From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 B787642AAF; Fri, 14 Feb 2025 10:20:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739528406; cv=none; b=WDVipCYyUqj63RJGrAzNhMZ6RPAb6Yf7gUwMx+4HJKikZVt7GYTQXRFRRcXl/8D9ct7U7nrP+O5citpEEx51YswOmxH3JT0R7GDpkwIb13Svl13tWGeN7ROlhpcN9COwbc4Z1isAc+IT4qX9+6H1pvEeLA554k14yOm+LM0Qc5g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739528406; c=relaxed/simple; bh=kfMj4c6O3tWgc6ztXJvVUog3WM88q7v0yQVPPXUMeFw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AXwaga/woPM31t5tnGnh9P397f7oJBwfGYE3pxDoUK06pmIFG671qgb06Ea0WQqblOowr88Ly6Q4watyWogpAaYA5OWiWMcGZSpOHSqjoRlDMjyj7h4h83rrRwQU4VVpxo6Mi+lw9wHQ1ze1pjsFrpnBGaWyvFKzsOi4KIXcQa4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=A+Nbgz9k; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="A+Nbgz9k" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=cpfkoDvOz4Ksm3PzH+IRQujrKVmY4HveZdCkzBUmOg0=; b=A+Nbgz9kuBQAaQFsIKUsf02sjO HjM/VOEHxZID581T0CJI6hOBcOB5coIf0rzD9GzM4wWeTUooBC1RoOjxBQ/s4D+csj1rQUVxXFZff Hiy/xcI7lbIaJNBBYgk51xmRRFn5l/OOOXG9SzWiXSToedEuLapQ6KzSqaoUUTIsdR9/wB0LKkWji zpeLYVeho/7R6Lq3AAibZ5ArRly0msBjVzjy8Csdf0OeS1hjwecfy6dRlc13Nl78sG+ua1ikT+QZ9 E19gigOuUAP9ztHs3RM7FfU33KqN6G0qEK4NXrColSifQrcwKxy3fEN9kaPJ/gz63N5IWyfbpfKM/ bN+DH67Q==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tisng-00000001EI7-3jOw; Fri, 14 Feb 2025 10:20:01 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id C2E3930050D; Fri, 14 Feb 2025 11:19:59 +0100 (CET) Date: Fri, 14 Feb 2025 11:19:59 +0100 From: Peter Zijlstra To: Waiman Long Cc: syzbot , cgroups@vger.kernel.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, mkoutny@suse.com, syzkaller-bugs@googlegroups.com, tj@kernel.org Subject: Re: [syzbot] [cgroups?] possible deadlock in __run_timer_base (2) Message-ID: <20250214101959.GH21726@noisy.programming.kicks-ass.net> References: <67a9136a.050a0220.110943.001e.GAE@google.com> <2aaa1663-fa9c-43ce-9421-60019899bac1@redhat.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2aaa1663-fa9c-43ce-9421-60019899bac1@redhat.com> On Tue, Feb 11, 2025 at 09:14:12PM -0500, Waiman Long wrote: > On 2/9/25 3:43 PM, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.ker.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=179453df980000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=1909f2f0d8e641ce > > dashboard link: https://syzkaller.appspot.com/bug?extid=ed801a886dfdbfe7136d > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-92514ef2.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/c4d8b91f8769/vmlinux-92514ef2.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/c24ec4365966/bzImage-92514ef2.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+ed801a886dfdbfe7136d@syzkaller.appspotmail.com > > This problem should be fixed by the following upstream patch once it is > merged into mainline. > > https://lore.kernel.org/lkml/20250127013127.3913153-1-longman@redhat.com/ > AFAICT all these lockdep reports are because of an earlier warning. Fix warning, report goes away. Notably: > > _printk+0xd5/0x120 kernel/printk/printk.c:2457 > > __report_bug lib/bug.c:195 [inline] > > report_bug+0x346/0x500 lib/bug.c:219 > > handle_bug+0x60/0x90 arch/x86/kernel/traps.c:285 > > exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:309 > > asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:621 > > expire_timers kernel/time/timer.c:1827 [inline] IOW I think we're focusing on the wrong thing here. > Peter, are you planning to merge this patch? This is another instance where > the old way of calling wake_up_process() inside the lock critical region can > lead to deadlock. I still don't love the Changelog, but yeah, I suppose I can pick it up. But I see Boqun took it and I'll get it eventually. No real hurry there I suppose.