syzbot


INFO: task hung in __fdget_pos (3)

Status: auto-closed as invalid on 2022/01/07 10:38
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 430d, last: 413d
similar bugs (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in __fdget_pos 1 1706d 1706d 0/24 closed as invalid on 2018/03/27 11:08
android-44 INFO: task hung in __fdget_pos 2 1526d 1539d 0/2 auto-closed as invalid on 2019/03/21 05:21
android-49 INFO: task hung in __fdget_pos 22 1527d 1658d 0/3 auto-closed as invalid on 2019/03/20 03:41
android-414 INFO: task hung in __fdget_pos 1 1395d 1326d 0/1 auto-closed as invalid on 2019/07/30 11:39
upstream INFO: task hung in __fdget_pos (2) 36 1418d 1643d 0/24 closed as dup on 2018/10/27 13:29
upstream INFO: task can't die in __fdget_pos 1 288d 288d 0/24 auto-closed as invalid on 2022/04/12 09:48

Sample crash report:
INFO: task syz-executor.0:32378 blocked for more than 143 seconds.
      Not tainted 5.15.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:27792 pid:32378 ppid: 20170 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4940 [inline]
 __schedule+0xc8d/0x1270 kernel/sched/core.c:6287
 schedule+0x14b/0x210 kernel/sched/core.c:6366
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
 __mutex_lock_common+0xdff/0x2550 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743
 __fdget_pos+0x24e/0x2f0 fs/file.c:990
 fdget_pos include/linux/file.h:75 [inline]
 __do_sys_getdents64 fs/readdir.c:365 [inline]
 __se_sys_getdents64+0x1bb/0x4e0 fs/readdir.c:354
 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: 0033:0x7fe056c7c8d9
RSP: 002b:00007fe0541d2188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fe056d81020 RCX: 00007fe056c7c8d9
RDX: 0000000000000034 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007fe056cd6cb4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdbbd10ecf R14: 00007fe0541d2300 R15: 0000000000022000
INFO: task syz-executor.5:32396 blocked for more than 144 seconds.
      Not tainted 5.15.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.5  state:D stack:27792 pid:32396 ppid:   676 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4940 [inline]
 __schedule+0xc8d/0x1270 kernel/sched/core.c:6287
 schedule+0x14b/0x210 kernel/sched/core.c:6366
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
 __mutex_lock_common+0xdff/0x2550 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743
 __fdget_pos+0x24e/0x2f0 fs/file.c:990
 fdget_pos include/linux/file.h:75 [inline]
 __do_sys_getdents64 fs/readdir.c:365 [inline]
 __se_sys_getdents64+0x1bb/0x4e0 fs/readdir.c:354
 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: 0033:0x7f53285d08d9
RSP: 002b:00007f5325b26188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f53286d5020 RCX: 00007f53285d08d9
RDX: 0000000000000034 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f532862acb4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff5597509f R14: 00007f5325b26300 R15: 0000000000022000
INFO: task syz-executor.4:32750 blocked for more than 145 seconds.
      Not tainted 5.15.0-rc4-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.4  state:D stack:27792 pid:32750 ppid:  6437 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4940 [inline]
 __schedule+0xc8d/0x1270 kernel/sched/core.c:6287
 schedule+0x14b/0x210 kernel/sched/core.c:6366
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6425
 __mutex_lock_common+0xdff/0x2550 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:743
 __fdget_pos+0x24e/0x2f0 fs/file.c:990
 fdget_pos include/linux/file.h:75 [inline]
 __do_sys_getdents64 fs/readdir.c:365 [inline]
 __se_sys_getdents64+0x1bb/0x4e0 fs/readdir.c:354
 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: 0033:0x7f8f0301f8d9
RSP: 002b:00007f8f00575188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f8f03124020 RCX: 00007f8f0301f8d9
RDX: 0000000000000034 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f8f03079cb4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe8407a03f R14: 00007f8f00575300 R15: 0000000000022000

Showing all locks held in the system:
4 locks held by kworker/u4:0/8:
1 lock held by khungtaskd/26:
 #0: ffffffff8c91c1c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
1 lock held by in:imklog/6217:
 #0: ffff8880205af270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by agetty/6240:
 #0: ffff8880129c0098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc9000112c2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6c5/0x1c60 drivers/tty/n_tty.c:2113
3 locks held by kworker/0:5/28858:
 #0: ffff8880b9c31558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:474 [inline]
 #0: ffff8880b9c31558 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1317 [inline]
 #0: ffff8880b9c31558 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1620 [inline]
 #0: ffff8880b9c31558 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x188/0x1270 kernel/sched/core.c:6201
 #1: ffff8880b9c1f888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4c1/0x780 kernel/sched/psi.c:880
 #2: ffffffff8c91c1c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:266
2 locks held by syz-executor.0/32374:
1 lock held by syz-executor.0/32378:
 #0: ffff888053d1cd70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by syz-executor.5/32390:
1 lock held by syz-executor.5/32396:
 #0: ffff88801fe454f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by syz-executor.4/32710:
1 lock held by syz-executor.4/32750:
 #0: ffff88805cf73770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by syz-executor.3/805:
1 lock held by syz-executor.3/817:
 #0: ffff88806c7f74f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by syz-executor.2/837:
1 lock held by syz-executor.2/866:
 #0: ffff88807bfe3770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990
2 locks held by syz-executor.1/1023:
1 lock held by syz-executor.1/1028:
 #0: ffff8880592adc70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x2f0 fs/file.c:990

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 26 Comm: khungtaskd Not tainted 5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __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:105
 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
 watchdog+0xc54/0xca0 kernel/hung_task.c:295
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14 Comm: rcu_preempt Not tainted 5.15.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:lookup_object lib/debugobjects.c:198 [inline]
RIP: 0010:__debug_object_init+0x12b/0x1860 lib/debugobjects.c:571
Code: 45 31 f6 eb 10 66 2e 0f 1f 84 00 00 00 00 00 41 ff c6 48 8b 1b 48 85 db 74 3b 4c 8d 7b 18 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 <74> 08 4c 89 ff e8 6b 44 b8 fd 4d 39 27 0f 84 9b 01 00 00 48 89 d8
RSP: 0018:ffffc90000d37a60 EFLAGS: 00000046
RAX: 1ffff1100953b6ce RBX: ffff88804a9db658 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: 0000000000000004 RDI: ffffc90000d37940
RBP: ffffc90000d37c30 R08: dffffc0000000000 R09: 0000000000000003
R10: fffff520001a6f29 R11: 0000000000000004 R12: ffffc90000d37c60
R13: dffffc0000000000 R14: 0000000000000005 R15: ffff88804a9db670
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0049bd0b0 CR3: 000000000c68e000 CR4: 00000000003506f0
DR0: 0000000000000005 DR1: 00000000000000ff DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 init_timer_on_stack_key kernel/time/timer.c:752 [inline]
 schedule_timeout+0x11d/0x300 kernel/time/timer.c:1879
 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1957
 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2130
 kthread+0x453/0x480 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30
----------------
Code disassembly (best guess):
   0:	45 31 f6             	xor    %r14d,%r14d
   3:	eb 10                	jmp    0x15
   5:	66 2e 0f 1f 84 00 00 	nopw   %cs:0x0(%rax,%rax,1)
   c:	00 00 00
   f:	41 ff c6             	inc    %r14d
  12:	48 8b 1b             	mov    (%rbx),%rbx
  15:	48 85 db             	test   %rbx,%rbx
  18:	74 3b                	je     0x55
  1a:	4c 8d 7b 18          	lea    0x18(%rbx),%r15
  1e:	4c 89 f8             	mov    %r15,%rax
  21:	48 c1 e8 03          	shr    $0x3,%rax
  25:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
* 2a:	74 08                	je     0x34 <-- trapping instruction
  2c:	4c 89 ff             	mov    %r15,%rdi
  2f:	e8 6b 44 b8 fd       	callq  0xfdb8449f
  34:	4d 39 27             	cmp    %r12,(%r15)
  37:	0f 84 9b 01 00 00    	je     0x1d8
  3d:	48 89 d8             	mov    %rbx,%rax

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2021/10/09 10:38 upstream 5d6ab0bb408f efe0f24d .config log report info INFO: task hung in __fdget_pos
ci-upstream-kasan-gce-selinux-root 2021/09/24 19:39 upstream 4c4f0c2bf341 8cac236e .config log report info INFO: task hung in __fdget_pos
ci-upstream-kasan-gce-smack-root 2021/09/22 01:57 upstream 92477dd1faa6 169724fe .config log report info INFO: task hung in __fdget_pos
* Struck through repros no longer work on HEAD.