Messages in this thread | | | Date | Tue, 31 Oct 2017 17:34:51 +0100 | From | Oleg Nesterov <> | Subject | Re: WARNING in task_participate_group_stop |
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On 10/30, Dmitry Vyukov wrote: > > On Mon, Oct 30, 2017 at 10:12 PM, syzbot > <bot+c9f0eb0d2a5576ece331a767528e6b52b4ff1815@syzkaller.appspotmail.com> > 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...
> > 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.
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