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b=CJBaMjfodQ2EPymXCu+99Y9+PfziY+f4YLesTvmbV6Guo3XSepQ61uSoyXce528aU aJ0/Nhj9oJJBzdOeCIE2CET/bCGPSO43qdw0eiYNz9YRxVMg0WTYFKZWqQOaaVL3kp TorbCtfAKwTUzdZ97w9yWKumN0uS/MQU2B/YDAR4cXjQaiFBWN3H0nE0k0XtVFIJ6x oWx31gPtoK/Jny6zsSdRTHYUnpzbBIhk9oNiFoblLsb2ruId5aK8BdxpNG66sJi3sd /uYldeun5FU5DVwpAGHFqA+k6H5HZFZ0IWjk1r5TF1ZrhL0U/GPdm1Xv+EquTz6rSh xrlk9L7+QQv5Q== From: SeongJae Park To: Liew Rui Yan Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org Subject: Re: [PATCH v3 1/2] mm/damon/lru_sort: validate min_region_size to be power of 2 Date: Mon, 6 Apr 2026 08:50:50 -0700 Message-ID: <20260406155050.47762-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260406094116.13164-1-aethernet65535@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 6D3308000D X-Stat-Signature: p8zcyde4u7um3py767d9hdu8gconma5n X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1775490653-862022 X-HE-Meta: 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 wy2ym4iL xPkLMqISEzBZOviSBcN9aVu0Je1Nlb0vJ3lIRCyW6bbONg2IZMGljfTIH25q6kRwArcQ0keHa/KjZcE0GSh8Vhb1D+6yqyuXBXTghD51FFGK4KQpemE9g/3QyS3NpRdqb2uGsEt5sm1O5O7pHvo+eNaElVmWilGdd7ew7tH4Ei9x5aM+e0y0TXqdiuMix9CzG68Hgy/5WQZToNsXEbddQZGavg7daaZiekNrCr1tVVYgzgJ5WjvUKFy2GotDGpmsgRNzn4TNZxqwXUerBQOJWkT5HkFUfTLJRrpyHEjV8hUpjxYk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 6 Apr 2026 17:41:16 +0800 Liew Rui Yan wrote: > On Sat, 4 Apr 2026 13:30:43 -0700 SeongJae Park wrote: > > > On Sat, 4 Apr 2026 17:11:22 +0800 Liew Rui Yan wrote: > > > > > [...] > > > I think this deserves Cc stable@ because: > > > - The issue can be triggered by accidental user misconfiguration > > > - It causes kdamond termination and hard to recover/restart. Once > > > triggered, kdamond remains in an unusable state, and I have not found > > > a way to recover/restart it through the sysfs interface without a > > > system reboot. > > > - The fix is small and low-risk > > > - It improves user experience on stable kernels > > > > Thank you for elaborating this. I now think this deserves Cc-ing stable@. > > Thank you for agreeing to Cc stable@. > > > Let's make sure the user impact is clearly documented on the commit message. > > Also, the code change itself and the current commit message is not clearly > > explaining how the real problem (DAMON cannot be restarted) can happen. Please > > add the description in the next revision. > > I will add an explanation of why DAMON cannot be restarted in the next > revision. > > > [...] > > > > > > > > > For stable@ Cc-ing patches, more clearly describing the user impact would be > > > > nice, and helpful for judging if it deserves that. Could you please elaborate? > > > > > > I will add a "User Impact" section in v4's commit message: > > > > Yes, please add this kind of message that make clear what is the user impact. > > > > > > > > User Impact > > > =========== > > > Currently, if a user commit an invalid 'addr_unit', kdamond may > > > terminate abruptly. Once terminated, it cannot be easily restarted > > > via sysfs, pontentially requiring a system reboot to restore DAMON > > > functionality. This patch prevent such termination by validating > > > parameters (addr_unit and min_region_sz) early. > > > > You mentioned it cannot be restarted above. The above message sounds like > > there is a way to restart it via sysfs, though it is not easy. Please make it > > clear and consistent. As I also requested above, please add the internal > > mechanism of how that makes restart unable. This itself doesn't explain it. > > Thank you for your correction. I will make the description clear and > consistent, and also explain the internal mechanism > (the 'maybe_corrupted' flag and why writing to 'enabled' cannot recover > it). Sounds all good :) > > Note: > Please excuse my slower responses in the coming weeks, as I have > upcoming exams. I will be most active and able to follow up during > weekend (Friday/Saturday). No worries, take your time :) Thanks, SJ [...]