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smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; arc=none smtp.remote-ip=91.218.175.197 Received: from mta0.migadu.com (out-197.mta0.migadu.com [91.218.175.197]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 18B25606A326 for ; Mon, 2 Nov 2026 04:58:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 18B25606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev X-Envelope-To: stable@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=VjEa8aUzoMl3SYNFpAhF7zUKPZ6wHLLQaYP9asa0BH0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793595483; v=1; x=1794200283; b=Hd5/4EfZTqDJhoJQj3RsxtDVnqKy1aamG9WHQGlhuYDbiUFMRMuVUh4U5WZxWeDr/5mCNBgn FHjhJk19Z2BSSg+yJ71g766NnsgHdRSQLGkOUEsKwe+DVjg5v3ia4eonJn1QqSAdzJyZEe1pud3 zdEAiA5fQmMfolu9HsRAjM9w= X-Envelope-To: stable@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 36faa33dfd74c51c; 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-Mailing-List: stable@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 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