From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794171707; b=Tp2bxrHnvVVnmtlZ4rb9eipvDAsG5GeDbrlUbrHlqAmx60n6uSogR0oiX8/KXnEXxNk3 KrudzHgMPqyEpQsr0NQC9h5SUJ5o4uzCFvc5lDZInkd177dvtYRVzuJc6n71d+938rZsW CxsMitpiF0zezd+vDLKlTktxEV1sQwQQ9WNP0VUaOWA2lhgvF+3SGyskgD4sUV8vIBXO6 U/zQu6KC7+sxU1/JISzw7ZgYOOi8IK9q2gy0aqYS+2TZmsC59XdxYIWrkM6hXg6mTZiwc VGbK4NCuGAA7MNT0Rhlpkfui7ed+0Z/2jvZD3TjnkzvEFtEecx3xFBdLVQZUr8JclrA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794171707; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=LlRw1T3EhDLk7qpw1Iv3e7L77NPv6Myz+uuZpVhsszI=; b=ZTfFz3sAnzueZ4iZx1YaBG4vf8obvkab8TOpJftkfeYV54E6jmtTVNSi9EMKnNsInRlS z8ttOoL3XmMv6OGPHTyWGECPrU1SQs4cbTXgUEnCNPKRj/vEkPKR6cmFZkfAEW/1kFdpm 4fWrNXM3tvLVxV0gBua59/04sCXRYlvlrqSuLLWP/9LYrQJiD9USN+ACDDzly/HMLLJ0o LDJ3WKPOhlzMiITeKc1hSTi0P+6J4vnpnR3rUschZIxo9L1FciEr16H9kgMi1gZs0e2hg ATMJSKSzI4xzVG6xyfwtzfXmDCQ5KY9ul10whSRDXD8lhhNbpwlYx2/eMrLTv1wnxRg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=BHvQJEZm; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6864D606A321 for ; Sun, 8 Nov 2026 21:01:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=BHvQJEZm Received: by smtp.kernel.org (Postfix) with ESMTPSA id C728D1F008A1; Sun, 8 Nov 2026 21:01:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794171707; bh=LlRw1T3EhDLk7qpw1Iv3e7L77NPv6Myz+uuZpVhsszI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BHvQJEZm1OHVlrkHXPv0o9B3+mNxp6d8OeOu8Ms2swuGncA3vCencR/PNNlMeLHbS FTqXLaA31Q+LSWY0NZq6/xtPOa/7Y9LzeGnonavPI94pD7bAMm9Z2CjarWPQjLLE8t 9c7jmyaWMvXYzsUqhwywIGmOTG+QDHV/QvovtcbNLnCGpYiUNNa+L7XGjaIWOhadFV YHo91DIFEGM8C/7m0NiLxQNJewxOmKBmcMBXgWOGWt72q23QgognUsvRTJYofz+Qwt 8j6u5mVmzv/T2t/ya717XIuGYvd2AnyefCvwyhB52UxoIyi3nu+mAF2b9C8cHgzNrb 3pcHTOnAozH1g== From: SJ Park To: sashiko-bot@kernel.org Cc: SJ Park , "Andrew Morton" , "Usama Arif" , damon@lists.linux.dev, linux-mm@kvack.org Subject: Re: [PATCH 6.1.y 1/2] mm/damon/core: skip applying scheme if region split for quota fails Date: Sun, 8 Nov 2026 13:01:38 -0800 Message-ID: <20261108210140.908-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: X-Mailing-List: damon@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Sun, 08 Nov 2026 20:36:18 +0000 sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential > issue to consider: > - [Low] mm/damon: inflated tried stats in damon_do_apply_schemes() on > split failure > -- > > commit 3b087258b4341cba87012b7cb96ed676fd164c12 > Author: SJ Park > > mm/damon/core: skip applying scheme if region split for quota fails > > This commit updates damon_split_region_at() to return an error code on > allocation failure and skips applying the DAMOS scheme in > damon_do_apply_schemes() when splitting a region to fit the quota fails. > > Link: https://lore.kernel.org/20260901131850.98037-1-sj@kernel.org > Link: https://lore.kernel.org/20260901131850.98037-2-sj@kernel.org > Link: https://lore.kernel.org/20260718171523.87547-1-sj@kernel.org [1] > > > diff --git a/mm/damon/core.c b/mm/damon/core.c > > index f0da5cb2b88a0..9206737d05ae7 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > [ ... ] > > > @@ -810,7 +810,8 @@ static void damon_do_apply_schemes(struct damon_ctx *c, > > DAMON_MIN_REGION); > > if (!sz) > > goto update_stat; > > - damon_split_region_at(t, r, sz); > > + if (damon_split_region_at(t, r, sz)) > > + goto update_stat; > > } > > ktime_get_coarse_ts64(&begin); > > sz_applied = c->ops.apply_scheme(c, t, r, s); > > [Severity: Low] > Does jumping to update_stat on damon_split_region_at() failure inflate > s->stat.nr_tried and s->stat.sz_tried? > > When damon_split_region_at() fails, sz is the non-zero remaining quota > size, c->ops.apply_scheme() is skipped, and quota->charged_sz is not > advanced: > > mm/damon/core.c:damon_do_apply_schemes() { > ... > update_stat: > s->stat.nr_tried++; > s->stat.sz_tried += sz; > ... > } > > Because quota->charged_sz remains unchanged, subsequent matching regions > can repeatedly add sz to s->stat.sz_tried if allocation continues to fail. Trivial user impact issue. The same behavior exists in the mainline. No blocker for this patch. > > -- > Sashiko AI review ยท https://sashiko.dev/#/patchset/20261108202759.117377-1-sj@kernel.org?part=1 > Thanks, SJ