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=-0.7 required=3.0 tests=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 F08B3C433DF for ; Thu, 28 May 2020 13:33:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D58B320721 for ; Thu, 28 May 2020 13:33:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390465AbgE1Ndx (ORCPT ); Thu, 28 May 2020 09:33:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390303AbgE1Ndv (ORCPT ); Thu, 28 May 2020 09:33:51 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 902F5C05BD1E for ; Thu, 28 May 2020 06:33:51 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jeIfJ-0000NE-Fp; Thu, 28 May 2020 15:33:45 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id CB87F100D01; Thu, 28 May 2020 15:33:44 +0200 (CEST) From: Thomas Gleixner To: syzbot Cc: Paolo Bonzini , "Paul E. McKenney" , bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, luto@kernel.org, mingo@kernel.org, syzkaller-bugs@googlegroups.com, x86@kernel.org Subject: Re: WARNING: suspicious RCU usage in idtentry_exit In-Reply-To: <000000000000840d4d05a6850c73@google.com> References: <000000000000840d4d05a6850c73@google.com> Date: Thu, 28 May 2020 15:33:44 +0200 Message-ID: <87wo4wnpzb.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot writes: + Paolo, Paul > syzbot found the following crash on: > > HEAD commit: 7b4cb0a4 Add linux-next specific files for 20200525 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=13356016100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=47b0740d89299c10 > dashboard link: https://syzkaller.appspot.com/bug?extid=3ae5eaae0809ee311e75 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+3ae5eaae0809ee311e75@syzkaller.appspotmail.com > > ============================= > WARNING: suspicious RCU usage > 5.7.0-rc7-next-20200525-syzkaller #0 Not tainted > ----------------------------- > kernel/rcu/tree.c:715 RCU dynticks_nesting counter underflow/zero!! > > other info that might help us debug this: > > > RCU used illegally from idle CPU! > rcu_scheduler_active = 2, debug_locks = 1 > RCU used illegally from extended quiescent state! > no locks held by syz-executor.5/24641. > > stack backtrace: > CPU: 1 PID: 24641 Comm: syz-executor.5 Not tainted 5.7.0-rc7-next-20200525-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x18f/0x20d lib/dump_stack.c:118 > rcu_irq_exit_preempt+0x1fa/0x250 kernel/rcu/tree.c:715 > idtentry_exit+0x9e/0xc0 arch/x86/entry/common.c:583 > exc_general_protection+0x23d/0x520 arch/x86/kernel/traps.c:506 > asm_exc_general_protection+0x1e/0x30 arch/x86/include/asm/idtentry.h:353 > RIP: 0010:kvm_fastop_exception+0xb68/0xfe8 > Code: f2 ff ff ff 48 31 db e9 fb c9 2a f9 b8 f2 ff ff ff 48 31 f6 e9 ff c9 2a f9 31 c0 e9 ec 2c 2b f9 b8 fb ff ff ff e9 13 a9 31 f9 fb ff ff ff 31 c0 31 d2 e9 33 a9 31 f9 31 db e9 2a 0b 42 f9 31 > RSP: 0018:ffffc90004a87a30 EFLAGS: 00010212 > RAX: 0000000000040000 RBX: ffff88809cca4080 RCX: 0000000000000122 > RDX: 00000000000063ff RSI: ffffc90004a87a98 RDI: 0000000000000122 > RBP: 0000000000000122 R08: ffff888058486480 R09: fffffbfff131f481 > R10: ffffffff898fa403 R11: fffffbfff131f480 R12: 0000000000000122 > R13: 0000000000000078 R14: 0000000000000006 R15: ffffffff88244b5c > paravirt_read_msr_safe arch/x86/include/asm/paravirt.h:178 [inline] > vmx_create_vcpu+0x184/0x2b40 arch/x86/kvm/vmx/vmx.c:6827 > kvm_arch_vcpu_create+0x6a8/0xb30 arch/x86/kvm/x86.c:9427 > kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:3043 [inline] > kvm_vm_ioctl+0x15b7/0x2460 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3603 > vfs_ioctl fs/ioctl.c:48 [inline] > ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 > __do_sys_ioctl fs/ioctl.c:762 [inline] > __se_sys_ioctl fs/ioctl.c:760 [inline] > __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 > do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:353 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x45ca29 > Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f2c93b11c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00000000004e73c0 RCX: 000000000045ca29 > RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000004 > RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > R13: 0000000000000396 R14: 00000000004c62c6 R15: 00007f2c93b126d4 Weird. I have no idea how that thing is an EQS here. Thanks, tglx