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Howlett" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , "Kees Cook" , "Peter Zijlstra" , "Jann Horn" , "Pedro Falcato" , "Hugh Dickins" , "Pasha Tatashin" , "Pratyush Yadav" , "Matthew Wilcox (Oracle)" , "Jan Kara" , "Lance Yang" , "Rik van Riel" , "Harry Yoo" , "Alistair Popple" , "Nico Pache" , "Ryan Roberts" , "Dev Jain" , "Usama Arif" , "Kiryl Shutsemau" , "Matthew Brost" , "John Hubbard" , "Peter Xu" , "Will Deacon" , "Aneesh Kumar K.V" , "Nick Piggin" , "Oscar Salvador" , "Minchan Kim" , "Muchun Song" , "Xu Xin" , "Chengming Zhou" , "Chris Li" , "Kemeng Shi" , "Nhat Pham" , "Youngjun Park" , "Gregory Price" , "Joshua Hahn" , "Rakie Kim" , "Ying Huang" , "Jason Gunthorpe" From: "Zi Yan" X-Mailer: aerc 0.22.0 References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-13-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-13-6f74bec9a5bb@kernel.org> X-ClientProxiedBy: YQBPR0101CA0165.CANPRD01.PROD.OUTLOOK.COM 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon Oct 26, 2026 at 7:17 PM EDT, David Hildenbrand (Arm) wrote: > From: Chris Mason > > zap_huge_pmd_folio() removes the rmap before calling folio_mark_dirty(). > If this was the last mapping, truncation can skip unmapping the folio > and proceed without waiting for the PMD lock, racing with dirtying. > > ifs_set_range_dirty() can oops if MADV_DONTNEED races with > ftruncate() on XFS, when we get the folio set dirty after it was found > to not be mapped anymore. > > Move folio_mark_dirty() and folio_mark_accessed() before rmap removal, > matching the PTE zap path. This keeps the folio mapped while updating > its state, so truncation must wait for the page table lock. > > Fix generated by an LLM and sent by Chris Mason in private. > > Fixes: fe6cf984939d ("mm/huge_memory: transfer the pmd dirty bit to the f= olio on zap") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > [ david: simplify comment and description ] > Signed-off-by: David Hildenbrand (Arm) > --- > mm/huge_memory.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > It seems to me that moving the rmap removal code after folio_mark_*() matches zap_present_folio_ptes() closer. Feel free to use it or ignore it. Anyway, Reviewed-by: Zi Yan diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bd44d58e86845..192f7969e3648 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2484,10 +2484,6 @@ static void zap_huge_pmd_folio(struct mm_struct *mm,= struct vm_area_struct *vma, { const bool is_device_private =3D folio_is_device_private(folio); =20 - /* Present and device private folios are rmappable. */ - if (is_present || is_device_private) - folio_remove_rmap_pmd(folio, &folio->page, vma); - if (folio_test_anon(folio)) { add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); } else { @@ -2501,6 +2497,13 @@ static void zap_huge_pmd_folio(struct mm_struct *mm,= struct vm_area_struct *vma, folio_mark_accessed(folio); } =20 + /* + * Present and device private folios are rmappable. Only remove the rmap + * after transferring young+dirty to the folio. + */ + if (is_present || is_device_private) + folio_remove_rmap_pmd(folio, &folio->page, vma); + /* Device private folios are pinned. */ if (is_device_private) folio_put(folio); --=20 Best Regards, Yan, Zi