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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-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: d1yd9qgxt94yqf4q87dn8ie4zxfpaeo9 X-Rspamd-Server: rspam01 X-Rspam-User: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 93D321C0004 X-HE-Tag: 1794171708-725208 X-HE-Meta: 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 q37OOaPM ckg28jidSRSzqm7b2QEjOkMTW3Cr1uA9JOSYeFX+/MNjn67rvi2KmlkywpUsJj+UsUMbFMc6Nn2j8kKXtkz8LPPgcJM8cp5Op/31BQBYbAnjT/YlM2Vsx2H3PDvuE4EK0z361I7AsrvbokxFSkvs3TfatphYOkKemzKQOg+gRHdDJasOJ8cUNgStA8PoDW/QCIF6p5G3BiCl01npLkxaRn4aGg8hVfBg4lql1lpY+eKZ56/i5VbBT91088cpIHDpnV14zEx8+99+KEHH9u1Vct/ULAYO3fek0xHtFa0bLIlcYQJbtx6GokS9Le0ol9iNShJ8P Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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