INFO: task hung in filename_create (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b172b44fcb17 Linux 4.19.206
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1505dbcd300000
kernel config: https://syzkaller.appspot.com/x/.config?x=b9ba3521ce0be3cd
dashboard link: https://syzkaller.appspot.com/bug?extid=b9f6c3c955c68db5f555
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+b9f6c3...@syzkaller.appspotmail.com

kvm: vcpu 0: requested 128 ns lapic timer period limited to 200000 ns
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.2:12947 blocked for more than 140 seconds.
Not tainted 4.19.206-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D29432 12947 13776 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_nested+0x51/0x90 kernel/locking/rwsem.c:194
inode_lock_nested include/linux/fs.h:783 [inline]
filename_create+0x15a/0x490 fs/namei.c:3638
user_path_create fs/namei.c:3696 [inline]
do_symlinkat+0xe1/0x2c0 fs/namei.c:4149
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4665f9
Code: Bad RIP value.
RSP: 002b:00007faf7e1c8188 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 000000000056c0f0 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 00000000200001c0
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c0f0
R13: 00007ffd308e5c3f R14: 00007faf7e1c8300 R15: 0000000000022000

Showing all locks held in the system:
1 lock held by khungtaskd/1570:
#0: 00000000ec58ce52 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441
1 lock held by in:imklog/7813:
#0: 00000000461a1c2f (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
2 locks held by agetty/7848:
#0: 000000009b456af9 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: 000000002b506c1f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1950 drivers/tty/n_tty.c:2154
1 lock held by syz-executor.2/12843:
#0: 00000000a72fbd0d (&sb->s_type->i_mutex_key#35){++++}, at: inode_lock_shared include/linux/fs.h:758 [inline]
#0: 00000000a72fbd0d (&sb->s_type->i_mutex_key#35){++++}, at: lookup_slow fs/namei.c:1688 [inline]
#0: 00000000a72fbd0d (&sb->s_type->i_mutex_key#35){++++}, at: walk_component+0x798/0xda0 fs/namei.c:1811
2 locks held by syz-executor.2/12947:
#0: 0000000050621267 (sb_writers#26){.+.+}, at: sb_start_write include/linux/fs.h:1579 [inline]
#0: 0000000050621267 (sb_writers#26){.+.+}, at: mnt_want_write+0x3a/0xb0 fs/namespace.c:360
#1: 00000000a72fbd0d (&sb->s_type->i_mutex_key#35/1){+.+.}, at: inode_lock_nested include/linux/fs.h:783 [inline]
#1: 00000000a72fbd0d (&sb->s_type->i_mutex_key#35/1){+.+.}, at: filename_create+0x15a/0x490 fs/namei.c:3638

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

NMI backtrace for cpu 1
CPU: 1 PID: 1570 Comm: khungtaskd Not tainted 4.19.206-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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10502 Comm: kworker/u4:6 Not tainted 4.19.206-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_purge_orig
RIP: 0010:hlock_class kernel/locking/lockdep.c:152 [inline]
RIP: 0010:mark_lock+0x66/0x1160 kernel/locking/lockdep.c:3106
Code: c0 74 08 3c 01 0f 8e f1 07 00 00 0f b7 45 20 66 a9 ff 1f 74 7c 48 ba 00 00 00 00 00 fc ff df 4c 89 f1 48 c1 e9 03 0f b6 14 11 <84> d2 74 09 80 fa 03 0f 8e d2 07 00 00 25 ff 1f 00 00 48 69 d8 50
RSP: 0018:ffff88802e39fb60 EFLAGS: 00000802
RAX: 000000000000062e RBX: 0000000000000001 RCX: 1ffff1100954451a
RDX: 0000000000000000 RSI: ffff88804aa228b0 RDI: ffff88804aa22000
RBP: ffff88804aa228b0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000040
R13: ffff88804aa22000 R14: ffff88804aa228d0 R15: 0000000000000006
FS: 0000000000000000(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1d4ff1000 CR3: 00000000a0824000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
mark_held_locks+0xa6/0xf0 kernel/locking/lockdep.c:2810
__trace_hardirqs_on_caller kernel/locking/lockdep.c:2839 [inline]
lockdep_hardirqs_on+0x3a8/0x5c0 kernel/locking/lockdep.c:2884
__local_bh_enable_ip+0x159/0x270 kernel/softirq.c:194
spin_unlock_bh include/linux/spinlock.h:374 [inline]
batadv_purge_orig_ref+0xa2c/0x1110 net/batman-adv/originator.c:1379
batadv_purge_orig+0x17/0x60 net/batman-adv/originator.c:1392
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
----------------
Code disassembly (best guess):
0: c0 74 08 3c 01 shlb $0x1,0x3c(%rax,%rcx,1)
5: 0f 8e f1 07 00 00 jle 0x7fc
b: 0f b7 45 20 movzwl 0x20(%rbp),%eax
f: 66 a9 ff 1f test $0x1fff,%ax
13: 74 7c je 0x91
15: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
1c: fc ff df
1f: 4c 89 f1 mov %r14,%rcx
22: 48 c1 e9 03 shr $0x3,%rcx
26: 0f b6 14 11 movzbl (%rcx,%rdx,1),%edx
* 2a: 84 d2 test %dl,%dl <-- trapping instruction
2c: 74 09 je 0x37
2e: 80 fa 03 cmp $0x3,%dl
31: 0f 8e d2 07 00 00 jle 0x809
37: 25 ff 1f 00 00 and $0x1fff,%eax
3c: 48 rex.W
3d: 69 .byte 0x69
3e: d8 .byte 0xd8
3f: 50 push %rax


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[syzbot]

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