syzbot


INFO: task hung in vfs_unlink

Status: auto-closed as invalid on 2020/12/15 00:37
Reported-by: syzbot+9874d7513e8cb5f92cc3@syzkaller.appspotmail.com
First crash: 923d, last: 681d
similar bugs (5):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 INFO: task hung in vfs_unlink (2) 1 436d 436d 0/1 auto-closed as invalid on 2021/08/17 05:41
linux-4.19 INFO: task hung in vfs_unlink (2) 2 690d 752d 0/1 auto-closed as invalid on 2020/12/05 18:54
upstream INFO: task hung in vfs_unlink 32 703d 980d 0/22 auto-closed as invalid on 2020/11/23 01:14
linux-4.19 INFO: task hung in vfs_unlink 6 881d 1006d 0/1 auto-closed as invalid on 2020/05/28 17:30
linux-4.19 INFO: task hung in vfs_unlink (3) 1 329d 329d 0/1 auto-closed as invalid on 2021/12/01 23:35

Sample crash report:
NOHZ: local_softirq_pending 08
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
NOHZ: local_softirq_pending 08
INFO: task syz-executor.0:6365 blocked for more than 140 seconds.
      Not tainted 4.14.193-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D25848  6365      1 0x10000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline]
 rwsem_down_write_failed+0x343/0x6d0 kernel/locking/rwsem-xadd.c:617
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
 __down_write arch/x86/include/asm/rwsem.h:126 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:56
 inode_lock include/linux/fs.h:719 [inline]
 vfs_unlink+0xc0/0x470 fs/namei.c:4018
 do_unlinkat+0x30c/0x5c0 fs/namei.c:4092
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45cf87
RSP: 002b:00007ffe2b049f68 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045cf87
RDX: 00007ffe2b049f80 RSI: 00007ffe2b049f80 RDI: 00007ffe2b04a010
RBP: 000000000000066e R08: 0000000000000000 R09: 0000000000000020
R10: 000000000000001a R11: 0000000000000246 R12: 00007ffe2b04b0a0
R13: 000000000170fa60 R14: 0000000000000000 R15: 00007ffe2b04b0a0

Showing all locks held in the system:
2 locks held by kworker/0:1/24:
 #0:  ("events"){+.+.}, at: [<ffffffff813ba640>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  ((&rew.rew_work)){+.+.}, at: [<ffffffff813ba676>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091
1 lock held by khungtaskd/1064:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff814778d4>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
2 locks held by agetty/6067:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8343ce32>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83432183>] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156
2 locks held by agetty/6069:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8343ce32>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83432183>] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156
3 locks held by syz-executor.0/6365:
 #0:  (sb_writers#3){.+.+}, at: [<ffffffff819441aa>] sb_start_write include/linux/fs.h:1549 [inline]
 #0:  (sb_writers#3){.+.+}, at: [<ffffffff819441aa>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386
 #1:  (&type->i_mutex_dir_key#3/1){+.+.}, at: [<ffffffff8190c481>] inode_lock_nested include/linux/fs.h:754 [inline]
 #1:  (&type->i_mutex_dir_key#3/1){+.+.}, at: [<ffffffff8190c481>] do_unlinkat+0x201/0x5c0 fs/namei.c:4078
 #2:  (&sb->s_type->i_mutex_key#9){++++}, at: [<ffffffff818fdc70>] inode_lock include/linux/fs.h:719 [inline]
 #2:  (&sb->s_type->i_mutex_key#9){++++}, at: [<ffffffff818fdc70>] vfs_unlink+0xc0/0x470 fs/namei.c:4018
3 locks held by kworker/0:5/19017:
 #0:  ("events"){+.+.}, at: [<ffffffff813ba640>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  (key_gc_work){+.+.}, at: [<ffffffff813ba676>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091
 #2:  (rcu_preempt_state.exp_mutex){+.+.}, at: [<ffffffff814d2822>] exp_funnel_lock kernel/rcu/tree_exp.h:272 [inline]
 #2:  (rcu_preempt_state.exp_mutex){+.+.}, at: [<ffffffff814d2822>] _synchronize_rcu_expedited+0x2c2/0x770 kernel/rcu/tree_exp.h:596
3 locks held by syz-executor.0/26484:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff8193b2cb>] __fdget_pos+0x1fb/0x2b0 fs/file.c:769
 #1:  (sb_writers#3){.+.+}, at: [<ffffffff818d4d58>] file_start_write include/linux/fs.h:2708 [inline]
 #1:  (sb_writers#3){.+.+}, at: [<ffffffff818d4d58>] vfs_write+0x3d8/0x4d0 fs/read_write.c:543
 #2:  (&sb->s_type->i_mutex_key#9){++++}, at: [<ffffffff81be545c>] inode_trylock include/linux/fs.h:739 [inline]
 #2:  (&sb->s_type->i_mutex_key#9){++++}, at: [<ffffffff81be545c>] ext4_file_write_iter+0x1cc/0xd20 fs/ext4/file.c:236

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

NMI backtrace for cpu 1
CPU: 1 PID: 1064 Comm: khungtaskd Not tainted 4.14.193-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5b9/0xb40 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7834 Comm: kworker/u4:7 Not tainted 4.14.193-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
task: ffff888082bee480 task.stack: ffff88804dad8000
RIP: 0010:__lock_release kernel/locking/lockdep.c:3804 [inline]
RIP: 0010:lock_release+0x384/0x870 kernel/locking/lockdep.c:4017
RSP: 0018:ffff88804dadfc48 EFLAGS: 00000802
RAX: dffffc0000000000 RBX: 1ffff11009b5bf8c RCX: 1ffff1101057ddab
RDX: 1ffffffff14b4980 RSI: 0000000000000003 RDI: ffff888082bee480
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff888082bee480 R12: ae2069098852e06b
R13: 0000000000000000 R14: ffff888082bee480 R15: 0000000000000003
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0ca78ae010 CR3: 000000008bcca000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rcu_lock_release include/linux/rcupdate.h:247 [inline]
 rcu_read_unlock include/linux/rcupdate.h:685 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:420 [inline]
 batadv_nc_worker+0x5a7/0xc50 net/batman-adv/network-coding.c:726
 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 78 08 00 00 8d 55 01 44 89 fe 4c 89 f7 e8 f5 ea ff ff 85 c0 75 38 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 41 83 e5 07 48 c1 ea 03 <41> 83 c5 03 0f b6 04 02 41 38 c5 7c 08 84 c0 0f 85 b8 02 00 00 

Crashes (8):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2020/08/17 00:36 linux-4.14.y 14b58326976d 5ce13532 .config log report
ci2-linux-4-14 2020/05/14 06:30 linux-4.14.y ab9dfda23248 a885920d .config log report
ci2-linux-4-14 2020/02/29 08:25 linux-4.14.y 78d697fc93f9 c88c7b75 .config log report
ci2-linux-4-14 2020/02/17 21:00 linux-4.14.y 98db2bf27b9e 72bfa6f2 .config log report
ci2-linux-4-14 2020/01/13 13:33 linux-4.14.y 6d0c334a400d 99565c1a .config log report
ci2-linux-4-14 2020/01/10 10:47 linux-4.14.y b0cdffaa546e 4de4e9f0 .config log report
ci2-linux-4-14 2020/01/03 06:05 linux-4.14.y 4c5bf01e16a7 25a0186e .config log report
ci2-linux-4-14 2019/12/19 08:50 linux-4.14.y bfb9e5c03076 79b211f7 .config log report