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b=UGNL6kXoOYwOpibJRxflDNDon+6aCUMlKuw6KGRZ7VHYzBolgaq9QxuQ/bNnbq0dQ /E/B8tzEMLtRj7NHuubbsnxi0UUrtuJAeFR8KIexOyCNAgkq9c4FvXhMbzF5qD0yvL u+tj1PyaXx0LjslbANxnJa51SMbUwqWdGTaML4QO5gVoVHG5FwOAPW2GMZalSUoMn8 bMyhqq6+LoqxDSPNPBNdDlLR1T642dLY5efynodVIfD9oearsBEoGOdsIEE3XhAxWG cOo/dJjpFV3yiAzlQAoTAiny58zIWqvHcclSxaf1zMApW7vvCHQ6bVH2AZdRfnlBA6 CmZZ5HJm96KwQ== From: SJ Park To: SJ Park Cc: Andrew Morton , stable@vger.kernel.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/damon/core: handle region split failure in apply_min_nr_regions() Date: Sat, 18 Jul 2026 10:21:46 -0700 Message-ID: <20260718172147.87900-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260718163708.84113-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5802140007 X-Stat-Signature: rijrfkpnq5cunb8xeuxjkgm7t6msrmdu X-HE-Tag: 1784395318-134646 X-HE-Meta: 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 7U5UNLsW qERqeVzf2y+CDD3YwhTXpfqATCYXV8bNQ7AxO/IeTUeGwPzHVtbhCpAMxG7qKg6B7dbQXKRgLKimHbE0monbkZXRA6uEeQm+IMMN8D7fcMGbr7lf6i2dXmhr/tJop59e7K41fLJommutrF1pWYspU5xf934AVnpxFMWTITdHojJ5zWY7q9tp2rWmbbrbfXaaggVX1kiz31rI9IEIysY4L+37k98EsNCdRTPqf8qr9nHSLO9yujhx22VT1PTmEb89sIHfT6wepyNHemJofcNYsF8H88g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 18 Jul 2026 09:37:06 -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 a room to improve in this patch. I will post a new revision with the improvement. Please don't add this to mm-new. Thanks, SJ [...]