syzbot

INFO: task syz.0.42:6230 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.42        state:D stack:22312 pid:6230  tgid:6229  ppid:5930   task_flags:0x440140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x14fb/0x52c0 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7004
 schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75
 ___down_common kernel/locking/semaphore.c:268 [inline]
 __down_common+0x321/0x730 kernel/locking/semaphore.c:293
 down+0x80/0xd0 kernel/locking/semaphore.c:100
 xfs_buf_lock+0x14d/0x520 fs/xfs/xfs_buf.c:993
 xfs_buf_item_unpin+0x1c4/0x770 fs/xfs/xfs_buf_item.c:551
 xlog_cil_ail_insert fs/xfs/xfs_log_cil.c:-1 [inline]
 xlog_cil_committed+0x9f4/0x1170 fs/xfs/xfs_log_cil.c:995
 xlog_cil_process_committed+0x15c/0x1b0 fs/xfs/xfs_log_cil.c:1025
 xlog_state_shutdown_callbacks+0x277/0x380 fs/xfs/xfs_log.c:438
 xlog_force_shutdown+0x332/0x400 fs/xfs/xfs_log.c:3406
 xfs_do_force_shutdown+0x2ab/0x700 fs/xfs/xfs_fsops.c:507
 xfs_trans_read_buf_map+0x518/0x950 fs/xfs/xfs_trans_buf.c:311
 xfs_trans_read_buf fs/xfs/xfs_trans.h:212 [inline]
 xfs_btree_read_buf_block+0x2b0/0x490 fs/xfs/libxfs/xfs_btree.c:1402
 xfs_btree_lookup_get_block+0x297/0x510 fs/xfs/libxfs/xfs_btree.c:1907
 xfs_btree_lookup+0x45a/0x1350 fs/xfs/libxfs/xfs_btree.c:2018
 xfs_alloc_lookup fs/xfs/libxfs/xfs_alloc.c:166 [inline]
 xfs_alloc_lookup_le fs/xfs/libxfs/xfs_alloc.c:212 [inline]
 xfs_free_ag_extent+0x277/0x17d0 fs/xfs/libxfs/xfs_alloc.c:2080
 __xfs_free_extent+0x36e/0x4f0 fs/xfs/libxfs/xfs_alloc.c:4047
 xfs_extent_free_finish_item+0x292/0x640 fs/xfs/xfs_extfree_item.c:553
 xfs_defer_finish_one+0x5d7/0xd80 fs/xfs/libxfs/xfs_defer.c:595
 xfs_defer_finish_noroll+0x940/0x13b0 fs/xfs/libxfs/xfs_defer.c:707
 xfs_defer_finish+0x1c/0x180 fs/xfs/libxfs/xfs_defer.c:741
 xfs_bunmapi_range+0xc4/0x140 fs/xfs/libxfs/xfs_bmap.c:6169
 xfs_itruncate_extents_flags+0x2f9/0xa10 fs/xfs/xfs_inode.c:1077
 xfs_itruncate_extents fs/xfs/xfs_inode.h:604 [inline]
 xfs_setattr_size+0x980/0xf30 fs/xfs/xfs_iops.c:1095
 xfs_vn_setattr+0x261/0x310 fs/xfs/xfs_iops.c:1171
 notify_change+0xc18/0xf60 fs/attr.c:556
 do_truncate+0x1c2/0x250 fs/open.c:68
 handle_truncate fs/namei.c:4279 [inline]
 do_open fs/namei.c:4675 [inline]
 path_openat+0x2fc4/0x38a0 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6e9a90c799
RSP: 002b:00007f6e99f66028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f6e9ab85fa0 RCX: 00007f6e9a90c799
RDX: 0000000000183341 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f6e9a9a2bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e9ab86038 R14: 00007f6e9ab85fa0 R15: 00007ffc54605238
 </TASK>
INFO: task syz.0.42:6239 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.42        state:D stack:26504 pid:6239  tgid:6229  ppid:5930   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x14fb/0x52c0 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7004
 xlog_wait fs/xfs/xfs_log_priv.h:604 [inline]
 xlog_wait_on_iclog+0x487/0x710 fs/xfs/xfs_log.c:791
 xlog_force_lsn+0x511/0x9b0 fs/xfs/xfs_log.c:2949
 __xfs_trans_commit+0x7d3/0xc20 fs/xfs/xfs_trans.c:877
 xfs_trans_commit+0x13e/0x1c0 fs/xfs/xfs_trans.c:926
 xfs_sync_sb_buf+0x13f/0x230 fs/xfs/libxfs/xfs_sb.c:1490
 xfs_ioc_setlabel+0x1de/0x340 fs/xfs/xfs_ioctl.c:1041
 xfs_file_ioctl+0x9c5/0x1710 fs/xfs/xfs_ioctl.c:1198
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6e9a90c799
RSP: 002b:00007f6e99f45028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6e9ab86090 RCX: 00007f6e9a90c799
RDX: 0000200000000180 RSI: 0000000041009432 RDI: 0000000000000004
RBP: 00007f6e9a9a2bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e9ab86128 R14: 00007f6e9ab86090 R15: 00007ffc54605238
 </TASK>

Showing all locks held in the system:
4 locks held by pr/legacy/17:
1 lock held by khungtaskd/37:
 #0: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:8/985:
2 locks held by getty/5555:
 #0: ffff88802649c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
5 locks held by syz.0.42/6230:
 #0: ffff88802d650480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:493
 #1: ffff88804505bf10 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline]
 #1: ffff88804505bf10 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63
 #2: ffff88804505c0e0 (mapping.invalidate_lock#3){+.+.}-{4:4}, at: xfs_ilock+0x16d/0x3b0 fs/xfs/xfs_inode.c:157
 #3: ffff88802d650770 (sb_internal#2){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x9b0 fs/xfs/xfs_trans.c:254
 #4: ffff88804505bc88 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_setattr_size+0x7f1/0xf30 fs/xfs/xfs_iops.c:1059
1 lock held by syz.0.42/6239:
 #0: ffff88802d650480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:537
5 locks held by syz.1.158/7436:
 #0: ffff888023c94480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:493
 #1: ffff888059d7c790 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline]
 #1: ffff888059d7c790 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63
 #2: ffff888059d7c960 (mapping.invalidate_lock#3){+.+.}-{4:4}, at: xfs_ilock+0x16d/0x3b0 fs/xfs/xfs_inode.c:157
 #3: ffff888023c94770 (sb_internal#2){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x9b0 fs/xfs/xfs_trans.c:254
 #4: ffff888059d7c508 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_setattr_size+0x7f1/0xf30 fs/xfs/xfs_iops.c:1059
1 lock held by syz.1.158/7447:
 #0: ffff888023c94480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:537
2 locks held by kworker/u8:2/7663:
 #0: ffff888029373938 ((wq_completion)xfs-cil/loop2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888029373938 ((wq_completion)xfs-cil/loop2){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc9000ee97c40 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc9000ee97c40 ((work_completion)(&ctx->push_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
1 lock held by syz.2.184/7735:
 #0: ffff88802a002480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:537
1 lock held by udevd/7740:
5 locks held by syz.3.196/7871:
 #0: ffff8880246a4480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:493
 #1: ffff888045111d10 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1033 [inline]
 #1: ffff888045111d10 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63
 #2: ffff888045111ee0 (mapping.invalidate_lock#3){+.+.}-{4:4}, at: xfs_ilock+0x16d/0x3b0 fs/xfs/xfs_inode.c:157
 #3: ffff8880246a4770 (sb_internal#2){.+.+}-{0:0}, at: xfs_trans_alloc+0xd7/0x9b0 fs/xfs/xfs_trans.c:254
 #4: ffff888045111a88 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_setattr_size+0x7f1/0xf30 fs/xfs/xfs_iops.c:1059

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 17 Comm: pr/legacy Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400
Code: e8 8e 16 95 fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 bf 24 fb fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 4a 86 f6 05 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001679d0 EFLAGS: 00000202
RAX: 1ffffffff3329e00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff9994f730 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff852f3c50 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9994f4a0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888126440000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc3b7002000 CR3: 000000003a0e6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:128 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
 wait_for_lsr+0x1aa/0x2f0 drivers/tty/serial/8250/8250_port.c:1961
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
 serial8250_console_write+0x120d/0x1b90 drivers/tty/serial/8250/8250_port.c:3342
 console_emit_next_record kernel/printk/printk.c:3163 [inline]
 console_flush_one_record+0x68b/0xb90 kernel/printk/printk.c:3269
 legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>