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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-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: x46iw5abns1h5mbgzfuwebyyi88kgrxj 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: C9F9280005 X-HE-Tag: 1794088833-137794 X-HE-Meta: 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 73k967Af F7pRDWlCC2s8n5px03G1zKxtgQJMv5feNBalJ6Ddz2073pG52mItMvXSLsQhggwloUhImSxH2BCY8OZS1yoRI+9MHjZa/zBh4Vritr6bYLW+YZAD7oBdzDrcpu1hXaysXYovF/3fsn3hExB9zDKOhx3H7lDyjBvzlU9sqCZKVmxeeEKkBPgh98PLRzlUnXnRhWMn9slQXyVbnQJzym4jYcLMXRKBsijHWHqVQ3s4RYinCjkAJVcyPG+ULoN4B0DLspf9Fu6Zq/N2DIpjn373OBCWuu/IKgG4wkeaC/DqzI0W+oveGJlhrg7MKG4pdS6DbBhhr 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 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