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Tue, 27 Oct 2026 11:04:01 -0700 (PDT) Received: from [10.206.51.58] ([129.236.225.183]) by smtp.gmail.com with ESMTPSA id af79cd13be357-940f0a94a5csm1037624685a.41.2026.10.27.11.03.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Oct 2026 11:04:00 -0700 (PDT) Message-ID: <208738b1-35df-458c-9955-e2e5318fd2c7@columbia.edu> Date: Tue, 27 Oct 2026 14:03:58 -0400 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/46] mm/huge_memory: fix list corruption when deferred_split_scan() races with deferred_split_folio() To: "David Hildenbrand (Arm)" , Johannes Weiner Cc: Andrew Morton , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. 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 , Zi Yan , 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 , 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, stable@vger.kernel.org, Josef Bacik References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-10-6f74bec9a5bb@kernel.org> <5d431bf7-8813-4e2c-a40d-b45d4ff39a5b@kernel.org> Content-Language: en-US From: Mani Tofigh In-Reply-To: <5d431bf7-8813-4e2c-a40d-b45d4ff39a5b@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: DzBUE-I34SUdoYh-WFFnp9PYz5m0rbY5 X-Authority-Analysis: v=2.4 cv=Xt9vqlF9 c=1 sm=1 tr=0 ts=6ae0e793 cx=c_pps a=7E5Bxpl4vBhpaufnMqZlrw==:117 a=TdXXog4ttPu8yHJGq4T0ug==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=x7bEGLp0ZPQA:10 a=A0y_DWxS2BwA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=jHxIr1HyPKZ_Q5_91PL3:22 a=VwQbUJbxAAAA:8 a=pJWPUViXIfCbsMganCcA:9 a=QEXdDO2ut3YA:10 a=pJ04lnu7RYOZP9TFuWaZ:22 a=zY0JdQc1-4EAyPf5TuXT:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDI3MDA3MSBTYWx0ZWRfXx2ZpnP7DHh9w 2exT1+JDVzYv6Aye5EEgzztVsyOlDHTAZw09ajKphZCIgCVWbi9EyksLwK6ZSJ+rf04oFiSuOag Y6a+T7IBQMfL5aLfvtMNXhH2a1JavTNy+WhcUh32ZETTBLZZsTtR X-Proofpoint-GUID: DzBUE-I34SUdoYh-WFFnp9PYz5m0rbY5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDI3MDA3MSBTYWx0ZWRfXwKX2TrRNP5F6 0LDPH20wUSSWzhdCkEGFEb9wqkc/YVngvuPVnftB7USYvbcipqXoeolV9jBNaQk3YuP/EBPGMWG zBcY7GaWUUdKnbgrSw+tNAMGhUm7E68prffmaqLNHsRmFttsNbU8DLwV3PiY4MoAfOQvRrtrK4f 3JtDXtjDn2ddCa3l6CwgtD+YeE9RJSqJ1zHcSAj9egRu/0AiJ7aDUJPeBCCHU2Nn+2Gw3BzRYQu xjuzobVimvgJccCueABy4FuaI5AUqt8CiYov0vzG3xci9l+aEEBikEASnTH+gYT4PH18/m1ImE4 8NImZaVMna3MuI+pD8Wt0KD5SmSM2lG7F7lMkwwvUDChOjFzvNwaE7UCXluDtTGPx0tG5jkF1cM lMLbwL7MeADLTovJA3Zi5Sfqqeio01RHBF8vkb1ka14/WBetcIhwyYw0OufKJCjoa4VIVt6nwy+ umE/J0UchR85mdd37sg== X-Proofpoint-Virus-Version: vendor=nai engine=6900 definitions=11948 signatures=596817 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=10 malwarescore=0 adultscore=0 suspectscore=0 spamscore=0 priorityscore=1501 impostorscore=10 phishscore=0 clxscore=1015 lowpriorityscore=10 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610270071 On 10/27/26 11:15 AM, David Hildenbrand (Arm) wrote: > While I have your attention: This variant works, a different proposal used > > list_del_init_careful() > > instead. However, that is documented to require list_empty_careful(). > > Do you think it's worth looking into? > > > https://lore.kernel.org/all/20261026-thpsplit-careful-v1-1-d357d70fd6f4@columbia.edu/ In this case the careful variant is fine without list_empty_careful() since it writes ->prev first and then ->next with smp_store_release(), and __list_lru_add() only writes to the entry after it sees -> next == entry so it can't race with the ->prev write anymore. But your version also covers the PG_partially_mapped race your comment mentions, which mine doesn't, so it's the more complete fix anyway. Thanks, Mani