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=1794088833; b=CuZT49IL1+kHXHcQBmmY7WriDwgt+4Drrty2gRa8/3U4GPFP2QxjdpVIdF4uF2Xf16t3 aa/v0drJ3DkXR+zI8CcOSS+6v9MuENNBIcCSjoaflihAMfvTkrp1WqGxH0y0hwvx633Q0 KUzv8FqEM2RuOuCMrnHa9U+rILeObYXWtClnr311nz9xQAJbpHpqj0WQ4ZYXHFtfokHHh qnPoxDpfzz6E3WyxdWCwPuBoINnIPLrPYfpVT+t8+nv161gAeLf0nel/8a0KTIlIiNeJH MUtHwXDqHTAlub3iUJpy91SCJSmLRDyfaCQWrcyqxsKvTwviAiDBHOsqOULhBXl9+Hg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794088833; 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=YJGz7I7p/AgQ7qim32bWeDztlYgVQCLK2LaoTD7wEVw=; b=2qwghOZToQAw+c8RV9J3CHl59X8vY8PWrmnLa49i1VdJ4c2ik7hzc5IHNQXNkIMeG7Vi /TzArExnECkpZjMI/Ln2vBelOfbmObhdCS9TSMGHoSk0UYFJqgvSuT4M54Gv3ZnjE7c+4 pycFRBNXiz061a7bx4kIcHgK6qLN9EUX2XISL0OyKta5m56N4jnS3nA3XzR+lmnP6Twg0 NikCwpBE1VIuasqBKCnmdCdJZs2cPP4y34pRtBdwePrDna+T83fjV1Ct8Vs0cOYAagOUx 8axL9vlH0gbpQ+bxP0LALSEIzbygHs9kKbf19DnYfOKip+hhRL0/UsvqO5UI95BvnwQ== 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=oui3YcWg; 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 16A7A606A339 for ; Sat, 7 Nov 2026 22:00:33 +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=oui3YcWg Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD8911F008A5; Sat, 7 Nov 2026 22:00:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794088832; bh=YJGz7I7p/AgQ7qim32bWeDztlYgVQCLK2LaoTD7wEVw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oui3YcWgTyHT/b1HeHr7nKHqzAN+cTjrI839oHsP4imLid3duglI+zzqrfXWPG1g4 nT9CGhvde8GTdv2lnnU/2PJmbieoexL9pbaytkgUX8BESUuWZLdYCAUhWSAwP0pTOD hZQ6IZq1+hlqoj4ptMAMAigbhhA+G8qtkV/qc9K2mI8tRgsRH3N9d+gsQLdNg2jNJL T5PFMZzZQ8KOLtc7U6p+0B3gPsYSSdGbypAl/KGVya8JcktErSwVIa13ijS5AvxQaE B6aAydbkVFh1dzgvahkPN8uMogbkVwiH1JI+D7S9g7k9EMggjHvIEV+XI5DD8XMA+R yhqOFmzIzg/1w== 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: [RFC PATCH 6.12.y 1/5] mm/damon/core: skip applying scheme if region split for quota fails Date: Sat, 7 Nov 2026 14:00:24 -0800 Message-ID: <20261107220026.304899-1-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 Sat, 07 Nov 2026 21:52:35 +0000 sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential > issue to consider: > - [Low] mm/damon/core: inaccurate tried stats on split failure in > damos_apply_scheme() > -- > > commit fe019f891ca813eff979dfc83e95ba297bc45135 > Author: SJ Park > > mm/damon/core: skip applying scheme if region split for quota fails > > This commit changes damon_split_region_at() to return an error code on > allocation failure and skips applying the DAMOS scheme in > damos_apply_scheme() when splitting a region to fit the remaining size > 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 81d44e41de210..6ef77741b783b 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > [ ... ] > > > @@ -1470,7 +1470,8 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, > > 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; > > } > > if (damos_filter_out(c, t, r, s)) > > return; > > [Severity: Low] > Should this return instead of jumping to update_stat when > damon_split_region_at() fails? > > At this point sz holds the non-zero aligned remaining quota, and > update_stat calls damos_update_stat(s, sz, sz_applied), which increments > s->stat.nr_tried and adds sz to s->stat.sz_tried even though scheme > application and filter evaluation were skipped. Because quota->charged_sz > is not updated on this error path, persistent allocation failures across > subsequent regions larger than the remaining quota will repeatedly add the > remaining quota sz to s->stat.sz_tried and increment s->stat.nr_tried. No blocker. The user impact is minor and constrained. Also same issue exists in the mainline. If we want to fix this, we should work on the mainline first. > > -- > Sashiko AI review ยท https://sashiko.dev/#/patchset/20261107214525.304638-1-sj@kernel.org?part=1 > Thanks, SJ