INFO: task syz.4.523:6036 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.523 state:D stack:27488 pid: 6036 ppid: 4188 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
io_schedule+0x7c/0xd0 kernel/sched/core.c:8503
bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
__wait_on_bit kernel/sched/wait_bit.c:49 [inline]
out_of_line_wait_on_bit+0x15e/0x200 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
__wait_on_buffer fs/buffer.c:122 [inline]
wait_on_buffer include/linux/buffer_head.h:390 [inline]
__bread_slow fs/buffer.c:1181 [inline]
__bread_gfp+0x2c2/0x380 fs/buffer.c:1384
sb_bread include/linux/buffer_head.h:337 [inline]
befs_fill_super+0x764/0xe80 fs/befs/linuxvfs.c:855
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3025
do_mount fs/namespace.c:3368 [inline]
__do_sys_mount fs/namespace.c:3576 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3553
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: 0033:0x7fd4bf1f3ec9
RSP: 002b:00007fd4bd45b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fd4bf44afa0 RCX: 00007fd4bf1f3ec9
RDX: 00002000000002c0 RSI: 0000200000000280 RDI: 00002000000001c0
RBP: 00007fd4bf276f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd4bf44b038 R14: 00007fd4bf44afa0 R15: 00007fffc3c62f38
INFO: task syz.4.523:6038 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.523 state:D stack:29088 pid: 6038 ppid: 4188 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11bb/0x4390 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
rwsem_down_read_slowpath+0x528/0x990 kernel/locking/rwsem.c:1055
__down_read_common kernel/locking/rwsem.c:1239 [inline]
__down_read kernel/locking/rwsem.c:1252 [inline]
down_read+0x96/0x2e0 kernel/locking/rwsem.c:1500
get_super+0x102/0x200 fs/super.c:789
fsync_bdev+0x13/0xb0 block/bdev.c:214
blkdev_flushbuf block/ioctl.c:353 [inline]
blkdev_common_ioctl+0xdca/0x1c70 block/ioctl.c:478
blkdev_ioctl+0x295/0x690 block/ioctl.c:598
block_ioctl+0xac/0xf0 block/fops.c:496
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7fd4bf1f3ec9
RSP: 002b:00007fd4bd43a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd4bf44b090 RCX: 00007fd4bf1f3ec9
RDX: 0000200000000040 RSI: 0000000000001261 RDI: 0000000000000004
RBP: 00007fd4bf276f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd4bf44b128 R14: 00007fd4bf44b090 R15: 00007fffc3c62f38
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11c660 (
rcu_read_lock
){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
1 lock held by udevd/3559:
#0: ffff888020222118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x157/0xa60 block/bdev.c:820
2 locks held by getty/3948:
#0:
ffff88802bf0f098 (&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+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
4 locks held by kworker/0:14/5940:
1 lock held by syz.4.523/6036:
#0: ffff88807de160e0 (&type->s_umount_key#57/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
1 lock held by syz.4.523/6038:
#0: ffff88807de160e0 (&type->s_umount_key#58){.+.+}-{3:3}, at: get_super+0x102/0x200 fs/super.c:789
1 lock held by syz.5.999/8101:
#0: ffffffff8c120ff0 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0xa1/0x4b0 kernel/rcu/tree.c:4043
2 locks held by syz.3.1236/9354:
#0: ffff8880209ac518 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf9/0x7d0 block/bdev.c:915
#1: ffff888020930468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_release+0x4d/0x1f0 drivers/block/loop.c:2071
1 lock held by syz.1.1238/9356:
#0: ffff888147782468 (&lo->lo_mutex){+.+.}-{3:3}, at: loop_set_status+0x7c/0x9b0 drivers/block/loop.c:1522
2 locks held by syz.1.1238/9357:
#0: ffff888020222118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x157/0xa60 block/bdev.c:820
#1: ffff888147782468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_open+0x6a/0x100 drivers/block/loop.c:2056
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
nmi_cpu_backtrace+0x397/0x3d0 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+0xe0f/0xe50 kernel/hung_task.c:369
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9356 Comm: syz.1.1238 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 62 4f 32 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 53 b7 76 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:ffffc90003d76bf8 EFLAGS: 00000006
RAX: 1ffffffff2c7d505 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 000000000003a56b RDI: 000000000003a56c
RBP: ffffc90003d76dd0 R08: 0000000000000004 R09: 0000000000000003
R10: fffff520007aed60 R11: 1ffff920007aed60 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff963ea820 R15: 0000000000000000
FS: 00007fda79f8a6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb2041d81e0 CR3: 000000005fab9000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
serial_port_in include/linux/serial_core.h:344 [inline]
serial8250_console_write+0x241/0xf80 drivers/tty/serial/8250/8250_port.c:3367
call_console_drivers kernel/printk/printk.c:-1 [inline]
console_unlock+0xc86/0x1200 kernel/printk/printk.c:2744
vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
_printk+0xcc/0x110 kernel/printk/printk.c:2299
blk_add_partition block/partitions/core.c:576 [inline]
blk_add_partitions block/partitions/core.c:660 [inline]
bdev_disk_changed+0xf36/0x16b0 block/partitions/core.c:702
loop_reread_partitions drivers/block/loop.c:681 [inline]
loop_set_status+0x768/0x9b0 drivers/block/loop.c:1590
lo_ioctl+0xc27/0x1cf0 drivers/block/loop.c:-1
blkdev_ioctl+0x33c/0x690 block/ioctl.c:604
block_ioctl+0xac/0xf0 block/fops.c:496
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7fda7bd43acb
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007fda79f89d60 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fda79f89df0 RCX: 00007fda7bd43acb
RDX: 00007fda79f89f00 RSI: 0000000000004c04 RDI: 0000000000000007
RBP: 00007fda79f89f00 R08: 0000000000000000 R09: 0000000000001099
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00007fda7bf9b128 R14: 00007fda7bf9b090 R15: 00007fff56bc7dc8