From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9246513D539; Wed, 7 Jan 2026 14:49:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767797384; cv=none; b=EOc7zidWeSSODQ1vsFhCxGU7TfwYXKumI82HNaOPXQf227u2qdn+ypKfxm666P+brYiqeOxJH9As5iBIPDLFjDWc9X92CazHuR1VrUAWO4YOaWIMw5Eos5iXZNNFj9TKKjiFy5cd6xeCf3GXRrlfg6zzA4qFODuKNew3t4Q4BzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767797384; c=relaxed/simple; bh=YI7mXRwYQgsZul98x1G9XIaZHQiOYlQEaaq+SdM5Ado=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t8l52kYfb6Ec9K5a+kbo4Pchg+dNTmj1xvskjOLtbEl9G+cewXSsIt7iz04nDbh3VYoZ6xT9xppTg2N3/NT5CNWzxL4DbrHi0WJQZN3oDrCuP15kYdb6nV5dmMYq6VCq1nVVcHCAyCiBNl35jZHfpLgSJzTzOAinq50G81mgpy8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=XmDC6RSj; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XmDC6RSj" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=l9zPldPO0gnPG9wqrGk15pRMXLG4lDUH1uQahecjpaw=; b=XmDC6RSjQjF/FBL9NZNvteRWSJ XfSf2hlRECEq0ebGyg5PpKJwJCMOSfzAKwNiq943mtTwN562XqVg6CXBQSWlSMPkQvBjMDvcHMIaq VbMaChEVW2NJrWYX+WTkUc4q69Qc5hAruLFHgmNhAYSWJ1vsrga7eXrkK796N4NMiipuPKZTZaOyY rFR/5UDT6V5KElXh5mZSYB1MBSII5ql1opBUYPQgnNho0fHqTuxPNBDc2lGvJn8XWN6B5G7rhA+bL 5Nr/2YPyuCjvtoxt9xu77oRYLe5AYcNt5uU3ZpPNrjBz5lS//E3QOZJVBGISdvCI/NU5j64SAazKq NN8VbQ0g==; 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> 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".