On Tue, Mar 31, 2020 at 3:28 PM syzbot <syzbot+0076781e1606f479425e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 770fbb32 Add linux-next specific files for 20200228 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1414f7ade00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=576314276bce4ad5 > dashboard link: https://syzkaller.appspot.com/bug?extid=0076781e1606f479425e > 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+0076781e1606f479425e@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > percpu ref (io_file_data_ref_zero) <= 0 (0) after switching to atomic Looking at this io_file_data_ref_zero, this seems to be io_uring related. +io_uring maintainers > WARNING: CPU: 0 PID: 0 at lib/percpu-refcount.c:160 percpu_ref_switch_to_atomic_rcu+0x436/0x540 lib/percpu-refcount.c:160 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x188/0x20d lib/dump_stack.c:118 > panic+0x2e3/0x75c kernel/panic.c:221 > __warn.cold+0x2f/0x35 kernel/panic.c:582 > report_bug+0x27b/0x2f0 lib/bug.c:195 > fixup_bug arch/x86/kernel/traps.c:175 [inline] > fixup_bug arch/x86/kernel/traps.c:170 [inline] > do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267 > do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 > invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 > RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x436/0x540 lib/percpu-refcount.c:160 > Code: 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 f7 00 00 00 49 8b 75 e8 4c 89 e2 48 c7 c7 e0 d1 71 88 e8 02 36 b5 fd <0f> 0b e9 2b fd ff ff e8 7e 6a e3 fd be 08 00 00 00 48 89 ef e8 51 > RSP: 0018:ffffc90000007df0 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: 0000000000000100 RSI: ffffffff815c4e91 RDI: fffff52000000fb0 > RBP: ffff88808c4b2810 R08: ffffffff8987a480 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: ffff88808c4b2838 R14: 0000000000000002 R15: 0000000000000007 > rcu_do_batch kernel/rcu/tree.c:2218 [inline] > rcu_core+0x59f/0x1370 kernel/rcu/tree.c:2445 > __do_softirq+0x26c/0x99d kernel/softirq.c:292 > invoke_softirq kernel/softirq.c:373 [inline] > irq_exit+0x192/0x1d0 kernel/softirq.c:413 > exiting_irq arch/x86/include/asm/apic.h:546 [inline] > smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1146 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 > </IRQ> > RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61 > Code: cc cc cc cc cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d e4 35 65 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d d4 35 65 00 fb f4 <c3> cc 41 56 41 55 41 54 55 53 e8 f3 25 9d f9 e8 8e f7 cf fb 0f 1f > RSP: 0018:ffffffff89807d98 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 > RAX: 1ffffffff132790a RBX: ffffffff8987a480 RCX: 0000000000000000 > RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff8987ad1c > RBP: dffffc0000000000 R08: ffffffff8987a480 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff130f490 > R13: 0000000000000000 R14: ffffffff8a862140 R15: 0000000000000000 > arch_safe_halt arch/x86/include/asm/paravirt.h:144 [inline] > default_idle+0x49/0x350 arch/x86/kernel/process.c:698 > cpuidle_idle_call kernel/sched/idle.c:154 [inline] > do_idle+0x393/0x690 kernel/sched/idle.c:269 > cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361 > start_kernel+0x867/0x8a1 init/main.c:1001 > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > 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@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000016bac605a2268a08%40google.com.
