From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout3.samsung.com (mailout3.samsung.com [203.254.224.33]) (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 4BBB5220F57 for ; Wed, 6 Aug 2025 08:18:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.33 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754468338; cv=none; b=nMbdBy3/scljcVmAPpky0dBnvTLU02HxTupZgH40EXcIZIa8FKWNIe0r6TdfWDlxXwEtigLV4disp/c/UEKaBAOMwBYirhQdGwAJs90fDejQbZWE33E0abHQtnckPBTIjfIg8tXajb0Qu51JG8NbJGuOdOFhB7/+3d6ue6ilqto= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754468338; c=relaxed/simple; bh=ZIa5n0ySCAvxtZj25PvsitxDDytszLcXX9XdQwpFFD4=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:In-Reply-To: Content-Type:References; b=lje+I9fOKWf/fSFFJ9gpeTj693Zqexc5VUscXL4PLYxE/SpvTpYMH/edZUv+w7o3HSTLGW1bcUjj5nFKnRBYXd9heBj61FetduT62KK8VT1LLqv9t8H2p6z2MB+AWRdMG8JAjBvQAbn/aOh0HPyE55UtLyNiq+AsuDx3yksdv2E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=l05xR5Xp; arc=none smtp.client-ip=203.254.224.33 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="l05xR5Xp" Received: from epcas2p4.samsung.com (unknown [182.195.41.56]) by mailout3.samsung.com (KnoxPortal) with ESMTP id 20250806081854epoutp0373cb54d4cf52109274af0e4a32154b9b~ZH6eGLSVW0653906539epoutp03I for ; Wed, 6 Aug 2025 08:18:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout3.samsung.com 20250806081854epoutp0373cb54d4cf52109274af0e4a32154b9b~ZH6eGLSVW0653906539epoutp03I DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1754468334; bh=TP9U+FTa/OPLUCiQ88VrRIyaA5FnNTXTszGwRphWeRg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=l05xR5Xp1gy1BbDUV+quRdPBkYR0lLsMliFmRb6mAtPDenKzvham0CTRSG5J/VOS6 1GyngqHOgmvu0rntdRJYWfoxIWfSDdV83pA3xMIiuyaZMWj0InD+wkyU38Kp58tew9 hqP112/W3mmvKVG2nqiAVT/bVt91vvC87RnaDl2w= Received: from epsnrtp03.localdomain (unknown [182.195.42.155]) by epcas2p1.samsung.com (KnoxPortal) with ESMTPS id 20250806081853epcas2p162cf960f7815b74e4dd14d2025e37367~ZH6dYkI6A2204222042epcas2p1e; Wed, 6 Aug 2025 08:18:53 +0000 (GMT) Received: from epcas2p3.samsung.com (unknown [182.195.36.91]) by epsnrtp03.localdomain (Postfix) with ESMTP id 4bxjqd0gLCz3hhT9; Wed, 6 Aug 2025 08:18:53 +0000 (GMT) Received: from epsmtip2.samsung.com (unknown [182.195.34.31]) by epcas2p3.samsung.com (KnoxPortal) with ESMTPA id 20250806081852epcas2p31662b77b33cb6ade6f7a5e85d53d6865~ZH6ce9IHs2605426054epcas2p3h; Wed, 6 Aug 2025 08:18:52 +0000 (GMT) Received: from perf (unknown [10.229.95.91]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250806081852epsmtip2cf9190be67158c0248f7c69a11eef8bb~ZH6cbiB2B0717007170epsmtip2o; Wed, 6 Aug 2025 08:18:52 +0000 (GMT) Date: Wed, 6 Aug 2025 17:24:02 +0900 From: Youngmin Nam To: Joel Fernandes Cc: paulmck@kernel.org, syzbot , jiangshanlai@gmail.com, josh@joshtriplett.org, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, rcu@vger.kernel.org, rostedt@goodmis.org, syzkaller-bugs@googlegroups.com, youngmin.nam@samsung.com, joonki.min@samsung.com, jkkkkk.choi@samsung.com, d7271.choe@samsung.com Subject: Re: [syzbot] [rcu?] WARNING in srcu_invoke_callbacks (2) Message-ID: Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <2c367857-e1a5-4235-94f4-724441e94968@nvidia.com> X-CMS-MailID: 20250806081852epcas2p31662b77b33cb6ade6f7a5e85d53d6865 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----pvtuYNBH3nxDMAsWpkvaC3wqZGu-8cOxHg_F0zl5WTIHs9AT=_112ad9_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P cpgsPolicy: CPGSC10-234,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250806081852epcas2p31662b77b33cb6ade6f7a5e85d53d6865 References: <67b4c7af.050a0220.14d86d.000a.GAE@google.com> <20250219132538.GA468969@joelnvbox> <27f4ffbe-2342-484d-9924-716a799b265f@paulmck-laptop> <2c367857-e1a5-4235-94f4-724441e94968@nvidia.com> ------pvtuYNBH3nxDMAsWpkvaC3wqZGu-8cOxHg_F0zl5WTIHs9AT=_112ad9_ Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Disposition: inline On Wed, Feb 19, 2025 at 10:09:06AM -0500, Joel Fernandes wrote: > > > On 2/19/2025 8:58 AM, Paul E. McKenney wrote: > > On Wed, Feb 19, 2025 at 08:25:38AM -0500, Joel Fernandes wrote: > >> On Tue, Feb 18, 2025 at 09:47:27AM -0800, syzbot wrote: > >>> Hello, > >>> > >>> syzbot found the following issue on: > >>> > >>> HEAD commit: a64dcfb451e2 Linux 6.14-rc2 > >>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci > >>> console output: https://syzkaller.appspot.com/x/log.txt?x=12398f18580000 > >>> kernel config: https://syzkaller.appspot.com/x/.config?x=c9c47badcd079906 > >>> dashboard link: https://syzkaller.appspot.com/bug?extid=ae5b16688c0c675b1a1f > >>> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > >>> userspace arch: arm64 > >>> > >>> Unfortunately, I don't have any reproducer for this issue yet. > >>> > >>> Downloadable assets: > >>> disk image: https://storage.googleapis.com/syzbot-assets/c0a862fcec77/disk-a64dcfb4.raw.xz > >>> vmlinux: https://storage.googleapis.com/syzbot-assets/f03793fc001b/vmlinux-a64dcfb4.xz > >>> kernel image: https://storage.googleapis.com/syzbot-assets/ae71c33eae14/Image-a64dcfb4.gz.xz > >>> > >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: > >>> Reported-by: syzbot+ae5b16688c0c675b1a1f@syzkaller.appspotmail.com > >>> > >>> ------------[ cut here ]------------ > >>> WARNING: CPU: 0 PID: 6430 at kernel/rcu/srcutree.c:1798 srcu_invoke_callbacks+0x368/0x3d8 > >> > >> This is weird, happens to be WARN_ON_ONCE(ready_cbs.len); in > >> srcu_invoke_callbacks(). > > > > Thank you for tracking that down! > > Sure! > > >> Perhaps, stack corruption or the SRCU cblist's ->seglen got corrupted? > > > > That has been the usual cause. And a double call_srcu() is a common > > cause of ->cblist corruption. We have CONFIG_DEBUG_OBJECTS_RCU_HEAD=y > > set up for SRCU as well as for RCU, it appears, so perhaps retry with > > that should this ever become reproducible? > Makes sense, will keep an eye out for it! > > thanks, > > - Joel > Hello all, syzbot reports that this issue is still occurring on recent kernels, for example 6.16 (see https://syzkaller.appspot.com/bug?extid=ae5b16688c0c675b1a1f). And the "CONFIG_DEBUG_OBJECTS_RCU_HEAD=y" has been set as well. (see https://syzkaller.appspot.com/text?tag=KernelConfig&x=dcbf08d90aa89bca) But there were no logs related with double call_srcu(). (see https://syzkaller.appspot.com/text?tag=CrashLog&x=13e40434580000) Unfortunately we don’t yet have a simple reproducer to reliably trigger the warning. Could you please advise whether a patch for this has already landed in mainline, or suggest any additional methods we could use to further validate and test it? Thanks. Youngmin ------pvtuYNBH3nxDMAsWpkvaC3wqZGu-8cOxHg_F0zl5WTIHs9AT=_112ad9_ Content-Type: text/plain; charset="utf-8" ------pvtuYNBH3nxDMAsWpkvaC3wqZGu-8cOxHg_F0zl5WTIHs9AT=_112ad9_--