[v5.15] INFO: task hung in __gfs2_glock_dq

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 93741761e5e3 Linux 5.15.207
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17777a73980000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=7ae16f6edd3fc72ec547
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7087b65c18a1/disk-93741761.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5892df79f094/vmlinux-93741761.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4602fe2cead2/bzImage-93741761.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7ae16f...@syzkaller.appspotmail.com

INFO: task syz.0.76:4527 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.76 state:D stack:24464 pid: 4527 ppid: 4191 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
bit_wait+0xd/0xc0 kernel/sched/wait_bit.c:199
__wait_on_bit kernel/sched/wait_bit.c:49 [inline]
out_of_line_wait_on_bit+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_bit include/linux/wait_bit.h:76 [inline]
__gfs2_glock_dq+0x6b5/0xa10 fs/gfs2/glock.c:1588
gfs2_glock_dq fs/gfs2/glock.c:1652 [inline]
gfs2_glock_dq_uninit+0x4f/0x110 fs/gfs2/glock.c:1672
init_per_node+0x12f/0x3e0 fs/gfs2/ops_fstype.c:979
gfs2_fill_super+0x17d1/0x1f00 fs/gfs2/ops_fstype.c:1294
get_tree_bdev+0x3f1/0x610 fs/super.c:1325
gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1332
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fac99f980ca
RSP: 002b:00007fac981efe58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fac981efee0 RCX: 00007fac99f980ca
RDX: 00002000000124c0 RSI: 0000200000000100 RDI: 00007fac981efea0
RBP: 00002000000124c0 R08: 00007fac981efee0 R09: 0000000000800010
R10: 0000000000800010 R11: 0000000000000246 R12: 0000200000000100
R13: 00007fac981efea0 R14: 00000000000125ff R15: 0000200000000180
</TASK>
INFO: task gfs2_quotad:4537 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:gfs2_quotad state:D stack:25968 pid: 4537 ppid: 2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
do_wait_for_common+0x2a2/0x450 kernel/sched/completion.c:85
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
kthread_stop+0x16e/0x540 kernel/kthread.c:666
gfs2_make_fs_ro+0x20a/0x620 fs/gfs2/super.c:543
signal_our_withdraw fs/gfs2/util.c:166 [inline]
gfs2_withdraw+0x610/0x1490 fs/gfs2/util.c:343
gfs2_dinode_in fs/gfs2/glops.c:465 [inline]
gfs2_inode_refresh+0xb64/0xff0 fs/gfs2/glops.c:485
inode_go_lock+0x127/0x470 fs/gfs2/glops.c:510
do_promote+0x741/0xab0 fs/gfs2/glock.c:507
finish_xmote+0x4df/0xb00 fs/gfs2/glock.c:678
do_xmote+0x7b6/0x1120 fs/gfs2/glock.c:824
gfs2_glock_nq+0xc7a/0x1550 fs/gfs2/glock.c:1534
gfs2_glock_nq_init fs/gfs2/glock.h:246 [inline]
do_sync+0x4ab/0xc40 fs/gfs2/quota.c:927
gfs2_quota_sync+0x32c/0x700 fs/gfs2/quota.c:1329
quotad_check_timeo fs/gfs2/quota.c:1519 [inline]
gfs2_quotad+0x403/0x890 fs/gfs2/quota.c:1586
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c31f320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3953:
#0: ffff88802baad098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002d032e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
2 locks held by kworker/u4:6/4243:
1 lock held by syz.0.76/4527:
#0: ffff88807587a0e0 (&type->s_umount_key#64/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
2 locks held by gfs2_quotad/4537:
#0: ffff8880761d0b70 (&sdp->sd_quota_sync_mutex){+.+.}-{3:3}, at: gfs2_quota_sync+0x91/0x700 fs/gfs2/quota.c:1313
#1: ffff888074fb3790 (&gfs2_quota_imutex_key){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#1: ffff888074fb3790 (&gfs2_quota_imutex_key){+.+.}-{3:3}, at: do_sync+0x35a/0xc40 fs/gfs2/quota.c:919
1 lock held by syz.3.472/6091:
#0: ffff88807587a0e0 (&type->s_umount_key#116){.+.+}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:716
1 lock held by sed/8504:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe0f/0xe50 kernel/hung_task.c:369
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4243 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: bat_events batadv_nc_worker
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:331 [inline]
RIP: 0010:rcu_is_watching+0x36/0xa0 kernel/rcu/tree.c:1123
Code: e8 1f f8 57 08 89 c3 83 f8 08 73 5c 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 20 38 e3 8b 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 20 73 59 00 48 c7 c3 08 b3 03 00 49 03 1e 48 89
RSP: 0018:ffffc900031afbc0 EFLAGS: 00000246
RAX: 1ffffffff17c6705 RBX: 0000000000000001 RCX: 27a6aa07d4593500
RDX: 0000000000000000 RSI: ffffffff8a7a06e0 RDI: ffffffff8a7a06a0
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff203ac18
R10: dffffc0000000000 R11: fffffbfff203ac19 R12: 000000000000012b
R13: fffffffffffffe38 R14: ffffffff8be33828 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f60cd9c6440 CR3: 000000000c08e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000071 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rcu_read_unlock include/linux/rcupdate.h:769 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
batadv_nc_worker+0x1dc/0x5c0 net/batman-adv/network-coding.c:723
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>


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