INFO: task hung in vfs_unlink (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 53bd76690e27 Linux 4.19.200
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=123348ba300000
kernel config: https://syzkaller.appspot.com/x/.config?x=64e2049c2212438d
dashboard link: https://syzkaller.appspot.com/bug?extid=2f01da485d36b32891cd
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2f01da...@syzkaller.appspotmail.com

Bluetooth: hci4: command 0x0406 tx timeout
ieee802154 phy0 wpan0: encryption failed: -22
ieee802154 phy1 wpan1: encryption failed: -22
ieee802154 phy0 wpan0: encryption failed: -22
ieee802154 phy1 wpan1: encryption failed: -22
INFO: task syz-executor.4:30443 blocked for more than 140 seconds.
Not tainted 4.19.200-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4 D24120 30443 1 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
__rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline]
rwsem_down_write_failed+0x3aa/0x760 kernel/locking/rwsem-xadd.c:618
call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:117
__down_write arch/x86/include/asm/rwsem.h:142 [inline]
down_write+0x4f/0x90 kernel/locking/rwsem.c:72
inode_lock include/linux/fs.h:748 [inline]
vfs_unlink+0xca/0x4e0 fs/namei.c:3993
do_unlinkat+0x3b8/0x660 fs/namei.c:4065
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x465f27
Code: Bad RIP value.
RSP: 002b:00007ffedd2d3a38 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000465f27
RDX: 00007ffedd2d3a70 RSI: 00007ffedd2d3a70 RDI: 00007ffedd2d3b00
RBP: 00007ffedd2d3b00 R08: 0000000000000001 R09: 00007ffedd2d38d0
R10: 00000000017b98c3 R11: 0000000000000206 R12: 00000000004bee90
R13: 00007ffedd2d4bd0 R14: 00000000017b9810 R15: 00007ffedd2d4c10

Showing all locks held in the system:
1 lock held by khungtaskd/1570:
#0: 000000008dd368fc (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441
1 lock held by in:imklog/7776:
#0: 0000000009741403 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
2 locks held by agetty/7809:
#0: 000000009596ddb5 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 0000000012cf78e7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1950 drivers/tty/n_tty.c:2154
3 locks held by syz-executor.4/30443:
#0: 00000000db16ca72 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline]
#0: 00000000db16ca72 (sb_writers#3){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360
#1: 000000000676aa67 (&type->i_mutex_dir_key#3/1){+.+.}, at: inode_lock_nested include/linux/fs.h:783 [inline]
#1: 000000000676aa67 (&type->i_mutex_dir_key#3/1){+.+.}, at: do_unlinkat+0x27d/0x660 fs/namei.c:4051
#2: 000000007e495a02 (&sb->s_type->i_mutex_key#10){++++}, at: inode_lock include/linux/fs.h:748 [inline]
#2: 000000007e495a02 (&sb->s_type->i_mutex_key#10){++++}, at: vfs_unlink+0xca/0x4e0 fs/namei.c:3993
3 locks held by syz-executor.4/1471:
#0: 00000000ac9395b1 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
#1: 00000000db16ca72 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2779 [inline]
#1: 00000000db16ca72 (sb_writers#3){.+.+}, at: vfs_write+0x463/0x540 fs/read_write.c:548
#2: 000000007e495a02 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:768 [inline]
#2: 000000007e495a02 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x21f/0xf20 fs/ext4/file.c:238

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

NMI backtrace for cpu 0
CPU: 0 PID: 1570 Comm: khungtaskd Not tainted 4.19.200-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x991/0xe60 kernel/hung_task.c:287
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4688 Comm: systemd-journal Not tainted 4.19.200-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:784 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/paravirt.h:806 [inline]
RIP: 0010:lock_acquire+0x97/0x3c0 kernel/locking/lockdep.c:3903
Code: 82 f1 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 eb 02 00 00 48 83 3d f0 30 a6 08 00 0f 84 75 02 00 00 9c <58> 0f 1f 44 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 44 24 08 48
RSP: 0018:ffff8880a0d2fa60 EFLAGS: 00000082
RAX: 1ffffffff13e3050 RBX: ffff8880a0d20480 RCX: 0000000000000002
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8880a0d20d04
RBP: ffff8880a2c5bc48 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000002 R15: 0000000000000001
FS: 00007f467bd918c0(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f46793f9028 CR3: 00000000a0dfc000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.