From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753839AbdKAF4I (ORCPT ); Wed, 1 Nov 2017 01:56:08 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:54090 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274AbdKAF4H (ORCPT ); Wed, 1 Nov 2017 01:56:07 -0400 X-Google-Smtp-Source: ABhQp+Sr9dQTjJfRJcCpzsLdgbjbUg0+FG2XzvMICgZ82R8f/7O6MJ4GQzDgr9aUURJoyFn9LZYeDweJg8izhyz6+Pw= MIME-Version: 1.0 In-Reply-To: <20171031163451.GA30223@redhat.com> References: <94eb2c058c80ea49ed055cc8695e@google.com> <20171031163451.GA30223@redhat.com> From: Dmitry Vyukov Date: Wed, 1 Nov 2017 08:55:45 +0300 Message-ID: Subject: Re: WARNING in task_participate_group_stop To: Oleg Nesterov Cc: syzbot , Andrew Morton , Arvind Yadav , Mark Brown , "Eric W. Biederman" , =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , jamie.iles@oracle.com, LKML , "Martin K. Petersen" , mchehab@kernel.org, Ingo Molnar , mpe@ellerman.id.au, syzkaller-bugs@googlegroups.com, Al Viro Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 31, 2017 at 7:34 PM, Oleg Nesterov wrote: > On 10/30, Dmitry Vyukov wrote: >> >> On Mon, Oct 30, 2017 at 10:12 PM, syzbot >> >> wrote: >> > Hello, >> > >> > syzkaller hit the following crash on >> > d95e159cd1da1ed4dbf76bf203e8ffaf231395e4 >> > git://git.cmpxchg.org/linux-mmots.git/master >> > compiler: gcc (GCC) 7.1.1 20170620 >> > .config is attached >> > Raw console output is attached. >> > C reproducer is attached > > Hmm. I do not see reproducer in this email... Ah, sorry. You can see full thread with attachments here: https://groups.google.com/forum/#!topic/syzkaller-bugs/EUmYZU4m5gU >> > syzkaller reproducer is attached. See https://goo.gl/kgGztJ >> > for information about syzkaller reproducers >> >> This also happens on more recent commits, including linux-next >> 36ef71cae353f88fd6e095e2aaa3e5953af1685d (Oct 19) and upstream >> 3e0cc09a3a2c40ec1ffb6b4e12da86e98feccb11 (Oct 18). >> >> > WARNING: CPU: 0 PID: 1 at kernel/signal.c:340 >> > task_participate_group_stop+0x1ce/0x230 kernel/signal.c:340 >> > Kernel panic - not syncing: panic_on_warn set ... >> > >> > CPU: 0 PID: 1 Comm: init Not tainted 4.13.0-mm1+ #5 > > Looks familiar... I need some time to recall the details, will try to send > the fix(es) this week. > > So this is init process with SIGNAL_UNKILLABLE flag set. And I hope it has > the pending SIGKILL, otherwise there is something else. > > IIRC the problem is that complete_signal(SIGKILL) does nothing if > SIGNAL_UNKILLABLE is set, in particular it doesn't set SIGNAL_GROUP_EXIT. > This fools the signal_group_exit() check in do_signal_stop(). > > Actually there are more problems with SIGNAL_UNKILLABLE && SIGKILL, we need > some nasty cleanups. > > Oleg. > > >> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> > Google 01/01/2011 >> > Call Trace: >> > __dump_stack lib/dump_stack.c:16 [inline] >> > dump_stack+0x194/0x257 lib/dump_stack.c:52 >> > panic+0x1e4/0x417 kernel/panic.c:181 >> > __warn+0x1c4/0x1d9 kernel/panic.c:542 >> > report_bug+0x211/0x2d0 lib/bug.c:183 >> > fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178 >> > do_trap_no_signal arch/x86/kernel/traps.c:212 [inline] >> > do_trap+0x260/0x390 arch/x86/kernel/traps.c:261 >> > do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298 >> > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311 >> > invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905 >> > RIP: 0010:task_participate_group_stop+0x1ce/0x230 kernel/signal.c:340 >> > RSP: 0018:ffff8801d9ee77f0 EFLAGS: 00010097 >> > RAX: ffff8801d9ed8040 RBX: ffff8801d9ed8040 RCX: ffff8801d9edb2c0 >> > RDX: 0000000000000000 RSI: 0000000000060013 RDI: ffff8801d9ed84d0 >> > RBP: ffff8801d9ee7808 R08: ffff8801d9ee7180 R09: ffff8801d9ee7178 >> > R10: ffff8801d9ee70f0 R11: 1ffff1003b3db29b R12: ffff8801d9ee9740 >> > R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8801d9ed85c8 >> > do_signal_stop+0x217/0x900 kernel/signal.c:2042 >> > get_signal+0x61c/0x17e0 kernel/signal.c:2297 >> > do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808 >> > exit_to_usermode_loop+0x224/0x300 arch/x86/entry/common.c:158 >> > prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] >> > syscall_return_slowpath+0x42f/0x500 arch/x86/entry/common.c:266 >> > entry_SYSCALL_64_fastpath+0xbc/0xbe >> > RIP: 0033:0x7f33f723fdd3 >> > RSP: 002b:00007fffb5303398 EFLAGS: 00000246 ORIG_RAX: 0000000000000017 >> > RAX: fffffffffffffdfe RBX: 00007fffb5303540 RCX: 00007f33f723fdd3 >> > RDX: 0000000000000000 RSI: 00007fffb53036f0 RDI: 000000000000000b >> > RBP: 00007fffb53036f0 R08: 00007fffb5303770 R09: 0000000000000001 >> > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff >> > R13: 00007fffb5303ad0 R14: 0000000000000000 R15: 0000000000000000 >> > >> > >> > --- >> > This bug is generated by a dumb bot. It may contain errors. >> > See https://goo.gl/tpsmEJ for details. >> > Direct all questions to syzkaller@googlegroups.com. >> > >> > syzbot will keep track of this bug report. >> > Once a fix for this bug is committed, please reply to this email with: >> > #syz fix: exact-commit-title >> > To mark this as a duplicate of another syzbot report, please reply with: >> > #syz dup: exact-subject-of-another-report >> > If it's a one-off invalid bug report, please reply with: >> > #syz invalid >> > Note: if the crash happens again, it will cause creation of a new bug >> > report. >> > >> > -- >> > You received this message because you are subscribed to the Google Groups >> > "syzkaller-bugs" group. >> > To unsubscribe from this group and stop receiving emails from it, send an >> > email to syzkaller-bugs+unsubscribe@googlegroups.com. >> > To view this discussion on the web visit >> > https://groups.google.com/d/msgid/syzkaller-bugs/94eb2c058c80ea49ed055cc8695e%40google.com. >> > For more options, visit https://groups.google.com/d/optout. >