From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE62C18B0A for ; Mon, 6 Apr 2026 15:50:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775490652; cv=none; b=TeVg9qy5ha23ArkRzQI//YqicfGLHoY+mQuoFJF2f3OlBZcCGbpo259/CZ2qlGakroElgKHwp7jxkmsVy9dGWxLN6lrHOsG73KN/Uf7ML8sqKGTQvfoecqJpP+Cnjqv06q1WzMNlJAqTz29lVLtIektpJJ6B6TNRn+Uvbc9YAls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775490652; c=relaxed/simple; bh=tjMRSF1p4+VSnXJtffjcLVXFwq9VwyFQ1AbNrZCxpj0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FXxA1CpUrDzpNqIQkjXu12MBedcd7XqYv0/cq0Z4iboIiVD0h+ztAvHHWlAF1sWDyMkuh1kdVe+XOpGPas0uawVDxQgqnI9q4RDikNWUZQg1SfCrT/xeCrkH8bx7c9JUkbcDKsdS7dtqXVq+jnOA3YY88DbkFHay4UOuICH3Wog= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CJBaMjfo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CJBaMjfo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38976C4CEF7; Mon, 6 Apr 2026 15:50:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775490652; bh=tjMRSF1p4+VSnXJtffjcLVXFwq9VwyFQ1AbNrZCxpj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; 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: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 [...]