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 7CCDD242D97 for ; Tue, 23 Jun 2026 00:23:22 +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=1782174207; cv=none; b=HDDrlI977peXd8NNb+MVurE3fE6WmOwqPArI6y/EvlF094ZOEMkX6OiOdrqLh59oqcdrF17jenvW1xeuDLCwk4ITbOhxMeSFRxyWhXomTzsh1FKcokcTAZNvsnBnvD2OX/K/oPfaeMOZeMWU7IO3O2u94+aZiKpo5onuYwwQLe4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782174207; c=relaxed/simple; bh=+7RUoZfgemk3EBcm1NS6Peh9pAOsCTQAi07EzGTGxww=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EztIXwaGIl0rAiaxS64Jm/oz89bLko/75xw9mtHjb0NZ3JWMioQJhDiagUvj9+rSIOU2N9bh9F05APl9sdKCSCasA7dFwrbesi+5lIYJ8ff9CkPDVYw4urGIcXJwvtTS3EGqqbw7jdkSl3sPyo0eHlRiwreHJBE7s6DQC5vKsgM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ydg9Oc4A; 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="Ydg9Oc4A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CB141F000E9; Tue, 23 Jun 2026 00:23:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782174201; bh=EcYUI71nDFOJP6eTeRXLhyFfnaZafEFTLQruZThxr7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Ydg9Oc4A9lZuSiESDcAT7xb4JlS0N070ZQnIXWbxf8KWDs3FBPlqcY9r6kOuvvkCr Hiam3TvKNZv+ERF/nTkxpY6wSqEST7e/fwGAUmzBFO8qhzmcR8uzHglhj/KAJxFK0Y IcJ+A02E8540PE1l1rvYJnFqEJe4i+W0EuXLHBz9PR2zIh/c3rudeN22aH24C6UBt4 ceq+9sPKp/CBHtWeOTx87QtF+Em2tgi9V4iEEdsJYaCjwN4jzPMQa8wq9lEns0xKSv JSuCEgNTWwE7m9dtX6OGojwr5IoBZgv3I0Npm8pO6FK5nsNl2ccBGXdz6WzT1OvRn4 WoIpP5dqaQFug== From: SeongJae Park To: sashiko-bot@kernel.org Cc: SeongJae Park , damon@lists.linux.dev Subject: Re: [RFC PATCH v1.3 04/18] mm/damon/core: handle unreset nr_accesses in damon_nr_accesses_mvsum() Date: Mon, 22 Jun 2026 17:23:12 -0700 Message-ID: <20260623002313.35582-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260622144211.CE27A1F000E9@smtp.kernel.org> 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, 22 Jun 2026 14:42:11 +0000 sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] damon_nr_accesses_mvsum() incorrectly returns stale access data from two aggregation intervals ago during the aggregation reset gap. > -- > > commit 079525184ff6b3e5e3e7c3387647af444428cb84 > Author: SeongJae Park > > mm/damon/core: handle unreset nr_accesses in damon_nr_accesses_mvsum() > > This commit addresses an issue in damon_nr_accesses_mvsum() where unreset > nr_accesses can unnecessarily inflate the pseudo moving sum. It adds a check > to return last_nr_accesses directly if the remaining window is full. > > > diff --git a/mm/damon/core.c b/mm/damon/core.c > > index bc40a6d10f277..8a7351b4a27c2 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > @@ -268,6 +268,9 @@ unsigned int damon_nr_accesses_mvsum(struct damon_region *r, > > ctx->passed_sample_intervals; > > left_window_bp = mult_frac(left_window, 10000, window_len); > > > > + if (left_window_bp = 10000) > > + return r->last_nr_accesses; > > + > > [Severity: Medium] > Will this regression return stale access data from two aggregation intervals > ago? > > If damon_set_attrs() is executed at the end of an aggregation window, it > advances ctx->next_aggregation_sis but intentionally does not reset > r->nr_accesses. > > During this unreset gap, r->nr_accesses correctly retains the fully-aggregated > data of the just-finished window, while r->last_nr_accesses holds the value > from two windows ago. > > Because next_aggregation_sis was advanced, left_window_bp evaluates to 10000 > in damon_nr_accesses_mvsum(). Does the new check fall back to the > stale last_nr_accesses, skipping the most recent interval's data? Too minor issue. I will keep this as is, and work on further improvement as I also mentioned on the commit message. No blocker for this patch. Thanks, SJ [...]