Messages in this thread | | | From | Dmitry Vyukov <> | Date | Tue, 3 Dec 2019 09:38:22 +0100 | Subject | Re: INFO: rcu detected stall in sys_kill |
| |
On Tue, Dec 3, 2019 at 9:27 AM syzbot <syzbot+de8d933e7d153aa0c1bb@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 596cf45c Merge branch 'akpm' (patches from Andrew) > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=15f11c2ae00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9bbcda576154a4b4 > dashboard link: https://syzkaller.appspot.com/bug?extid=de8d933e7d153aa0c1bb > compiler: clang version 9.0.0 (/home/glider/llvm/clang > 80fee25776c2fb61e74c1ecb1a523375c2500b69) > > 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+de8d933e7d153aa0c1bb@syzkaller.appspotmail.com
Something seriously broken in smack+kasan+vmap stacks, we now have 60 rcu stalls all over the place and counting. This is one of the samples. I've duped 2 other samples to this one, you can see them on the dashboard: https://syzkaller.appspot.com/bug?extid=de8d933e7d153aa0c1bb
I see 2 common this across all stalls: 1. They all happen on the instance that uses smack (which is now effectively dead), see smack instance here: https://syzkaller.appspot.com/upstream 2. They all contain this frame in the stack trace: free_thread_stack+0x168/0x590 kernel/fork.c:280 The last commit that touches this file is "fork: support VMAP_STACK with KASAN_VMALLOC". That may be very likely the root cause. +Daniel
> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: > (detected by 1, t=10502 jiffies, g=6629, q=331) > rcu: All QSes seen, last rcu_preempt kthread activity 10503 > (4294953794-4294943291), jiffies_till_next_fqs=1, root ->qsmask 0x0 > syz-executor.0 R running task 24648 8293 8292 0x0000400a > Call Trace: > <IRQ> > sched_show_task+0x40f/0x560 kernel/sched/core.c:5954 > print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline] > check_cpu_stall kernel/rcu/tree_stall.h:538 [inline] > rcu_pending kernel/rcu/tree.c:2827 [inline] > rcu_sched_clock_irq+0x1861/0x1ad0 kernel/rcu/tree.c:2271 > update_process_times+0x12d/0x180 kernel/time/timer.c:1726 > tick_sched_handle kernel/time/tick-sched.c:167 [inline] > tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 > __run_hrtimer kernel/time/hrtimer.c:1514 [inline] > __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 > hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] > smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 > </IRQ> > RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline] > RIP: 0010:check_kcov_mode kernel/kcov.c:70 [inline] > RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x50 kernel/kcov.c:102 > Code: cc 07 48 89 de e8 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 > c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c <8b> 91 80 13 00 > 00 83 fa 02 75 21 48 8b 91 88 13 00 00 48 8b 32 48 > RSP: 0018:ffffc900021c7c28 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 > RAX: ffffffff81487433 RBX: 0000000000000000 RCX: ffff88809428a100 > RDX: 0000000000000001 RSI: 00000000fffffffc RDI: ffffea0002479240 > RBP: ffffc900021c7c50 R08: dffffc0000000000 R09: fffffbfff1287025 > R10: fffffbfff1287025 R11: 0000000000000000 R12: dffffc0000000000 > R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff888091c57428 > free_thread_stack+0x168/0x590 kernel/fork.c:280 > release_task_stack kernel/fork.c:440 [inline] > put_task_stack+0xa3/0x130 kernel/fork.c:451 > finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 > context_switch kernel/sched/core.c:3388 [inline] > __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 > preempt_schedule_common kernel/sched/core.c:4236 [inline] > preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261 > ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 > __raw_read_unlock include/linux/rwlock_api_smp.h:227 [inline] > _raw_read_unlock+0x3a/0x40 kernel/locking/spinlock.c:255 > kill_something_info kernel/signal.c:1586 [inline] > __do_sys_kill kernel/signal.c:3640 [inline] > __se_sys_kill+0x5e9/0x6c0 kernel/signal.c:3634 > __x64_sys_kill+0x5b/0x70 kernel/signal.c:3634 > do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x422a17 > Code: 44 00 00 48 c7 c2 d4 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e > 0f 1f 84 00 00 00 00 00 0f 1f 40 00 b8 3e 00 00 00 0f 05 <48> 3d 01 f0 ff > ff 0f 83 dd 32 ff ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007fff38dca538 EFLAGS: 00000293 ORIG_RAX: 000000000000003e > RAX: ffffffffffffffda RBX: 0000000000000064 RCX: 0000000000422a17 > RDX: 0000000000000bb8 RSI: 0000000000000009 RDI: 00000000fffffffe > RBP: 0000000000000002 R08: 0000000000000001 R09: 0000000001c62940 > R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000008 > R13: 00007fff38dca570 R14: 000000000000f0b6 R15: 00007fff38dca580 > rcu: rcu_preempt kthread starved for 10533 jiffies! g6629 f0x2 > RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 > rcu: RCU grace-period kthread stack dump: > rcu_preempt R running task 29032 10 2 0x80004008 > Call Trace: > context_switch kernel/sched/core.c:3388 [inline] > __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 > schedule+0x181/0x210 kernel/sched/core.c:4155 > schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 > rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] > rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 > kthread+0x332/0x350 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > > --- > 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@googlegroups.com. > > 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@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000036decf0598c8762e%40google.com.
| |