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b=TLuqmX/pqFQ4BD7UUGrq4wDvvLzOgy+cEoJ1yiiSvfqGO/NRpbcCm5bPJzc/6ibuz wrEXi+kG3GfkyAzGC7N3ioZ+s9N0TslW9GMX6tcIkIn0GymjFJrdMNjvakRgyXcery 5g4sYF/iRu9uAfRr9DldP9smuzYaKUPp48SDBj3M= Date: Tue, 9 Apr 2024 16:46:27 -0700 From: Andrew Morton To: syzbot Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] general protection fault in hpage_collapse_scan_file Message-Id: <20240409164627.b4803e09c81c01ccb6f55601@linux-foundation.org> In-Reply-To: <0000000000009db84e0615a73698@google.com> References: <0000000000009db84e0615a73698@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4EA67180002 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 4xsmxmsikfn4en37w15aapzwzjk64rby X-HE-Tag: 1712706392-900991 X-HE-Meta: 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 kI8eN4nn 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 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: On Tue, 09 Apr 2024 03:16:20 -0700 syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 8568bb2ccc27 Add linux-next specific files for 20240405 > git tree: linux-next > console+strace: https://syzkaller.appspot.com/x/log.txt?x=152f4805180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=48ca5acf8d2eb3bc > dashboard link: https://syzkaller.appspot.com/bug?extid=57adb2a4b9d206521bc2 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1268258d180000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1256598d180000 Help. From a quick look this seems to be claiming that collapse_file() got to VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); with folio==NULL, but the code look solid regarding this. Given that we have a reproducer, can we expect the bot to perform a bisection for us?