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b=CoUmy2Rma6WejeMfLEwtc4PhzThuA/zydQvI9wcl51SkM0u4/qsFlzBi6r5FZ5qcF GyQky8AeSNCLeDlpesEmoTSgEF/rTZwuBEoFcsxCY5+eXfAn+5Zv4Q6w72Rk546ous +W0MEGCvVdNRtDDD9NP1LnrLwBUXQPQVBaLCpzju5656M/UH6DWk3HrflRhcarXBDE 0c+lZcqqqlj8LO53sZ05QK3+iuepD7BOrSqE+JXxHtpcIT3S2fg8XYSkgNfIBN3OTK Q0icmdizVUcH2b5VsCStw5c9X3K3ruM7+BBzybMF5OVBVdrr7Zu1QFXd6EcZNDUs6R sDI4F7m+YqZIA== From: SeongJae Park To: Junxi Qian Cc: SeongJae Park , akpm@linux-foundation.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/sysfs-schemes: fix use-after-free on memcg_path and goal path Date: Tue, 21 Apr 2026 16:47:30 -0700 Message-ID: <20260421234730.2917-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260421070632.161808-1-qjx1298677004@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 9E1E6A000B X-Rspamd-Server: rspam07 X-Stat-Signature: bw5d4ofkwk5p8tzwpzac9uiyhk87gsob X-Rspam-User: X-HE-Tag: 1776815262-800270 X-HE-Meta: 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 lCfXOAuv J0dsWmQwij3G01tcf51JAihY1iDXNWfMxQH36Y2Ecyxdeha5NGoSU7yNqAIvdHohNClV5hM2EFYoS70DJjwovzvoVLPKmNkIaFUakhK9W7uFp9DS+ncA7w5DKf1m3QO9LiFvoyHdpndcE8ZF2x/nq9/2wQ5KRg1KicLBuNpbr3z7WgXriPkKdnoRO5EUR44tQP/73sbgEx/BadxWHWdIYFYOKJhQ5Qq/AdqOx2vhMcABDfaNZpoNXqab2+eUyTFxtM8N93WfRSH5/NjZ02n6BCLCRwg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 21 Apr 2026 15:06:32 +0800 Junxi Qian wrote: > Hi SJ, > > Thanks for the suggestion. > > I checked the show/store race further and was able to reproduce the > memcg_path_show() side issue on a KASAN kernel. Thank you for sharing this, Jinxi! [...] > I will spend some time thinking about how to fix this properly. > > If someone more familiar with this code would like to work on the fix > directly, that would be greatly appreciated, as I am not very familiar > with this part of the code yet. I think you could protect the memcg_path and path load/store() parts with the damon_sysfs_lock, but using mutex_trylock() instead of mutex_lock(), as I suggested. If you prefer me to finish the remaining work, please feel free to let me know. If that's the case, I will work on the fix while adding Co-developed-by: and Signed-off-by: tags of you on the fix, if you don't mind. Thanks, SJ [...]