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b=mnrnE65YuUXx6wnZe89Pe8iU5GLqPwOxRUTc/lGakGTHrXAe056KH8+F0/0eC9+hd OuSgVk6eCFkMm1LUPnYjqoGChMnSnkildU6yWNvDyW7PFu/vSK+4HKx2pBaD+xUcgQ EUrgbXRoPKLRgDaLDX/I2kverlCh6icZ2CuahrzwSOCYjG6Fr8xic5NqUrOz3CbYGo txpfW1U/R+sbbMGNi+IY/AD5mar9Wm2MNK23PGQvJ93YrALvHjotp2RmWZB7jRkqts grePXrbvJB0zhp+wP3oMY34PmU3Vt8Gt+F8MNCh9RPK7K6VdCtDT6ODEEHEXjS6Rc8 szJr8/dx/SiNg== From: SeongJae Park To: Josh Law Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 3/3] mm/damon/sysfs: check contexts->nr in repeat_call_fn Date: Fri, 20 Mar 2026 17:54:19 -0700 Message-ID: <20260321005420.80596-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260320163559.178101-3-objecting@objecting.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: CEA73C0006 X-Stat-Signature: rxixqe8zjwd75x5noa86x3ygjq6m5ieq X-Rspam-User: X-HE-Tag: 1774054464-393765 X-HE-Meta: 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 dweBI1gY N9AoMxfqK4xOrGJ9JHztSaVDlk9NzqOU8U4RCx5udmLGZP0t0/baJPzy1HYqJMkJRSUIz49wJrSxAA78pD0z1VIvJ2oalC9F5HI4ho39myGWQZ/MXop/CVRlXWPE0hJf8E5d2S5bdqVT1gUB9J9jS5jSZCowEoquQaXeIs6pp3FsDQKptVdPtj1SuDL6e+MRr5AKQp5RFE/jwpka8xz0qQCzKhGBUySl+E5oV03KHAGelWyWZ7SH+437SB18BajDdElhZjUeJrUdxiJPqluzZFis+hyQJSU+P/8n4GfJmzivc+woFXmop3LlPDjPeEbPRYQfU3IwDH4qN4ALYrG0Z+8LkJXWHSiPp882pI8ax+aeMaix4vmp5KnCB9Y/dCT9kbOQVBIeg3M67Ogg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 20 Mar 2026 16:35:59 +0000 Josh Law wrote: > damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(), > damon_sysfs_upd_schemes_stats(), and > damon_sysfs_upd_schemes_effective_quotas() without checking > contexts->nr. If nr_contexts is set to 0 via sysfs while DAMON is > running, these functions dereference contexts_arr[0] and cause a NULL > pointer dereference. Add the missing check. > > Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work") > Cc: # 6.17.x > Signed-off-by: Josh Law > Reviewed-by: SeongJae Park > --- >From the next time, please add patch changelog here. [...] Sashiko also added comments [1] that are very same as those for the previous version of this patch. I replied [2] to those on the thread. In short, nice findings but orthogonal to this patch, and I will work on those separately. [1] https://sashiko.dev/#/patchset/20260320163559.178101-3-objecting@objecting.org [2] https://lore.kernel.org/20260320020630.962-1-sj@kernel.org Thanks, SJ [...]