syzbot


INFO: rcu detected stall in lo_ioctl (3)

Status: closed as invalid on 2022/02/08 10:00
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 337d, last: 333d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in lo_ioctl (2) 2 1089d 1089d 0/24 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in lo_ioctl 193 1604d 1804d 0/24 closed as dup on 2018/05/04 17:09

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10499 ticks this GP) idle=4bb/1/0x4000000000000000 softirq=107436/107445 fqs=5199 
	(t=10500 jiffies g=137869 q=1524)
NMI backtrace for cpu 0
CPU: 0 PID: 17374 Comm: syz-executor.4 Not tainted 5.16.0-rc7-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+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343
 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:711 [inline]
 rcu_pending kernel/rcu/tree.c:3878 [inline]
 rcu_sched_clock_irq.cold+0x5c/0x759 kernel/rcu/tree.c:2597
 update_process_times+0x16d/0x200 kernel/time/timer.c:1785
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 0f 1f 44 00 00 55 48 8b 74 24 08 48 89 fd 48 83 c7 18 e8 3e dc 15 f8 48 89 ef e8 f6 51 16 f8 e8 91 03 37 f8 fb bf 01 00 00 00 <e8> 46 1c 09 f8 65 8b 05 5f a1 bb 76 85 c0 74 02 5d c3 e8 7b 76 b9
RSP: 0018:ffffc9000494f6c8 EFLAGS: 00000206
RAX: 0000000004edded7 RBX: dffffc0000000000 RCX: 1ffffffff1fef716
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffffff8bd5c4b8 R08: 0000000000000001 R09: ffffffff8ff76a0f
R10: 0000000000000001 R11: 0000000000000001 R12: 1ffffffff1701e30
R13: ffff888077711d00 R14: ffffffff8bd5c4b8 R15: ffffc90003bafb28
 rwsem_down_write_slowpath+0x576/0x1110 kernel/locking/rwsem.c:1127
 __down_write_common kernel/locking/rwsem.c:1268 [inline]
 __down_write_common kernel/locking/rwsem.c:1265 [inline]
 __down_write kernel/locking/rwsem.c:1277 [inline]
 down_write+0x135/0x150 kernel/locking/rwsem.c:1524
 kernfs_drain fs/kernfs/dir.c:486 [inline]
 __kernfs_remove+0x57e/0xab0 fs/kernfs/dir.c:1351
 kernfs_remove_by_name_ns+0x4f/0xa0 fs/kernfs/dir.c:1544
 kernfs_remove_by_name include/linux/kernfs.h:570 [inline]
 remove_files+0x96/0x1c0 fs/sysfs/group.c:28
 sysfs_remove_group+0x87/0x170 fs/sysfs/group.c:288
 loop_sysfs_exit drivers/block/loop.c:743 [inline]
 __loop_clr_fd+0xb25/0x1070 drivers/block/loop.c:1148
 loop_clr_fd drivers/block/loop.c:1237 [inline]
 lo_ioctl+0x398/0x17c0 drivers/block/loop.c:1562
 blkdev_ioctl+0x37a/0x800 block/ioctl.c:609
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f86427ccc57
Code: 3c 1c 48 f7 d8 49 39 c4 72 b8 e8 04 54 02 00 85 c0 78 bd 48 83 c4 08 4c 89 e0 5b 41 5c c3 0f 1f 44 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8641141f88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f86427ccc57
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000006
RBP: 00007f86411426bc R08: 00007f8641142020 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 000000000000000d R14: 00007f8641141fe0 R15: 0000000020000500
 </TASK>
----------------
Code disassembly (best guess):
   0:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
   5:	55                   	push   %rbp
   6:	48 8b 74 24 08       	mov    0x8(%rsp),%rsi
   b:	48 89 fd             	mov    %rdi,%rbp
   e:	48 83 c7 18          	add    $0x18,%rdi
  12:	e8 3e dc 15 f8       	callq  0xf815dc55
  17:	48 89 ef             	mov    %rbp,%rdi
  1a:	e8 f6 51 16 f8       	callq  0xf8165215
  1f:	e8 91 03 37 f8       	callq  0xf83703b5
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 46 1c 09 f8       	callq  0xf8091c75 <-- trapping instruction
  2f:	65 8b 05 5f a1 bb 76 	mov    %gs:0x76bba15f(%rip),%eax        # 0x76bba195
  36:	85 c0                	test   %eax,%eax
  38:	74 02                	je     0x3c
  3a:	5d                   	pop    %rbp
  3b:	c3                   	retq
  3c:	e8                   	.byte 0xe8
  3d:	7b 76                	jnp    0xb5
  3f:	b9                   	.byte 0xb9

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2021/12/28 18:16 upstream a8ad9a2434dc 76c8cf06 .config log report info INFO: rcu detected stall in lo_ioctl
ci-upstream-kasan-gce-smack-root 2021/12/23 22:02 upstream 76657eaef4a7 6caa12e4 .config log report info INFO: rcu detected stall in lo_ioctl
* Struck through repros no longer work on HEAD.