From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2F7F51E5B64; Sun, 12 Jul 2026 17:23:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783877020; cv=none; b=mGjSaagsIj5MwDor+bBJNQKUP5xhTgqvCrZMqNlojNybL8sPdKQ8JxNUM++8ZXS2Hd58xqGTupcU5lcaUkyztPUkwmBEuWNLFRVwZrw7CW4rU700QCRZNaDH14dButS9zZzA+eKegSpjksOOdlV++74FAhakP7Jdbt6ZZa0EmpE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783877020; c=relaxed/simple; bh=2bvgYPt+GqQeBP3pjiVPuadeJRieLBCmg5szj7F0/Yo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u5Gz5OEcPEloFxFKTmnWaiOVfRHCWP1kq+W4B2HifzwDlipmqCCxCzlu2zbILuKsRCFysY6WF9A8Lf/5DonlOiQyLkNufFykNGvpD5PBZAZZ8Az8ZYUGmIkE6wIFj2KTrSlCgEt7gcYUwFR9g5v/Mb7uJ3HS9xoeNh2FzX3sPYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VJKVgeN3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VJKVgeN3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A08B51F000E9; Sun, 12 Jul 2026 17:23:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783877018; bh=erlvsdImMPOzbt0J1t9Lju9UV9yCJY2fVSin6DJP3CM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VJKVgeN3+Qn9GQFaBZQs61WHX/XKRIQzg+VY+N85N3T4lXGBLDHUw6/kFxaqHeTDt hSjbJ90rPOVOp/1M/6hIflDQN76PPxSyWqZO26rX6kvVtXrkviX6esW3Ecq/mKDDLn cak6LKA9nGH4Tv0CmidCuQGTFUSRm9puODoduSJpRCxbrrX+RTjitGDi/WMLLSd1hZ cGY0KNWr9a1qrorOJixlRykl4c5vVDjPs/yRFLYC8j0M6Nh1eh9HfMllpE2+979jlM zfRtDJ7ZASjMRh/bLGJyhfboi66TXhAI8LRbPq7B0TJIJ7V6uU+4wbZKE57By28zEr 22ICvS1YigYNw== From: SJ Park To: SJ Park Cc: Andrew Morton , stable@vger.kernel.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/core: skip aging from repeated aggressive merging Date: Sun, 12 Jul 2026 10:23:34 -0700 Message-ID: <20260712172335.92448-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260712165432.87609-1-sj@kernel.org> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sun, 12 Jul 2026 09:54:30 -0700 SJ Park wrote: > The number of DAMON regions could temporarily exceed the user-defined > maximum number of regions limit for corner cases. For example, users > could lower the limit via runtime parameters update. For such a case, > kdamond_merge_regions() repeats merging regions in the case doubling the > merge threshold. The repeated merge operation could update the age of > regions multiple times. This corrupts the monitoring results. Fix the > issue by asking the merge operation to skip aging for the corner case. > > The user impact is degradation of the monitoring quality. The impact > should be mild, since the degradation is only temporal, and it is not > common to happen in realistic setups. Sashiko found no blocker for this patch. Sashiko sent findings to damon@ mailing list [1], and I replied. Please read those for details. [1] https://lore.kernel.org/damon/ Thanks, SJ [...]