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b=d6MT47PK/nb0gL3PL+V22I42qqTQfK18II2EorZdzWHtojpJVZNlWtmQ+37mUkYjh Y0yWccuPEEhF5tSrmPvN/LCf4LMchXvSIDvncOT18JQdVtT7fnb4xb8K1xVxyuNIQx z7jkjqA/+P5njS7ATivkITJ2zPU4ghBT+ch/3cCLYZNgJhxUHha8Vno0np65eZ4KmO Whyeu7/lP57xuQVshQ/QgbJoqL5glCaG8C3y2Q8l9DAAZESglJk+cWlWNYXq62UswQ DBvq2G/j7qkKWaFaKr8uP8K/6YtGEpQhbdCAROj4NQYfqj9nxs5+AluGU43PpaUZGZ i/37VzwSYk6BA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 6.12.y v2] mm/damon/core: handle uninitialized damos_quota_goal->last_psi_total Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: "Andrew Morton" , "Brendan Higgins" , "David Gow" , "Quanmin Yan" , damon@lists.linux.dev, linux-mm@kvack.org, "Lian Wang" , "Kunwu Chan" In-Reply-To: <20261109011347.92467-1-sj@kernel.org> References: <20261109011347.92467-1-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 09 Nov 2026 01:28:24 +0000 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7201840008 X-Stat-Signature: c15gfcm4to461ttr7m7w5dpmf4ujizge X-Rspam-User: X-Spam-Status: No, score=-10.8 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 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794187706-835613 X-HE-Meta: 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 5r5AjVxT 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 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 X-Archived-By: Thank you for your contribution! Sashiko AI review found 1 potential issue to consider: - [Medium] mm/damon: integer overflow in damos_quota_score() on first PSI round -- commit 5e9b1f636c184ecf41e05d717ad5e0116b0fca20 Author: SJ Park mm/damon/core: handle uninitialized damos_quota_goal->last_psi_total This commit initializes damos_quota_goal->last_psi_total to U64_MAX when creating or committing a DAMOS_QUOTA_SOME_MEM_PSI_US goal, and sets goal->current_value to goal->target_value on the first tuning round so the effective quota remains unchanged until a baseline PSI reading is recorded. Link: https://lore.kernel.org/20260902002725.108635-3-sj@kernel.org Link: https://lore.kernel.org/20260718005316.89585-1-sj@kernel.org [1] > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 3142776e2e0ee..420ef0adaa7e3 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c [ ... ] > @@ -1616,7 +1619,12 @@ static void damos_set_quota_goal_current_value(str= uct damos_quota_goal *goal) > break; > case DAMOS_QUOTA_SOME_MEM_PSI_US: > now_psi_total =3D damos_get_some_mem_psi_total(); > - goal->current_value =3D now_psi_total - goal->last_psi_total; > + /* uninitialized last_psi_total; make no effect this round */ > + if (goal->last_psi_total =3D=3D U64_MAX) > + goal->current_value =3D goal->target_value; > + else > + goal->current_value =3D now_psi_total - > + goal->last_psi_total; > goal->last_psi_total =3D now_psi_total; > break; > default: [Severity: Medium] Can setting goal->current_value =3D goal->target_value here overflow in damos_quota_score() when goal->target_value exceeds ULONG_MAX / 10000? Unlike mainline where damos_quota_score() uses mult_frac(), this branch computes the score with direct unsigned long multiplication: mm/damon/core.c:damos_quota_score() { damos_for_each_quota_goal(goal, quota) { damos_set_quota_goal_current_value(goal); highest_score =3D max(highest_score, goal->current_value * 10000 / goal->target_value); } } When goal->target_value > ULONG_MAX / 10000 (for example, above 429,496 us on 32-bit architectures), goal->current_value * 10000 wraps around and produces a score below 10000, causing damon_feed_loop_next_input() to increase quota->esz_bp on the first round instead of keeping the current quota unchanged. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261109011347.9246= 7-1-sj@kernel.org?part=3D1