syzbot


INFO: rcu detected stall in __mnt_want_write

Status: auto-closed as invalid on 2022/07/18 08:06
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 221d, last: 221d

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10499 ticks this GP) idle=267/1/0x4000000000000000 softirq=129938/129938 fqs=5114 
	(t=10500 jiffies g=204697 q=572)
NMI backtrace for cpu 0
CPU: 0 PID: 24507 Comm: syz-executor.0 Not tainted 5.18.0-rc3-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+0x1e6/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x262/0x3f0 kernel/rcu/tree_stall.h:343
 print_cpu_stall kernel/rcu/tree_stall.h:639 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:723 [inline]
 rcu_pending kernel/rcu/tree.c:3923 [inline]
 rcu_sched_clock_irq.cold+0xa1/0x8d6 kernel/rcu/tree.c:2625
 update_process_times+0x16d/0x200 kernel/time/timer.c:1788
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:243
 tick_sched_timer+0xee/0x120 kernel/time/tick-sched.c:1473
 __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:645
RIP: 0010:__mnt_want_write+0xdd/0x2e0 fs/namespace.c:348
Code: 00 02 00 00 89 de e8 02 83 9d ff 85 db 74 42 48 b8 00 00 00 00 00 fc ff df 4d 89 ec 49 c1 ec 03 49 01 c4 e8 c5 80 9d ff f3 90 <41> 0f b6 04 24 84 c0 74 08 3c 03 0f 8e 99 01 00 00 8b 5d 10 31 ff
RSP: 0018:ffffc9000a6a7a10 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000000000
RDX: ffff88801e3d1d00 RSI: ffffffff81db98ab RDI: 0000000000000003
RBP: ffff88804dfaa920 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81db98d0 R11: 0000000000000001 R12: ffffed1009bf5526
R13: ffff88804dfaa930 R14: ffff88804dfaa950 R15: ffff88805531e580
 do_dentry_open+0xb6a/0x11e0 fs/open.c:793
 do_open fs/namei.c:3476 [inline]
 path_openat+0x1c71/0x2910 fs/namei.c:3609
 do_filp_open+0x1aa/0x400 fs/namei.c:3636
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1213
 do_sys_open fs/open.c:1229 [inline]
 __do_sys_openat fs/open.c:1245 [inline]
 __se_sys_openat fs/open.c:1240 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1240
 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: 0033:0x7f7cc72890e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007f7cc8430168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7cc739bf60 RCX: 00007f7cc72890e9
RDX: 0000000000000002 RSI: 0000000020000340 RDI: 000000000000004e
RBP: 00007f7cc72e308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7cc78cfb1f R14: 00007f7cc8430300 R15: 0000000000022000
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 02                	add    %al,(%rdx)
   2:	00 00                	add    %al,(%rax)
   4:	89 de                	mov    %ebx,%esi
   6:	e8 02 83 9d ff       	callq  0xff9d830d
   b:	85 db                	test   %ebx,%ebx
   d:	74 42                	je     0x51
   f:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  16:	fc ff df
  19:	4d 89 ec             	mov    %r13,%r12
  1c:	49 c1 ec 03          	shr    $0x3,%r12
  20:	49 01 c4             	add    %rax,%r12
  23:	e8 c5 80 9d ff       	callq  0xff9d80ed
  28:	f3 90                	pause
* 2a:	41 0f b6 04 24       	movzbl (%r12),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	74 08                	je     0x3b
  33:	3c 03                	cmp    $0x3,%al
  35:	0f 8e 99 01 00 00    	jle    0x1d4
  3b:	8b 5d 10             	mov    0x10(%rbp),%ebx
  3e:	31 ff                	xor    %edi,%edi

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce 2022/04/19 08:01 upstream b2d229d4ddb1 8bcc32a6 .config log report info INFO: rcu detected stall in __mnt_want_write
* Struck through repros no longer work on HEAD.