syzbot

INFO: task kworker/u8:1:12 blocked for more than 143 seconds.
      Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1    state:D stack:21328 pid:12    tgid:12    ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x17fb/0x4be0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6905
 __mutex_lock_common kernel/locking/mutex.c:665 [inline]
 __mutex_lock+0x7e7/0xee0 kernel/locking/mutex.c:735
 exfat_write_inode+0xe5/0x1a0 fs/exfat/inode.c:108
 write_inode fs/fs-writeback.c:1525 [inline]
 __writeback_single_inode+0x708/0x10d0 fs/fs-writeback.c:1745
 writeback_sb_inodes+0x820/0x1360 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2047
 wb_writeback+0x427/0xb80 fs/fs-writeback.c:2158
 wb_check_background_flush fs/fs-writeback.c:2228 [inline]
 wb_do_writeback fs/fs-writeback.c:2316 [inline]
 wb_workfn+0xc4b/0x1080 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u8:1/12:
 #0: ffff8880206f0948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
 #0: ffff8880206f0948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3310
 #1: ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
 #1: ffffc90000117d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310
 #2: ffff88805a26e0e0 (&type->s_umount_key#43){.+.+}-{4:4}, at: super_trylock_shared+0x22/0xf0 fs/super.c:562
 #3: ffff88805a18a0e8 (&sbi->s_lock){+.+.}-{4:4}, at: exfat_write_inode+0xe5/0x1a0 fs/exfat/inode.c:108
1 lock held by khungtaskd/30:
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937aa0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
1 lock held by klogd/5185:
 #0: ffff8880b863e758 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598
2 locks held by getty/5578:
 #0: ffff88814d0da0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002ff62f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
3 locks held by syz-executor257/5839:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xff6/0x1040 kernel/hung_task.c:397
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5839 Comm: syz-executor257 Not tainted 6.13.0-rc1-syzkaller-00025-gfeffde684ac2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:lockdep_hardirqs_off+0x19/0x110 kernel/locking/lockdep.c:4480
Code: 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 <83> 3d 40 7e 50 04 00 0f 84 8e 00 00 00 49 89 fe 65 8b 05 b8 04 3c
RSP: 0018:ffffc90004196d88 EFLAGS: 00000086
RAX: ca45c1d457419e00 RBX: ffffffff822bf8b0 RCX: ffff888034019e00
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff822bf8b0
RBP: ffffc90004196ef0 R08: ffffffff822bf899 R09: 0000000000000000
R10: ffffc90004197320 R11: fffff52000832e68 R12: 0000000000000246
R13: dffffc0000000000 R14: 0000000000000200 R15: 00000000000000a6
FS:  000055556c114380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d3cb86ae98 CR3: 0000000079cd2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 trace_hardirqs_off+0x12/0x40 kernel/trace/trace_preemptirq.c:73
 lookup_bh_lru fs/buffer.c:1359 [inline]
 __find_get_block+0x190/0x1150 fs/buffer.c:1394
 bdev_getblk+0x33/0x550 fs/buffer.c:1425
 __bread_gfp+0x86/0x400 fs/buffer.c:1485
 sb_bread include/linux/buffer_head.h:346 [inline]
 exfat_get_dentry+0x53b/0x730 fs/exfat/dir.c:672
 exfat_find_dir_entry+0x56a/0x29c0 fs/exfat/dir.c:1028
 exfat_find fs/exfat/namei.c:629 [inline]
 exfat_lookup+0x810/0x1e70 fs/exfat/namei.c:727
 lookup_open fs/namei.c:3627 [inline]
 open_last_lookups fs/namei.c:3748 [inline]
 path_openat+0x11a7/0x3590 fs/namei.c:3984
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_open fs/open.c:1425 [inline]
 __se_sys_open fs/open.c:1421 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1421
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f948f247c59
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffea51c2928 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000020000e00 RCX: 00007f948f247c59
RDX: 0000000000000000 RSI: 0000000000064842 RDI: 00000000200005c0
RBP: 00007f948f2bc5f0 R08: 000055556c1154c0 R09: 000055556c1154c0
R10: 000055556c1154c0 R11: 0000000000000246 R12: 00007ffea51c2950
R13: 00007ffea51c2b78 R14: 431bde82d7b634db R15: 00007f948f29003b
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.490 msecs