INFO: task hung in __writeback_inodes_sb_nr (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 41f36d7859a7 Linux 4.14.296
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12a7ea12880000
kernel config: https://syzkaller.appspot.com/x/.config?x=20cc5ea0fe276fa6
dashboard link: https://syzkaller.appspot.com/bug?extid=5c28d141082d2c22172f
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/941b591cedec/disk-41f36d78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2eea2720f8fc/vmlinux-41f36d78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c3ce0be6b9a/bzImage-41f36d78.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c28d1...@syzkaller.appspotmail.com

Bluetooth: hci1 command 0x0406 tx timeout
Bluetooth: hci0 command 0x0406 tx timeout
Bluetooth: hci4 command 0x0406 tx timeout
Bluetooth: hci3 command 0x0406 tx timeout
Bluetooth: hci5 command 0x0406 tx timeout
INFO: task syz-executor.2:7975 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.2 D25840 7975 1 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
wb_wait_for_completion fs/fs-writeback.c:222 [inline]
wb_wait_for_completion+0x118/0x170 fs/fs-writeback.c:218
__writeback_inodes_sb_nr+0x164/0x1d0 fs/fs-writeback.c:2343
__sync_filesystem fs/sync.c:36 [inline]
sync_filesystem fs/sync.c:64 [inline]
sync_filesystem+0x8c/0x230 fs/sync.c:48
generic_shutdown_super+0x70/0x370 fs/super.c:432
kill_block_super+0x95/0xe0 fs/super.c:1161
deactivate_locked_super+0x6c/0xd0 fs/super.c:319
deactivate_super+0x7f/0xa0 fs/super.c:350
cleanup_mnt+0x186/0x2c0 fs/namespace.c:1183
task_work_run+0x11f/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f664107fa17
RSP: 002b:00007ffdd8d75358 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f664107fa17
RDX: 00007ffdd8d7542a RSI: 000000000000000a RDI: 00007ffdd8d75420
RBP: 00007ffdd8d75420 R08: 00000000ffffffff R09: 00007ffdd8d751f0
R10: 0000555556daf903 R11: 0000000000000246 R12: 00007f66410d8826
R13: 00007ffdd8d764e0 R14: 0000555556daf810 R15: 00007ffdd8d76520
INFO: task syz-executor.3:10593 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D30144 10593 7978 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f39a8a615a9
RSP: 002b:00007f39a6fb3168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f39a8b82050 RCX: 00007f39a8a615a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f39a8abc7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe4ebb7eaf R14: 00007f39a6fb3300 R15: 0000000000022000
INFO: task syz-executor.3:10597 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D29672 10597 7978 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f39a8a615a9
RSP: 002b:00007f39a6f92168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f39a8b82120 RCX: 00007f39a8a615a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f39a8abc7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe4ebb7eaf R14: 00007f39a6f92300 R15: 0000000000022000
INFO: task syz-executor.0:10621 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D30144 10621 7966 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f63139315a9
RSP: 002b:00007f6311e83168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f6313a52050 RCX: 00007f63139315a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f631398c7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd2f8a9f9f R14: 00007f6311e83300 R15: 0000000000022000
INFO: task syz-executor.0:10623 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D30280 10623 7966 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f63139315a9
RSP: 002b:00007f6311e62168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f6313a52120 RCX: 00007f63139315a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f631398c7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd2f8a9f9f R14: 00007f6311e62300 R15: 0000000000022000
INFO: task syz-executor.1:10636 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1 D28016 10636 7977 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f8df13715a9
RSP: 002b:00007f8def8e4168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f8df1491f80 RCX: 00007f8df13715a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8df13cc7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcffbcb73f R14: 00007f8def8e4300 R15: 0000000000022000
INFO: task syz-executor.1:10641 blocked for more than 140 seconds.
Not tainted 4.14.296-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1 D30120 10641 7977 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2811 [inline]
__schedule+0x88b/0x1de0 kernel/sched/core.c:3387
schedule+0x8d/0x1b0 kernel/sched/core.c:3431
__rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:292 [inline]
rwsem_down_read_failed+0x1e6/0x350 kernel/locking/rwsem-xadd.c:309
call_rwsem_down_read_failed+0x14/0x30 arch/x86/lib/rwsem.S:94
__down_read arch/x86/include/asm/rwsem.h:66 [inline]
down_read+0x44/0x80 kernel/locking/rwsem.c:26
iterate_supers+0xda/0x490 fs/super.c:611
sys_sync+0x78/0x130 fs/sync.c:113
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f8df13715a9
RSP: 002b:00007f8def8c3168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f8df1492050 RCX: 00007f8df13715a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f8df13cc7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcffbcb73f R14: 00007f8def8c3300 R15: 0000000000022000

Showing all locks held in the system:
1 lock held by khungtaskd/1533:
#0: (tasklist_lock){.+.?}, at: [<ffffffff87028579>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by syz-executor.2/7975:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff81877187>] deactivate_super+0x77/0xa0 fs/super.c:349
1 lock held by syz-executor.3/10593:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611
1 lock held by syz-executor.3/10597:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611
1 lock held by syz-executor.0/10621:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611
1 lock held by syz-executor.0/10623:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611
1 lock held by syz-executor.1/10636:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611
1 lock held by syz-executor.1/10641:
#0: (&type->s_umount_key#68){++++}, at: [<ffffffff8187a25a>] iterate_supers+0xda/0x490 fs/super.c:611

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

NMI backtrace for cpu 0
CPU: 0 PID: 1533 Comm: khungtaskd Not tainted 4.14.296-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x13a/0x180 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 9269 Comm: kworker/u4:5 Not tainted 4.14.296-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
task: ffff888059f5c5c0 task.stack: ffff888059f60000
RIP: 0010:unwind_next_frame+0x5b/0x17d0 arch/x86/kernel/unwind_orc.c:325
RSP: 0000:ffff888059f677e8 EFLAGS: 00000a02
RAX: 0000000000000000 RBX: 1ffff1100b3ecf04 RCX: 0000000000000007
RDX: 1ffff1100b3ecf15 RSI: ffff888059f67798 RDI: ffff888059f678a8
RBP: ffff888059f67918 R08: 0000000000000001 R09: 0000000000000001
R10: ffff888059f67cf0 R11: 0000000000000001 R12: ffff888059f67930
R13: 0000000000000000 R14: ffff88813fe74ac0 R15: ffff888059f678a8
FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c874c8608 CR3: 00000000a2e02000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__save_stack_trace+0x90/0x160 arch/x86/kernel/stacktrace.c:44
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
slab_post_alloc_hook mm/slab.h:442 [inline]
slab_alloc_node mm/slab.c:3333 [inline]
kmem_cache_alloc_node_trace+0x13d/0x400 mm/slab.c:3659
__do_kmalloc_node mm/slab.c:3681 [inline]
__kmalloc_node_track_caller+0x38/0x70 mm/slab.c:3696
__kmalloc_reserve net/core/skbuff.c:137 [inline]
pskb_expand_head+0x128/0xd30 net/core/skbuff.c:1472
__skb_cow include/linux/skbuff.h:2974 [inline]
skb_cow_head include/linux/skbuff.h:3008 [inline]
batadv_skb_head_push+0x18b/0x1d0 net/batman-adv/soft-interface.c:78
batadv_send_skb_packet+0xf2/0x5c0 net/batman-adv/send.c:97
batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:569 [inline]
batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:597 [inline]
batadv_iv_send_outstanding_bat_ogm_packet+0x545/0x6f0 net/batman-adv/bat_iv_ogm.c:1849
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: b5 88 48 c1 eb 03 48 c7 44 24 48 80 6f 23 81 48 8d 14 03 c7 02 f1 f1 f1 f1 c7 42 04 00 f3 f3 f3 48 89 fa 48 c1 ea 03 0f b6 04 02 <84> c0 74 08 3c 03 0f 8e 13 09 00 00 41 8b 2f 31 c0 85 ed 75 21


---
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[syzbot]

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