaHy9pKRn/HEA2QuRU866H8Q/wBtJ7VWOKQG3Nl/qYb5G/zVYAt7uhTkwgaaUzTEJ6n4/jh4UAuuNjp+6IGWYUViTOUy4HypEDr7m9W9/tAbzM2ijBoEsudMKshNyBxC8fL3HFrWYTYnb994G2X3r53M= 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 c4ea2dc1591b..3c6f1254deca 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1548,10 +1548,10 @@ 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