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b=ELqru6IaxAwNIZ8+Tc45OFVN6yyuai77lcJeNDhYMvPWKYrBGu4d41U3I/zY1ol0H WMPcex/20VhBcwadogTDxD8Bl3QS+LC7AjmMucLkiWPdGE3kO16JOiUnU+pdlkn8cM YRS4m0yD53aU2X4dmauwQ95vw053MS5vf45A2p+D/Zn1SvOowPTSpLD5g2AqdD1IgH vSS4uhrgAkqn/16fTmentlt99wBOnieuAnYB/j2JSWf5OqGRUMFhkZQnGBmtoZt9Oz 4IbrqQzXlEqy+LzN9+rMAKRZurNCv/9w2LG6XJbbyBGM4wejSOUMOr+NIGlK17YjOR 4S0Dur2/QI5dw== 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 6.6.y 1/3] mm/damon/core: skip applying scheme if region split for quota fails Date: Sun, 8 Nov 2026 12:25:25 -0800 Message-ID: <20261108202527.117086-1-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-Rspamd-Server: rspam06 X-Stat-Signature: 4ptxtjk5n5q94zd5f3bro4iiokphqjda 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: 81CB240005 X-Rspam-User: X-HE-Tag: 1794169535-515019 X-HE-Meta: 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 84S8BJqK luDnoa3ledYs3mlLqtF1lG1KkkDAHEqjXWCjx6e7GewHxMO5txn7Z3LEhHlVvDo+q98MB+kPen/3XWfxuvIMjbXZu6895BbVd3r0rmeT27J+KarkLI5jADhwb9H6ms+FoMuBzjr4410/BW+zKScUzHvK4YfjyZ0VrueSgJ2+PmBu6e7e6wuSVV16i6d+kn/qK8vOkmkfP53CyiJefTat3DJvEn3bo6NMm66MsLYXVAsha2MS7ia+VND4mbBGnXNTz5CrDRQn0gRQC8rmV9m3Q1OyLMMUO+NVo1eMCe2xoJUsxkFetqQXUC6baGi1WYga6lEUg 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 20:23:37 +0000 sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential > issue to consider: > - [Medium] mm/damon: false tried stats on split failure in > damos_apply_scheme() > -- > > commit 17459070b1916b2d77f607f0fb7f0f9158e6224f > 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 > damos_apply_scheme() if splitting a region to fit within the 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 b5b6d00d7a3b5..9d4a78deaa06a 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > [ ... ] > > > @@ -1004,7 +1004,8 @@ 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; > > [Severity: Medium] > Does jumping to update_stat here falsely inflate s->stat.nr_tried and > s->stat.sz_tried when damon_split_region_at() fails? > > At this point sz is the non-zero remaining quota size, and > damos_update_stat(s, sz, sz_applied) unconditionally increments > s->stat.nr_tried and adds sz to s->stat.sz_tried even though > damos_filter_out() and c->ops.apply_scheme() were skipped. Because > quota->charged_sz is not updated on split failure, every subsequent > matching region in the walk that exceeds the remaining quota and fails to > split will also add sz to s->stat.sz_tried again. Returning early here, as > damos_filter_out() does just below, would avoid counting skipped regions as > tried. Trivial user impact. The same behavior exists in the mainline. No blocker for this patch. > > -- > Sashiko AI review ยท https://sashiko.dev/#/patchset/20261108201456.116824-1-sj@kernel.org?part=1 > Thanks, SJ