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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vdUqx-0000000DVit-44jG; Wed, 07 Jan 2026 14:49:40 +0000 Date: Wed, 7 Jan 2026 14:49:39 +0000 From: Matthew Wilcox To: =?utf-8?B?546L5b+X?= <23009200614@stu.xidian.edu.cn> Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, x86@kernel.org, paulmck@kernel.org, tglx@linutronix.de, peterz@infradead.org, akpm@linux-foundation.org, syzkaller-bugs@googlegroups.com Subject: Re: [BUG] rcu: stall detected in sys_mmap with PREEMPT(full) involving timer softirq and DRM vblank disable Message-ID: References: <6b7e2fac.a60e.19b97034116.Coremail.23009200614@stu.xidian.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6b7e2fac.a60e.19b97034116.Coremail.23009200614@stu.xidian.edu.cn> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7DFA920005 X-Stat-Signature: tj8zd7aas556gi4j68eqnfasan83hbjd X-HE-Tag: 1767797382-136636 X-HE-Meta: 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 WY/pdOHY d9oIg4ehCXQO+po0sc5kp/zFDWuDG4f9XCH0Tt00BMIt++pNYpeZnbbeNl+Xr1a46JXRLhoxJtruFBu4qEC85qYVCWrWp2RoN8vU0bb6NI1uXglaYu8isnCx22OfUdQBdxGy6nb49EdbV6t29pZoNpB+X3x9Fa9lWRxtDJL74kEks2hTdaAbFCRR5YCjzVri972R5vWctOGXm/QfNMKXtplsuZJLdZVDJ1tW/ujG8ipt22f+30rlUIgIQyapfVM9DY5DY9eka/+LDN9g/WVKDthKzDixrKNNV3ukIXTAcjv1wACLgPPq37Eh3iVNjSRLbih6/ 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 Wed, Jan 07, 2026 at 01:52:11PM +0800, 王志 wrote: > Hello, > > I am reporting an RCU stall detected during syzkaller-style fuzz testing. > The stall is reported while executing sys_mmap(), with the > rcu_preempt grace-period kthread starved for over 10 seconds. The > observed stacks involve memory fault handling, timer softirq processing, > and DRM vblank disable paths. With PREEMPT(full) enabled, the RCU grace > period fails to complete. Get your changes into syzkaller upstream, don't spam us with "i'm doing syzbot's job".