INFO: task syz.6.640:6730 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.640       state:D
 stack:25776 pid: 6730 ppid:  5669 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
 rwsem_down_write_slowpath+0xe63/0x13a0 kernel/locking/rwsem.c:1165
 inode_lock include/linux/fs.h:787 [inline]
 lock_mount+0x60/0x2a0 fs/namespace.c:2260
 do_loopback+0x25c/0x480 fs/namespace.c:2421
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
 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: 0033:0x7f8e202b30d9
RSP: 002b:00007f8e1e50b028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f8e2053afa0 RCX: 00007f8e202b30d9
RDX: 0000000000000000 RSI: 0000200000000140 RDI: 0000200000000380
RBP: 00007f8e2034a024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000301400 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e2053b038 R14: 00007f8e2053afa0 R15: 00007ffc97285c28
 </TASK>
INFO: task syz.6.640:6761 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.640       state:D stack:23392 pid: 6761 ppid:  5669 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_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 reiserfs_write_lock_nested+0x5c/0xd0 fs/reiserfs/lock.c:78
 reiserfs_insert_item+0x36c/0xbe0 fs/reiserfs/stree.c:2220
 reiserfs_get_block+0x1aa0/0x4360 fs/reiserfs/inode.c:876
 reiserfs_get_blocks_direct_io+0xc5/0x2c0 fs/reiserfs/inode.c:530
 get_more_blocks fs/direct-io.c:673 [inline]
 do_direct_IO fs/direct-io.c:959 [inline]
 do_blockdev_direct_IO fs/direct-io.c:1276 [inline]
 __blockdev_direct_IO+0x142d/0x3b20 fs/direct-io.c:1368
 blockdev_direct_IO include/linux/fs.h:3345 [inline]
 reiserfs_direct_IO+0xeb/0x200 fs/reiserfs/inode.c:3263
 generic_file_direct_write+0x222/0x470 mm/filemap.c:3687
 __generic_file_write_iter+0x2b2/0x4e0 mm/filemap.c:3869
 generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944
 do_iter_readv_writev+0x47d/0x5f0 fs/read_write.c:-1
 do_iter_write+0x1f8/0x7a0 fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x241/0x3a0 fs/read_write.c:1025
 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: 0033:0x7f8e202b30d9
RSP: 002b:00007f8e1e4ea028 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f8e2053b090 RCX: 00007f8e202b30d9
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000006
RBP: 00007f8e2034a024 R08: 0000000000000000 R09: 0000000000000003
R10: 0000000000007a00 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e2053b128 R14: 00007f8e2053b090 R15: 00007ffc97285c28
 </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
3 locks held by kworker/1:2/1107:
 #0: ffff88802b23c538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90004bd7d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1530 net/ipv6/addrconf.c:4120
1 lock held by udevd/3559:
2 locks held by dhcpcd/3851:
 #0: ffff88801bc15690 (nlk_cb_mutex-ROUTE){+.+.}-{3:3}, at: __netlink_dump_start+0xf5/0x720 net/netlink/af_netlink.c:2363
 #1: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: netlink_dump+0x70a/0xdd0 net/netlink/af_netlink.c:2290
2 locks held by getty/3949:
 #0: ffff88814cfa1098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002d032e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by syz-executor/4193:
3 locks held by kworker/1:5/4231:
4 locks held by kworker/0:9/4259:
 #0: ffff888016c71138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000317fd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff8880551440e0 (&type->s_umount_key#86){++++}-{3:3}, at: flush_old_commits+0xce/0x310 fs/reiserfs/super.c:97
 #3: ffff8880262e3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
3 locks held by kworker/1:7/4276:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900032afd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff88807af61240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x283/0x3380 drivers/net/netdevsim/fib.c:1480
3 locks held by kworker/u4:10/4363:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900032ffd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
1 lock held by syz.6.640/6730:
 #0: ffff888054c00980 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #0: ffff888054c00980 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: lock_mount+0x60/0x2a0 fs/namespace.c:2260
3 locks held by syz.6.640/6761:
 #0: ffff888055144460 (sb_writers#26){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:927 [inline]
 #0: ffff888055144460 (sb_writers#26){.+.+}-{0:0}, at: do_pwritev+0x22a/0x3a0 fs/read_write.c:1025
 #1: ffff888054c00980 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff888054c00980 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: generic_file_write_iter+0x7e/0x1b0 mm/filemap.c:3941
 #2: ffff8880262e3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock_nested+0x5c/0xd0 fs/reiserfs/lock.c:78
3 locks held by syz.6.640/6763:
1 lock held by syz-executor/7047:
5 locks held by syz.7.1079/8597:
1 lock held by syz-executor/8689:
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz-executor/8716:
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz.1.1113/8732:
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by syz.1.1113/8733:
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
2 locks held by syz.8.1116/8742:
 #0: ffffffff8d4aa0b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
 #1: ffffffff8d44d488 (rtnl_mutex){+.+.}-{3:3}, at: ethnl_set_features+0x215/0xa70 net/ethtool/features.c:237

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

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>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6763 Comm: syz.6.640 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 42 ba 24 fd 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 e3 dc 69 fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 44 89 f9 80 e1 07 38 c1 7c aa 4c
RSP: 0018:ffffc90002f7e7f8 EFLAGS: 00000002
RAX: 1ffffffff2cc3760 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000020 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520005efcf4 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff9661b8c0 R15: 0000000000000000
FS:  00007f8e1e4c96c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f728322f6c8 CR3: 0000000056160000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:116 [inline]
 wait_for_xmitr+0x41/0x240 drivers/tty/serial/8250/8250_port.c:2069
 serial8250_console_putchar+0x1a/0x50 drivers/tty/serial/8250/8250_port.c:3315
 uart_console_write+0xaa/0x100 drivers/tty/serial/serial_core.c:1981
 serial8250_console_write+0xb90/0xf50 drivers/tty/serial/8250/8250_port.c:3392
 call_console_drivers kernel/printk/printk.c:-1 [inline]
 console_unlock+0xb47/0x10f0 kernel/printk/printk.c:2744
 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
 _printk+0xda/0x130 kernel/printk/printk.c:2299
 __reiserfs_warning+0x16c/0x1b0 fs/reiserfs/prints.c:290
 reiserfs_read_bitmap_block+0x21f/0x6a0 fs/reiserfs/bitmap.c:1434
 scan_bitmap_block+0x1a5/0xe30 fs/reiserfs/bitmap.c:164
 scan_bitmap fs/reiserfs/bitmap.c:391 [inline]
 allocate_without_wrapping_disk fs/reiserfs/bitmap.c:1161 [inline]
 blocknrs_and_prealloc_arrays_from_search_start fs/reiserfs/bitmap.c:1274 [inline]
 reiserfs_allocate_blocknrs+0x27c7/0x4f00 fs/reiserfs/bitmap.c:1375
 reiserfs_new_unf_blocknrs2 fs/reiserfs/reiserfs.h:3377 [inline]
 _allocate_block fs/reiserfs/inode.c:649 [inline]
 reiserfs_get_block+0x26de/0x4360 fs/reiserfs/inode.c:764
 __block_write_begin_int+0x565/0x15d0 fs/buffer.c:2012
 reiserfs_write_begin+0x353/0x820 fs/reiserfs/inode.c:2790
 generic_cont_expand_simple+0xf0/0x1a0 fs/buffer.c:2362
 reiserfs_setattr+0x3f5/0x10d0 fs/reiserfs/inode.c:3319
 notify_change+0xbc6/0xee0 fs/attr.c:505
 do_truncate+0x1ac/0x240 fs/open.c:65
 vfs_truncate+0x262/0x2f0 fs/open.c:111
 do_sys_truncate+0xf2/0x1c0 fs/open.c:134
 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: 0033:0x7f8e202b30d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8e1e4c9028 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f8e2053b180 RCX: 00007f8e202b30d9
RDX: 0000000000000000 RSI: 0000000000008da6 RDI: 0000200000000940
RBP: 00007f8e2034a024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e2053b218 R14: 00007f8e2053b180 R15: 00007ffc97285c28
 </TASK>