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b=nTm0b95qgrff+QxYQfesDPwKrrL3LF3vu3i5qbdg3GgNN5ixfYjsTPZ7bC+Uu9Jjl ex84bPnshtoXqo/05QEzk42b9UCM4g+JX6C3lvBV1AeIwG8B7pflym4wCUF0DOBQkc j8LcG+sklUYJ6v3qnwIkZWJM6VYZ051BddzuzKjGVQPWbf+RmQS/zvJcMttMeJyHVo psdeX80RhJcBO7i93RIsZAG1OfAeE4C2uiPMSRs6iyt4XixqiNVzE4ZTUFOlt863xp FEStjzTBRyEl8oeYSr47E8VOFH1XRqNypGOrJQt7SOTwS5i24EP2mknqueMLxLPnCu q/v/ycrABYj2A== From: SJ Park To: SJ Park Cc: stable@vger.kernel.org, Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH] mm/damon/core: handle region split failure in apply_min_nr_regions() Date: Fri, 17 Jul 2026 18:16:34 -0700 Message-ID: <20260718011634.94132-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260718010312.90397-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CF12F180005 X-Stat-Signature: jcphe37b7hsgb8xjxgztxy9xr9zbkqxt X-HE-Tag: 1784337402-349759 X-HE-Meta: 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 5zvjrEc/ GOa4WFk+PlucDqhkAGUpLmZxJmtB7WxFiwPhNZo5Ru2WpeKFqi1Yo7gY4Ax++4Ouv0jDKfJIsMDkO+mpksEkff2d+jhG0CoveakECc9N7ppkKqlwlpMHTViq7IhE1xg+ODyeERuP5lQMRHaTp5dxYH89CiVAnD7uWPw67swhK6XSHeolvyp193391Baar+4er3r5GTE+ajf1wBSoeiQtvYVqSl73/k6hSAlwVu+YD6dCcNNHJ007+ZAYJzqOS9OX+SIZeEpNnNPGd18ZTX1uQCJmS0w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 17 Jul 2026 18:03:12 -0700 SJ Park wrote: > On Fri, 17 Jul 2026 17:43:00 -0700 SJ Park wrote: > > > damon_apply_min_nr_regions() repeatedly split each region until its size > > becomes small enough to meet the user-defined low limit of the number of > > regions. The loop assumes the split operation (damon_split_region_at()) > > will always succeed and create the new region. But the operation could > > silently fail for memory allocation failures, for example. If such > > failure happens and the region was the last region, the linked > > list-based next region fetching returns invalid pointer. As a result, > > invalid memory dereference and corruption could happen. Fix by breaking > > the loop in the corner case. > > Sashiko found no blocker for this series. Sashiko sent findings to damon@ > mailing list [1], and I replied to all the comments. Please read those for > details. My intention was to add this reply to other mail[1] but I only mistakenly replied here. This is true, though. Sashiko found no issue in this patch. But that means nothing since this is an RFC. I will repost this patch after dropping the RFC and rebasing to latest mm-new, tomorrow. [1] https://lore.kernel.org/20260718011322.94001-1-sj@kernel.org > > [1] https://lore.kernel.org/damon/ Thanks, SJ [...]