syzbot

INFO: task syz-executor409:4272 blocked for more than 143 seconds.
      Not tainted 6.1.141-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor409 state:D stack:24352 pid:4272  ppid:4271   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10e9/0x40d0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 wb_wait_for_completion+0x162/0x280 fs/fs-writeback.c:191
 __writeback_inodes_sb_nr+0x1f3/0x240 fs/fs-writeback.c:2653
 sync_filesystem+0x9f/0x220 fs/sync.c:54
 generic_shutdown_super+0x6b/0x340 fs/super.c:474
 kill_block_super+0x7c/0xe0 fs/super.c:1470
 deactivate_locked_super+0x93/0xf0 fs/super.c:332
 cleanup_mnt+0x463/0x4f0 fs/namespace.c:1182
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc0fa02e487
RSP: 002b:00007ffe0749c738 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 000000000001ff50 RCX: 00007fc0fa02e487
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe0749c7f0
RBP: 00007ffe0749c7f0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000202 R12: 00007ffe0749d860
R13: 00005555606ab6c0 R14: 431bde82d7b634db R15: 00007ffe0749d880
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8c92b430 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8c92bc50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8c92aaa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by kworker/u4:4/69:
2 locks held by getty/4016:
 #0: ffff88803086f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000326b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
1 lock held by syz-executor409/4272:
 #0: ffff88801ff380e0 (&type->s_umount_key#42){+.+.}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 69 Comm: kworker/u4:4 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:122 [inline]
RIP: 0010:lock_is_held_type+0x3d/0x190 kernel/locking/lockdep.c:5698
Code: 28 00 00 00 48 89 44 24 08 bd ff ff ff ff 83 3d bc 26 ef 03 00 0f 84 03 01 00 00 65 8b 05 cb e5 f2 75 85 c0 0f 85 f4 00 00 00 <65> 48 8b 1d 7b db f2 75 83 bb dc 0a 00 00 00 0f 85 df 00 00 00 41
RSP: 0018:ffffc900015a71e0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffea0001ce1dc0 RCX: 9b74345e5d3a5f00
RDX: ffff8880187a0000 RSI: 00000000ffffffff RDI: ffffffff8c92aaa0
RBP: 00000000ffffffff R08: dffffc0000000000 R09: fffff9400039c3bf
R10: fffff9400039c3bf R11: 1ffffd400039c3be R12: ffff88801790bf18
R13: 1ffff920002b4e58 R14: ffff888017834b00 R15: ffffc900015a72c0
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055dddfb8c168 CR3: 000000007ee57000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 xa_entry include/linux/xarray.h:1198 [inline]
 xas_reload+0x19c/0x470 include/linux/xarray.h:1583
 mapping_get_entry mm/filemap.c:1894 [inline]
 __filemap_get_folio+0x2a4/0xdd0 mm/filemap.c:1943
 pagecache_get_page+0x26/0x250 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:646 [inline]
 grow_dev_page fs/buffer.c:946 [inline]
 grow_buffers fs/buffer.c:1011 [inline]
 __getblk_slow fs/buffer.c:1038 [inline]
 __getblk_gfp+0x2d8/0xb20 fs/buffer.c:1333
 udf_update_inode+0xf1/0x2ac0 fs/udf/inode.c:1588
 write_inode fs/fs-writeback.c:1460 [inline]
 __writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1677
 writeback_sb_inodes+0xad8/0x17d0 fs/fs-writeback.c:1903
 wb_writeback+0x468/0xd00 fs/fs-writeback.c:2077
 wb_do_writeback fs/fs-writeback.c:2220 [inline]
 wb_workfn+0x435/0xec0 fs/fs-writeback.c:2260
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.286 msecs