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Wysocki" , Danilo Krummrich , Alexander Viro , Christian Brauner , Jan Kara , Ingo Molnar , Peter Zijlstra , Andrew Morton , Jens Axboe , driver-core@lists.linux.dev, autofs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+002fb7b2d0bc53bf7e75@syzkaller.appspotmail.com Subject: Re: [PATCH 0/2] kernfs, autofs: fix pipe lock cycles through sysfs stores In-Reply-To: References: <6aa23178.f81106d8.2ab401.0006.GAE@google.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8D51D18000C X-Stat-Signature: mgr7i4n3jkwxuyiyzomk5zk181kxcjim X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1792619306-42639 X-HE-Meta: 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 X0WMRHXc IO7I1cCEswrjcHNRr3VgTDlrdV+gBv4ekoU7V3K71nDREJjXAOHHfIJK7oml06DpYJ35FILZcSUaYdKAy2/RijmhpH1ipp1KM6p44qoYVY5mrlfkdBDvZiKSdnfsgeWcWN7CR8DBXIUret80DHBx1YzcN62u14WqyO1qz6RP73nz2PTX5aytPWDpftyqyA9ESgnHdlDCiI0769X5eAsYvYFZzSWJEN6xLD8hqdsZFUOTe1Iit0aNaF1NFTzDsBPrqZjRR16/Q5RBz99JpeFaIFVt3Z5OXXTY0kvjvrNYqJS+KVYRmOxP6MTuyzHLt/lSweZIFWkH7xrIIFB30q05do7VZwdRhaGz/DratrAn+OWgPdeEggZ5uR4uN71CvG2OZ+mVcQDqrXepnLdA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Hello, Krystian. On Wed, Oct 21, 2026 at 02:51:48PM +0200, Krystian Kaniewski wrote: > syzbot reports a lockdep cycle &pipe->mutex --> &of->mutex --> > &sbi->pipe_mutex. splice holds a pipe mutex while it calls the write or > read handler of a kernfs file, kernfs takes of->mutex there, and a write > to /sys/power/resume looks up a path that can make autofs write a request > into its daemon pipe and wait for the daemon. This is an extremely convoluted case that isn't going to happen in any realistic scenario, and it doesn't make sense to change the locking scheme for it. Can we just disallow splice on /sys/power/resume instead? Thanks. -- tejun