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bh=tTZpPE9gJn7s96098K7j6uvB27YaMf32yiUhWF9ATX4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793202859; v=1; x=1793807659; b=bIPJgOc3iPcKTa1DXojN+YH2KEJcCalwAlquT1K3q2vP78rezERhjcEiyPnYf3XJJi+zm40e VZ8Y7h0Sg0LHwZ3RIB6hSZlxVJqtHyTLtmTMwa/Q5NiV5ZlDRHprLtwNr+zvun7UOnbjrZLyZOI 1EXHQla+Wo0nAnoYaUtKJ62U= X-Envelope-To: linux-arch@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id f81f3d53b1ebb019; Wed, 28 Oct 2026 15:54:18 +0000 X-Mizu-Trace-ID: f81f3d53b1ebb019 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: david@kernel.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, ljs@kernel.org, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kees@kernel.org, peterz@infradead.org, jannh@google.com, pfalcato@suse.de, hughd@google.com, pasha.tatashin@soleen.com, pratyush@kernel.org, willy@infradead.org, jack@suse.cz, ziy@nvidia.com, lance.yang@linux.dev, riel@surriel.com, harry@kernel.org, apopple@nvidia.com, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, usama.arif@linux.dev, kas@kernel.org, matthew.brost@intel.com, jhubbard@nvidia.com, peterx@redhat.com, will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, osalvador@suse.de, minchan@kernel.org, muchun.song@linux.dev, xu.xin@linux.dev, chengming.zhou@linux.dev, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, youngjun.park@lge.com, gourry@gourry.net, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, jgg@ziepe.ca, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, mason@kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 13/46] mm/huge_memory: fix truncate racing with PMD zapping Date: Wed, 28 Oct 2026 23:54:11 +0800 Message-ID: <20261028155411.50458-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261027-fixes_core-v1-13-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-13-6f74bec9a5bb@kernel.org> X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Tue, Oct 27, 2026 at 12:17:33AM +0100, 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 folio on zap") >Cc: stable@vger.kernel.org >Signed-off-by: Chris Mason >[ david: simplify comment and description ] >Signed-off-by: David Hildenbrand (Arm) >--- Good catch! Reviewed-by: Lance Yang