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b=jlc/MYhgqv0aG6eZrLeWjZ0tGnGPoPIdODsxFIivW0bYt6AYdK2bLex3vnm6AV4g/ 2bbJrWeAAzG5la1V1pyrR5riJvL22ar2RA9dZ7q8HIhyujANPyWInu0x8J0ATpgGYb DaYBFTiK6CfRzIcqzo6d+5R3vCVcjJ1uXToY6GmAl4ccpTm4TPgA4JxveSHjjbP13b 45TMbSN9MeTPpZU4v2rZOXRPnCxAugYbjSEXckjdn3xjkvev94gQ+CTHuXpvIqYYc/ QFM/5ESkhGpbBJI/Uw8twuLfZ5nv6wNa6KPLAysDEhaQftWLTH5VbcptbAeuiTBvTn FdUlhV3yJ4ceQ== Message-ID: <674ddd6c-7854-4864-ac7c-df6823d3a37f@kernel.org> Date: Mon, 7 Sep 2026 14:27:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/3] mm: khugepaged: fix folio is used after folio_put/unlock() To: Vernon Yang , akpm@linux-foundation.org, ljs@kernel.org Cc: nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, zokeefe@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Vernon Yang References: <20260828055926.346744-1-vernon2gm@gmail.com> <20260828055926.346744-4-vernon2gm@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5209B180009 X-Stat-Signature: a9zyuiqycdyjxamxu6je947kwnqmqrzo X-Rspam-User: X-HE-Tag: 1788784035-984828 X-HE-Meta: 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 sow6ZZYa 97sFBhuHCP5dGUkyTvkvmyqBNnTUe3Kli8YuWiBUl91JLt81fAMmVqPKAU1AW4SPKLKhv8hYFAQEw1NyQ02KwZ/YMc+nIe/MLUhEbH7E53MUXF5sf6iGNYyrfAMwlg6Sw5xjckUwL5ElifKQ1ChUh7jbzGXvvgqTyeV1WGH0Zuv/R9isSp1B1UkERCey/mGX+z7cbRGul5ysrgR8fKzA2XhUtlqbF2CO7GCG3sbJ3omNNIvy6eqzXfb+Q6aqvADM6hWinHHwLdsmqXcDqWXy6Kf7HfUT9C8JzUVJnfrWkdBG80Pz3wXqSmrUQcKlfNkQHyJsXRNl2XceCDsByvHXkwdK/IFABBgYABtDsMhlIcTzVgaY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/28/26 07:59, Vernon Yang wrote: > From: Vernon Yang > > On the rollback path, folio_put() has already dropped the last reference > of new_folio. On the success path, new_folio is already unlocked and can > be freed concurrently. The trace_mm_khugepaged_collapse_file() is left > with a dangling folio pointer. > > So using the folio_pfn() before dropping the reference, closing > use-after-free window. > > Acked-by: Lorenzo Stoakes (ARM) > Fixes: 4c9473e87e75 ("mm/khugepaged: add tracepoint to collapse_file()") > Cc: stable@vger.kernel.org > Signed-off-by: Vernon Yang > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David