Messages in this thread | | | From | Dmitry Vyukov <> | Date | Mon, 2 Nov 2015 14:25:33 +0100 | Subject | WARNING in task_participate_group_stop |
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Hello,
I've hit the following WARNING on 6a13feb9c82803e2b815eca72fa7a9f5561d7861 (4.3)
------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at kernel/signal.c:334 task_participate_group_stop+0x157/0x1d0() Modules linked in: CPU: 1 PID: 1 Comm: init Not tainted 4.3.0 #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff82e40280 ffff88003eb0fae0 ffffffff819efe55 0000000000000000 ffff88003eb0fb20 ffffffff810ec871 ffffffff8110f4d7 ffff88003eb00000 ffff88003eb20000 0000000000000000 ffff88003eb0fbf8 ffff88003eb20000 Call Trace: [<ffffffff810eca35>] warn_slowpath_null+0x15/0x20 kernel/panic.c:480 [<ffffffff8110f4d7>] task_participate_group_stop+0x157/0x1d0 kernel/signal.c:334 [<ffffffff81113587>] do_signal_stop+0x1e7/0x6e0 kernel/signal.c:2060 [<ffffffff81116ab7>] get_signal+0x387/0x11b0 kernel/signal.c:2316 [<ffffffff8100cf0d>] do_signal+0x8d/0x19e0 arch/x86/kernel/signal.c:707 [<ffffffff81005d8d>] prepare_exit_to_usermode+0x11d/0x170 arch/x86/entry/common.c:251 [<ffffffff81005e83>] syscall_return_slowpath+0xa3/0x2b0 arch/x86/entry/common.c:317 [<ffffffff82d4f6a7>] int_ret_from_sys_call+0x25/0x8f arch/x86/entry/entry_64.S:281 ---[ end trace f6697fd630b7c361 ]---
The reproducer is (needs to be run as root):
// autogenerated by syzkaller (http://github.com/google/syzkaller) #include <sys/ptrace.h> #include <unistd.h>
int main() { int pid = 1; ptrace(PTRACE_ATTACH, pid, 0, 0); ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_EXITKILL); sleep(1); return 0; }
Yes, it is weird and it kills init right afterwards. But I wasn't able to figure out what's the root cause (why task does not have JOBCTL_STOP_PENDING) and maybe the same WARNING can be triggered without root and/or with other than init process. So still posting it here.
Can somebody more knowledgeable in ptrace please take a look at the root cause?
Thanks
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