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b=M1Kkziel5JT+mt+BbAP0GklAlCCvf0PmJm2wYMYvKor5d3e3BVSAsKzQj7eTVKB9D TuV5YrCgzN2oxKe7UOpyaZclF2ZmiNRz3JgxTEFBJd51t+vevyg76JCrUro8DmYwHK P7ZKUiZa3HR3wryTn6eXj/OdquHKSsq9fwsR6hIFAyPi9dSVxKCqe/KudwA263OnXh DDtkCnadu3k9E+xhy/uMD97nk5+MV9ZKjU9C/3zgkCjhhh0yqEezb8zTm0rx1d1J39 7Femx8GnfJ/yEYnI2i4fl2Jj3YecHz2wI8Kfjh6IWCHMP1bN2Dya3HezA2QbJAeoVM Qi8bMJWAo4PPQ== From: SeongJae Park To: Honggyu Kim Cc: SeongJae Park , damon@lists.linux.dev, Andrew Morton , linux-mm@kvack.org, kernel_team@skhynix.com, stable@vger.kernel.org Subject: Re: [PATCH v3 4/4] mm/damon: fix divide by zero in damon_get_intervals_score() Date: Tue, 1 Jul 2025 17:19:02 -0700 Message-Id: <20250702001902.937-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250702000205.1921-5-honggyu.kim@sk.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D8A5DA0002 X-Stat-Signature: 9a6w18kii8koacetpi79s796yw8zfxcx X-HE-Tag: 1751415546-922094 X-HE-Meta: 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 rdQokYuf xZZtf0O4CAAzdhJaQ7cbnJSta36DnCTf2v/l0CNOaoz9ssAw1yecb/ovL2FYY+dTRw2tmtnr6k5awzLPwybcyu7KGQ9Wq0lwU8PmP61t4XOwiQzCTjkH8guw08/FOlkTMaVaTqqII4RrZuxKcmmhxL9YpRiZCVXZzJQjPPOpeZ/iqxcYpljqF4rCt1x2al0SVHevSTIdhb1Ioh48fAzydwKkn48eGiM3oauiXFWjmjZA2uOGr137DNSaaaXCh2PbX8kC8JDgfF+WjlNweFJzHlJrcQt/4xfX4AiVxLL99CYwqjAxrbQvHL/wG7ZoZqUD2eZ4VkJ0KkHvP+fbzT1DNlSS7DQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello Honggyu, On Wed, 2 Jul 2025 09:02:04 +0900 Honggyu Kim wrote: > The current implementation allows having zero size regions with no > special reasons, but damon_get_intervals_score() gets crashed by divide > by zero when the region size is zero. > > [ 29.403950] Oops: divide error: 0000 [#1] SMP NOPTI > > This patch fixes the bug, but does not disallow zero size regions to > keep the backward compatibility since disallowing zero size regions > might be a breaking change for some users. > > In addition, the same crash can happen when intervals_goal.access_bp is > zero so this should be fixed in stable trees as well. Thank you for this fix! > > Fixes: f04b0fedbe71 ("mm/damon/core: implement intervals auto-tuning") > Signed-off-by: Honggyu Kim > Cc: stable@vger.kernel.org Reviewed-by: SeongJae Park Thanks, SJ [...]