syzbot


INFO: rcu detected stall in sys_umount (2)

Status: auto-closed as invalid on 2022/06/20 00:56
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 256d, last: 256d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_umount 8 1227d 1231d 0/24 auto-closed as invalid on 2019/10/25 14:21

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (1 GPs behind) idle=539/1/0x4000000000000000 softirq=14197/14203 fqs=0 
	(t=13999 jiffies g=17013 q=1097)
rcu: rcu_preempt kthread starved for 13999 jiffies! g17013 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:26448 pid:   14 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:4995 [inline]
 __schedule+0x926/0x1080 kernel/sched/core.c:6304
 schedule+0x12b/0x1f0 kernel/sched/core.c:6377
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1881
 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1963
 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2136
 kthread+0x2a3/0x2d0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 5.17.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xc33/0xe10 kernel/smp.c:969
Code: 00 00 00 00 fc ff df 75 0e e8 99 bb 0b 00 eb 4c 0f 1f 80 00 00 00 00 f3 90 42 0f b6 04 3b 84 c0 75 11 41 f7 45 00 01 00 00 00 <74> 2b e8 76 bb 0b 00 eb e4 44 89 e9 80 e1 07 80 c1 03 38 c1 7c e2
RSP: 0018:ffffc90000cd7800 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 1ffff11017367f3d RCX: ffff888011fe5700
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000cd7940 R08: ffffffff8179de42 R09: ffffffff844e9880
R10: 0000000000000009 R11: ffff888011fe5700 R12: 0000000000000001
R13: ffff8880b9b3f9e8 R14: ffff8880b9a3a840 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0004193a6 CR3: 000000000c88e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1135
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1112 [inline]
 text_poke_bp_batch+0x309/0x920 arch/x86/kernel/alternative.c:1300
 text_poke_flush arch/x86/kernel/alternative.c:1470 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1477
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x12d/0x250 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 toggle_allocation_gate+0xbf/0x460 mm/kfence/core.c:735
 process_one_work+0x86c/0x1190 kernel/workqueue.c:2307
 worker_thread+0xab1/0x1300 kernel/workqueue.c:2454
 kthread+0x2a3/0x2d0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30
 </TASK>
NMI backtrace for cpu 1
CPU: 1 PID: 3621 Comm: syz-executor.5 Not tainted 5.17.0-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:88 [inline]
 dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x45f/0x490 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x22d/0x390 kernel/rcu/tree_stall.h:343
 print_cpu_stall kernel/rcu/tree_stall.h:604 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:688 [inline]
 rcu_pending kernel/rcu/tree.c:3919 [inline]
 rcu_sched_clock_irq+0x1df5/0x2b70 kernel/rcu/tree.c:2617
 update_process_times+0x197/0x200 kernel/time/timer.c:1785
 tick_sched_handle kernel/time/tick-sched.c:226 [inline]
 tick_sched_timer+0x27d/0x420 kernel/time/tick-sched.c:1428
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
 __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103
 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20
RIP: 0010:rcu_read_lock_sched_held+0xba/0x130 kernel/rcu/update.c:126
Code: 00 00 00 48 c7 04 24 0e 36 e0 45 49 c7 04 1e 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 44 24 48 75 6d 44 89 f8 48 8d 65 e0 <5b> 41 5c 41 5e 41 5f 5d c3 65 8b 05 8e 65 93 7e 41 bf 01 00 00 00
RSP: 0018:ffffc9000288fa68 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 1ffff92000511f40 RCX: 0000000080000001
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000288fa88 R08: dffffc0000000000 R09: fffffbfff1c00bfe
R10: fffffbfff1c00bfe R11: 0000000000000000 R12: 0000000000000002
R13: 1ffff92000511f64 R14: dffffc0000000000 R15: 0000000000000001
 trace_lock_acquire+0x59/0x190 include/trace/events/lock.h:13
 lock_acquire+0xa5/0x4d0 kernel/locking/lockdep.c:5610
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:268
 rcu_read_lock include/linux/rcupdate.h:694 [inline]
 mntput_no_expire+0xc3/0xfe0 fs/namespace.c:1199
 path_umount+0x1e0/0xfc0 fs/namespace.c:1793
 ksys_umount fs/namespace.c:1812 [inline]
 __do_sys_umount fs/namespace.c:1817 [inline]
 __se_sys_umount fs/namespace.c:1815 [inline]
 __x64_sys_umount+0x122/0x170 fs/namespace.c:1815
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fdaa01034b7
Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffab0d8ba8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 00000000000001c6 RCX: 00007fdaa01034b7
RDX: 000000000000000c RSI: 000000000000000a RDI: 00007fffab0d9d30
RBP: 00007fffab0d9d0c R08: 0000000000000000 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdaa015b1ea
R13: 00007fffab0d9d30 R14: 0000000000000001 R15: 00007fffab0d9d70
 </TASK>
----------------
Code disassembly (best guess), 6 bytes skipped:
   0:	df 75 0e             	fbstp  0xe(%rbp)
   3:	e8 99 bb 0b 00       	callq  0xbbba1
   8:	eb 4c                	jmp    0x56
   a:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  11:	f3 90                	pause
  13:	42 0f b6 04 3b       	movzbl (%rbx,%r15,1),%eax
  18:	84 c0                	test   %al,%al
  1a:	75 11                	jne    0x2d
  1c:	41 f7 45 00 01 00 00 	testl  $0x1,0x0(%r13)
  23:	00
* 24:	74 2b                	je     0x51 <-- trapping instruction
  26:	e8 76 bb 0b 00       	callq  0xbbba1
  2b:	eb e4                	jmp    0x11
  2d:	44 89 e9             	mov    %r13d,%ecx
  30:	80 e1 07             	and    $0x7,%cl
  33:	80 c1 03             	add    $0x3,%cl
  36:	38 c1                	cmp    %al,%cl
  38:	7c e2                	jl     0x1c

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2022/03/22 00:49 upstream f443e374ae13 e2d91b1d .config log report info INFO: rcu detected stall in sys_umount
* Struck through repros no longer work on HEAD.