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 C432D39A071 for ; Fri, 3 Jul 2026 09:48:10 +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=1783072094; cv=none; b=VDAKVKEf61qQrsc5Yyx2XVWl48AB/NJ6vd7B90I1rmQtmaDLOPQ+FEfl6ilVRnoMgAOHMGwGrUXXykqF3VyF8gdhmPSayIRhmx7pl+YDcf6YFGkVJsV0mzk9jKjjc2/6CumOfaLyyc7w3Y38bhr3wpRHUm1hCiOXy27l++wkMVo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783072094; c=relaxed/simple; bh=scaUVjLZh78BRfrM8I5JNotowPw6lhfruhSG42n5qVw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QH+YZtwZMqEpr8oS58sKUFa8cm3j0vIFZfbPkStheixeNZHuhgcFQOi7vGkln5+V4r5W/Ipa4p8YEHTkyHelklj4VGP+oA9TukM3Lnww4UCBFlstB2HyMhAm8TmkN5b3uu001PLLJIHgaLJmih0DUPfvIhC23UPD4ExFPvFxxxc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=BnOyNx9k; 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=pass 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="BnOyNx9k" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=0Yeysv9aKehsu7FHdkQjy10j7T+w5qldPUhsDizRfys=; b=BnOyNx9k/pslrzhoKBP+EOxG2x BJaSRFIk/1OPhCX+hUX2b/BfW4E/yhcAD8eW9ClKiVFCeQoLV5yoiX19FPKTcE+BOwdp0l0vf/FFb /tWc3h5peYkM9jYqTxUYR7A/FiWWUxDDXMIElo7G51kB6tlsyY8SgDo1DF3grK5aGVICEJ1YfLhZl cq7YgOWhX9AxefjKAwIiGyvciM+9f3qGTFZQe1RwL0SeSoSVvn62CVdzYfA6W5GzmTKnrFd+oONOR oSS94cv/6aBXzXFwkxIzG3qjNE8Q1Y3vku/Agq4mTADqO0IOH4Fx46bDD1OoBH1V2U2EPG04lJwt2 CHknwDPw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfaVA-0000000A6SJ-2RjW; Fri, 03 Jul 2026 09:48:04 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 54980300220; Fri, 03 Jul 2026 11:48:04 +0200 (CEST) Date: Fri, 3 Jul 2026 11:48:04 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: syzbot , bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, x86@kernel.org Subject: Re: [syzbot] [kernel?] WARNING in update_rq_clock (2) Message-ID: <20260703094804.GC651302@noisy.programming.kicks-ass.net> References: <6a470486.52c20a74.1f8b39.000c.GAE@google.com> <87fr20mmxx.ffs@fw13> 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=us-ascii Content-Disposition: inline In-Reply-To: <87fr20mmxx.ffs@fw13> On Fri, Jul 03, 2026 at 11:39:38AM +0200, Thomas Gleixner wrote: > On Thu, Jul 02 2026 at 17:38, syzbot wrote: > > CC+: Peter > > Dear syzbot folks. The selection of people you CC on your reports is > annoyingly random. The splat clearly says: > > > WARNING: kernel/sched/sched.h:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline], CPU#0: syz.4.1183/11558 > > So why not picking that up and: > > # scripts/get_maintainer.pl -f kernel/sched/sched.h > > Ingo Molnar (maintainer:SCHEDULER) > Peter Zijlstra (maintainer:SCHEDULER) > Juri Lelli (maintainer:SCHEDULER) > Vincent Guittot (maintainer:SCHEDULER) > Dietmar Eggemann (reviewer:SCHEDULER) > Steven Rostedt (reviewer:SCHEDULER) > Ben Segall (reviewer:SCHEDULER) > Mel Gorman (reviewer:SCHEDULER) > Valentin Schneider (reviewer:SCHEDULER) > K Prateek Nayak (reviewer:SCHEDULER) > linux-kernel@vger.kernel.org (open list:SCHEDULER) > > > ? > > Leaving the report untrimmed for Peter. > > > syzbot found the following issue on: > > > > HEAD commit: 8b69c0475871 Merge tag 'input-for-v7.2-rc0-2' of git://git.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=1196f4ea580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=eb3cf873145f98c4 > > dashboard link: https://syzkaller.appspot.com/bug?extid=681e729b2cf0d4860042 > > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/6fbba2b94559/disk-8b69c047.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/377e82061e2d/vmlinux-8b69c047.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/f299b46fb771/bzImage-8b69c047.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+681e729b2cf0d4860042@syzkaller.appspotmail.com > > > > ------------[ cut here ]------------ > > debug_locks && !(lock_is_held(&(__rq_lockp(rq))->dep_map) != 0) > > WARNING: kernel/sched/sched.h:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline], CPU#0: syz.4.1183/11558 > > WARNING: kernel/sched/sched.h:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline], CPU#0: syz.4.1183/11558 > > WARNING: kernel/sched/sched.h:1641 at update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865, CPU#0: syz.4.1183/11558 > > Modules linked in: > > CPU: 0 UID: 0 PID: 11558 Comm: syz.4.1183 Tainted: G U L syzkaller #0 PREEMPT(full) > > Tainted: [U]=USER, [L]=SOFTLOCKUP > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 > > RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline] > > RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1638 [inline] > > RIP: 0010:update_rq_clock+0x40a/0xd20 kernel/sched/core.c:865 > > Code: ab c8 0b 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d8 7e c8 09 a8 04 0f 84 df fc ff ff 90 0f 0b 90 e9 d6 fc ff ff 90 <0f> 0b 90 e9 92 fc ff ff 4c 8d 83 c0 0b 00 00 48 b8 00 00 00 00 00 > > RSP: 0018:ffffc90003cb70b8 EFLAGS: 00010046 > > RAX: 0000000000000000 RBX: ffff8880b853b600 RCX: 0000000000000001 > > RDX: 0000000000000046 RSI: ffffffff8df333b0 RDI: ffffffff8c1e8f80 > > RBP: ffffc90003cb7260 R08: 0000000000000001 R09: 0000000000000001 > > R10: ffffffff90dbdb97 R11: 0000000000000000 R12: ffffffff90dc0f44 > > R13: ffff8880b853c4e0 R14: ffff88801e6a1f00 R15: ffff8880b843c198 > > FS: 00007fece89b36c0(0000) GS:ffff8881242e7000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000000 CR3: 00000000775a2000 CR4: 00000000003526f0 > > Call Trace: > > > > pick_next_task kernel/sched/core.c:6338 [inline] > > __schedule+0x1e2d/0x6730 kernel/sched/core.c:7149 This doesn't really make sense, this is in SCHED_CORE's pick_next_task() restart_multi: loop. It does update_rq_clock() for all 'other' SMT siblings, and validates __rq_lockp(rq) is held, which it very much should be there. Given you don't have a reproducer, and the static lock context analysis code isn't complaining here, I'm rather suspect of the report and would not rule out random memory corruption. Anyway, if this persists and or a reproducer is found, I'm sure I'll look at it eventually.