[v5.15] INFO: task hung in store_rotate_all

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 28c35638ec51 Linux 5.15.219
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14a2ce25580000
kernel config: https://syzkaller.appspot.com/x/.config?x=21845b39f8fc6be8
dashboard link: https://syzkaller.appspot.com/bug?extid=09cead7d00f3e16ac5a2
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/baa03a1911e6/disk-28c35638.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fc932057f792/vmlinux-28c35638.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2d0d901fc7bd/bzImage-28c35638.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09cead...@syzkaller.appspotmail.com

INFO: task syz.5.734:6508 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.734 state:D stack:25456 pid: 6508 ppid: 6287 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11c3/0x4350 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
__down_common+0x289/0x3b0 kernel/locking/semaphore.c:228
down+0x7e/0xd0 kernel/locking/semaphore.c:63
console_lock+0x29/0x70 kernel/printk/printk.c:2557
store_rotate_all+0x28/0x510 drivers/video/fbdev/core/fbcon.c:3195
kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
call_write_iter include/linux/fs.h:2179 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x748/0xd70 fs/read_write.c:594
ksys_write+0x153/0x260 fs/read_write.c:647
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: 0033:0x7f24106bf159
RSP: 002b:00007f240e917028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2410946fa0 RCX: 00007f24106bf159
RDX: 0000000000000002 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007f2410756024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2410947038 R14: 00007f2410946fa0 R15: 00007fffb2e14818
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3949:
#0: ffff88814cbfa098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
2 locks held by kworker/0:4/4259:
#0: ffff888016c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000318fd00 ((work_completion)(&rew.rew_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
3 locks held by kworker/0:5/4263:
#0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc900031bfd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
#2: ffff8880283c0240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x283/0x3380 drivers/net/netdevsim/fib.c:1480
2 locks held by kworker/u4:8/4338:
#0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000323fd00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
3 locks held by kworker/0:6/5326:
3 locks held by kworker/0:7/6159:
#0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc900033ffd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
#2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
#2: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
1 lock held by syz.1.689/6367:
4 locks held by syz.5.734/6508:
#0: ffff88807dbd5770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
#1: ffff88805e268460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
#2: ffff8880604c4088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x500 fs/kernfs/file.c:287
#3: ffff888017bfcda0 (kn->active#508){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288
2 locks held by syz.7.1149/7651:
3 locks held by syz.4.1170/7740:
1 lock held by syz.0.1177/7744:
2 locks held by syz.3.1270/8110:
#0: ffffffff8c9f6428 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8c9f6428 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
#1: ffff88807a9c81c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x6f/0x470 drivers/tty/tty_io.c:1430
1 lock held by syz.6.1275/8133:
#0: ffffffff8c9f6428 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8c9f6428 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
2 locks held by syz.4.1301/8276:
6 locks held by syz-executor/8384:
1 lock held by syz.4.1328/8425:
#0: ffff8880754f20e0 (&type->s_umount_key#91/1){+.+.}-{3:3}, at: alloc_super+0x200/0x970 fs/super.c:229
2 locks held by modprobe/8430:

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

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 07/24/2026
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+0xe1b/0xe60 kernel/hung_task.c:369
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>


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