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Mon, 02 Nov 2026 04:58:02 +0000 X-Mizu-Trace-ID: 36faa33dfd74c51c 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, josef@toxicpanda.com, stable@vger.kernel.org, usama.anjum@arm.com Subject: Re: [PATCH v3 15/47] mm/khugepaged: always recheck the pmd in try_collapse_pte_mapped_thp() Date: Mon, 2 Nov 2026 12:57:53 +0800 Message-ID: <20261102045753.34901-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261031-fixes_core-v3-15-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-15-d6437171ecc3@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 310FD120002 X-Stat-Signature: nxwscgwwjfy3x1es8xojgd8mhshrmaz7 X-Rspamd-Server: rspam01 X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793595485-936898 X-HE-Meta: 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 vK3enKX3 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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 Sat, Oct 31, 2026 at 10:39:44AM +0100, David Hildenbrand (Arm) wrote: >From: Josef Bacik > >try_collapse_pte_mapped_thp() drops the PTE lock after it has cleared the >page table, and takes the PMD lock and the PTE lock to remove it. > >In between, MADV_DONTNEED with CONFIG_PT_RECLAIM can reclaim the >page table. The pmd_same() check is supposed to handle this, but it is >only done with CONFIG_SPLIT_PTE_PTLOCKS. > >Fix it by performing the check unconditionally. > >Fix generated by an LLM and sent by Josef Bacik in private. > >Fixes: 6375e95f381e ("mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED)") >Cc: stable@vger.kernel.org >Signed-off-by: Josef Bacik >[ david: adjust description ] >Reviewed-by: Gregory Price (Meta) >Tested-by: Gregory Price (Meta) >Tested-by: Muhammad Usama Anjum >Signed-off-by: David Hildenbrand (Arm) >--- Nothing jumped out at me, so: Reviewed-by: Lance Yang