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Tue, 21 Apr 2026 21:31:53 -0700 (PDT) MIME-Version: 1.0 References: <20260421070632.161808-1-qjx1298677004@gmail.com> <20260421234730.2917-1-sj@kernel.org> In-Reply-To: <20260421234730.2917-1-sj@kernel.org> From: junxi qian Date: Wed, 22 Apr 2026 12:31:43 +0800 X-Gm-Features: AQROBzAIFaiXid7kxspoe9kHcMj4Dl65yuqKyQFsVGoaGj2cu0HUaj3kNW0odis Message-ID: Subject: Re: [PATCH] mm/damon/sysfs-schemes: fix use-after-free on memcg_path and goal path To: SeongJae Park Cc: akpm@linux-foundation.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 34EA7180004 X-Rspamd-Server: rspam07 X-Stat-Signature: fi8fhyghcg68h7phrg7hri7dbfrnkr9s X-Rspam-User: X-HE-Tag: 1776832314-437159 X-HE-Meta: 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 VWkQWHR9 27kRYpoDEYKHtBQ+Sc5+gAWxRPbIAvOBcfmiEKjA6Zs2wd8Q80W2G63HgXSJbU/NiSS3uCIBCMnV+TX+EhNWMAqCs5ZHqLfX0VSxRPs+/1LwGKRkaYvMngwyRHr0wlS75OAfb2aW4KtULJcffPSnUi7CtqXHPOHs5XhFOY9PmtyS7HwGJsUBpg1Txp2vEopJuHc4f6q2WNURrVQ4jSebQZO0191i41FMbBEOz3BUvaMKLqS7DWQoxmtehXrjq8AjcfkRAQ3uYS0QRj5J2xrlZ0aH4Kq+U0PoFAjV+gsO70FT2y+zKFRt43dnJm43K0NN+4R198A4YnQbG6aTnVQvHjsk7wwr+RZy1fevm5tK6uJN8hdDCqOhEh13ZSA26nZELZ74ABG57FSA0uvyq8SjQ9ziIbSe+x4dRoFfn66295RObBSW0GuGUcQnGNpVgEjKqp6jlFzVZAdx3o3UiMPFIb7xm3dDVSlLIwViLkr8i71WhCMMPe2EsLTEt6g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi SJ, Thank you for the suggestion and for offering to help. It would be great if you could finish the remaining work. Please feel free to add my Co-developed-by: and Signed-off-by: tags. Thanks, Junxi On Wed, Apr 22, 2026 at 7:47=E2=80=AFAM SeongJae Park wrote= : > > On Tue, 21 Apr 2026 15:06:32 +0800 Junxi Qian w= rote: > > > 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 fr= ee 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 > > [...]