From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 267AEC2BBCA for ; Wed, 16 Dec 2020 20:56:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB815238EB for ; Wed, 16 Dec 2020 20:56:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729049AbgLPU4U (ORCPT ); Wed, 16 Dec 2020 15:56:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727037AbgLPU4U (ORCPT ); Wed, 16 Dec 2020 15:56:20 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17490C061794; Wed, 16 Dec 2020 12:55:40 -0800 (PST) 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=vyA4GqkbuOPJ0kE51LkK+fuqRgR4xg+ZNtUrpfeL2d8=; b=ripwhSiWanG7+V1PW+YSN34+R0 vO9BGGaMCZ+0oDRvyhUEWZ7ezO/vnUIGC/syxD9yp424VfW397Ne+Mnr/vHexfeoBwRAQOkzfF1X8 Jl6D+vXthAlFMzChnzrAKLcjhfWe8Yl689sSTtUK1gzeCgAnGit566sGDA0BHeOiD2n8d8iOFhnIx XlL/C/R9xfeom4zFujjtm8wxy/ppo2MgUfjOSvFY1AORFXxnNVpV8fPfSt0DKGQXbxnRRrgt/Cxx4 gKK8tV0MU503xfsce2+ZE/he96d10qY6zQhcIJRmYPTlJwenqrTJxdE+SLFllcYyjbwyVAxiIh/w8 gpZC6lYw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kpdpg-00086q-Ni; Wed, 16 Dec 2020 20:55:36 +0000 Date: Wed, 16 Dec 2020 20:55:36 +0000 From: Matthew Wilcox To: syzbot Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Subject: Re: WARNING: suspicious RCU usage in count Message-ID: <20201216205536.GX2443@casper.infradead.org> References: <0000000000009867cb05b699f5b6@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000009867cb05b699f5b6@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Dec 16, 2020 at 11:34:10AM -0800, syzbot wrote: > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+51ce7a5794c3b12a70d1@syzkaller.appspotmail.com > > ============================= > WARNING: suspicious RCU usage > 5.10.0-rc7-syzkaller #0 Not tainted > ----------------------------- > kernel/sched/core.c:7270 Illegal context switch in RCU-bh read-side critical section! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 0 > no locks held by udevd/9038. > > stack backtrace: > CPU: 3 PID: 9038 Comm: udevd Not tainted 5.10.0-rc7-syzkaller #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:118 > ___might_sleep+0x220/0x2b0 kernel/sched/core.c:7270 > count.constprop.0+0x164/0x270 fs/exec.c:449 > do_execveat_common+0x2fd/0x7c0 fs/exec.c:1893 > do_execve fs/exec.c:1983 [inline] > __do_sys_execve fs/exec.c:2059 [inline] > __se_sys_execve fs/exec.c:2054 [inline] > __x64_sys_execve+0x8f/0xc0 fs/exec.c:2054 > do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 This must be the victim of something else. There's no way this call trace took the RCU read lock.