syzbot

INFO: task syz-executor331:5826 blocked for more than 143 seconds.
      Not tainted 6.12.0-rc6-next-20241108-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor331 state:D stack:23808 pid:5826  tgid:5826  ppid:5823   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6753
 __schedule_loop kernel/sched/core.c:6830 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6845
 bit_wait+0x12/0xd0 kernel/sched/wait_bit.c:237
 __wait_on_bit+0xb0/0x2f0 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0x1d5/0x260 kernel/sched/wait_bit.c:64
 wait_on_bit include/linux/wait_bit.h:77 [inline]
 gfs2_glock_wait+0xc7/0x2b0 fs/gfs2/glock.c:1339
 gfs2_glock_nq_init fs/gfs2/glock.h:238 [inline]
 __gfs2_lookup+0x11b/0x280 fs/gfs2/inode.c:906
 __lookup_slow+0x28c/0x3f0 fs/namei.c:1791
 lookup_slow+0x53/0x70 fs/namei.c:1808
 walk_component+0x2e1/0x410 fs/namei.c:2112
 lookup_last fs/namei.c:2610 [inline]
 path_lookupat+0x16f/0x450 fs/namei.c:2634
 filename_lookup+0x2a3/0x670 fs/namei.c:2663
 user_path_at+0x3a/0x60 fs/namei.c:3070
 ksys_umount fs/namespace.c:2033 [inline]
 __do_sys_umount fs/namespace.c:2041 [inline]
 __se_sys_umount fs/namespace.c:2039 [inline]
 __x64_sys_umount+0xf1/0x170 fs/namespace.c:2039
 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: 0033:0x7fdd3ea75387
RSP: 002b:00007ffc542529e8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdd3ea75387
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc54252aa0
RBP: 00007ffc54252aa0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffc54253b90
R13: 00005555896ca740 R14: 00005555896b9338 R15: 431bde82d7b634db
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e93c560 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e93c560 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e93c560 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6744
2 locks held by getty/5584:
 #0: ffff88814cf920a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000323b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by syz-executor331/5826:
 #0: ffff8880764a07f8 (&type->i_mutex_dir_key#6){.+.+}-{4:4}, at: inode_lock_shared include/linux/fs.h:827 [inline]
 #0: ffff8880764a07f8 (&type->i_mutex_dir_key#6){.+.+}-{4:4}, at: lookup_slow+0x45/0x70 fs/namei.c:1807

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-rc6-next-20241108-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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+0xffb/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: 35 Comm: kworker/u8:2 Not tainted 6.12.0-rc6-next-20241108-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:check_kcov_mode kernel/kcov.c:194 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x37/0x70 kernel/kcov.c:217
Code: c0 d4 03 00 65 8b 15 a0 58 64 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc90000ab77f8 EFLAGS: 00000046
RAX: ffffffff81434d96 RBX: ffff8880b873f358 RCX: ffff88801daa3c00
RDX: 0000000000000000 RSI: ffff88801daa3c80 RDI: 0000000000000001
RBP: 0000000000000001 R08: dffffc0000000000 R09: ffff88801daa3c00
R10: dffffc0000000000 R11: fffffbfff203910f R12: 000000000000018b
R13: ffff88801daa3d78 R14: dffffc0000000000 R15: 1ffff11003b547af
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a4124da600 CR3: 000000000e738000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
 arch_scale_cpu_capacity+0x16/0xb0 arch/x86/kernel/cpu/aperfmperf.c:425
 util_est_update kernel/sched/fair.c:5020 [inline]
 dequeue_task_fair+0x28e/0x550 kernel/sched/fair.c:7195
 block_task kernel/sched/core.c:2131 [inline]
 try_to_block_task kernel/sched/core.c:6590 [inline]
 __schedule+0x5f2/0x4c30 kernel/sched/core.c:6702
 __schedule_loop kernel/sched/core.c:6830 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6845
 toggle_allocation_gate+0x171/0x260 mm/kfence/core.c:851
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 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>