INFO: task syz.4.12479:9702 blocked for more than 145 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.12479 state:D stack:25160 pid:9702 tgid:9702 ppid:9255 task_flags:0x400040 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7026
io_schedule+0x81/0xe0 kernel/sched/core.c:7871
folio_wait_bit_common+0x6b5/0xb90 mm/filemap.c:1330
folio_wait_writeback+0xb0/0x100 mm/page-writeback.c:3095
__filemap_fdatawait_range+0x147/0x230 mm/filemap.c:542
filemap_fdatawait_range+0x25/0x40 mm/filemap.c:568
filemap_fdatawait include/linux/pagemap.h:50 [inline]
__writeback_single_inode+0x1dc/0x1000 fs/fs-writeback.c:1729
writeback_single_inode+0x1db/0x640 fs/fs-writeback.c:1840
write_inode_now+0x160/0x1d0 fs/fs-writeback.c:2903
fuse_flush+0x26c/0x810 fs/fuse/file.c:460
filp_flush+0xc0/0x190 fs/open.c:1549
filp_close+0x1d/0x40 fs/open.c:1562
__range_close fs/file.c:767 [inline]
__do_sys_close_range fs/file.c:826 [inline]
__se_sys_close_range+0x35c/0x650 fs/file.c:790
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff919f6efc9
RSP: 002b:00007ffd2372e388 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007ff91a1c7da0 RCX: 00007ff919f6efc9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007ff91a1c7da0 R08: 0000000000000184 R09: 000000162372e67f
R10: 00007ff91a1c7cb0 R11: 0000000000000246 R12: 00000000002853d3
R13: 00007ff91a1c6090 R14: ffffffffffffffff R15: 00007ffd2372e4a0
</TASK>
INFO: task syz.4.12479:9704 blocked for more than 145 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.12479 state:D stack:24648 pid:9704 tgid:9702 ppid:9255 task_flags:0x400140 flags:0x00080003
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7026
io_schedule+0x81/0xe0 kernel/sched/core.c:7871
folio_wait_bit_common+0x6b5/0xb90 mm/filemap.c:1330
folio_wait_writeback+0xb0/0x100 mm/page-writeback.c:3095
__filemap_fdatawait_range+0x147/0x230 mm/filemap.c:542
file_write_and_wait_range+0x290/0x340 mm/filemap.c:801
fuse_fsync+0x127/0x310 fs/fuse/file.c:535
generic_write_sync include/linux/fs.h:3046 [inline]
fuse_cache_write_iter fs/fuse/file.c:1470 [inline]
fuse_file_write_iter+0xeee/0x10c0 fs/fuse/file.c:1783
do_iter_readv_writev+0x635/0x8d0 fs/read_write.c:-1
vfs_writev+0x323/0x970 fs/read_write.c:1057
do_writev+0x153/0x2d0 fs/read_write.c:1103
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff919f6efc9
RSP: 002b:00007ff9181d6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007ff91a1c5fa0 RCX: 00007ff919f6efc9
RDX: 0000000000000001 RSI: 0000200000000000 RDI: 0000000000000009
RBP: 00007ff919ff1f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff91a1c6038 R14: 00007ff91a1c5fa0 R15: 00007ffd2372e228
</TASK>
Showing all locks held in the system:
2 locks held by pr/legacy/17:
1 lock held by khungtaskd/38:
#0: ffffffff8d5aa800 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d5aa800 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8d5aa800 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5560:
#0: ffff88823bf288a0 (&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+0x444/0x1400 drivers/tty/n_tty.c:2222
5 locks held by kworker/u8:14/6204:
7 locks held by kworker/1:9/17441:
7 locks held by kworker/0:1/6244:
#0: ffff88813ff55138 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88813ff55138 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000ffe7ba0 ((work_completion)(&dev->request_module_wk)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000ffe7ba0 ((work_completion)(&dev->request_module_wk)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8e496d38 (em28xx_devlist_mutex){+.+.}-{4:4}, at: em28xx_init_extension+0x32/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1113
#3: ffff88806cec1e78 (&dev->lock#3){+.+.}-{4:4}, at: em28xx_v4l2_init+0xd7/0x2e80 drivers/media/usb/em28xx/em28xx-video.c:2530
#4: ffff88806cec0330 (i2c_register_adapter){+.+.}-{4:4}, at: i2c_lock_bus include/linux/i2c.h:809 [inline]
#4: ffff88806cec0330 (i2c_register_adapter){+.+.}-{4:4}, at: __i2c_lock_bus_helper drivers/i2c/i2c-core.h:46 [inline]
#4: ffff88806cec0330 (i2c_register_adapter){+.+.}-{4:4}, at: i2c_smbus_xfer+0x129/0x3c0 drivers/i2c/i2c-core-smbus.c:542
#5: ffff88806cec1d78 (em28xx_init_dev){+.+.}-{4:4}, at: em28xx_i2c_xfer+0x140/0x1ba0 drivers/media/usb/em28xx/em28xx-i2c.c:541
#6: ffff88806cec1ef8 (&dev->ctrl_urb_lock){+.+.}-{4:4}, at: em28xx_write_regs_req+0x14d/0x3e0 drivers/media/usb/em28xx/em28xx-core.c:147
2 locks held by kworker/u8:7/9314:
#0: ffff888140473938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff888140473938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000488fba0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000488fba0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
3 locks held by syz.4.12479/9704:
#0: ffff88805b91ef28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1232
#1: ffff888061506480 (sb_writers#13){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3111 [inline]
#1: ffff888061506480 (sb_writers#13){.+.+}-{0:0}, at: vfs_writev+0x28e/0x970 fs/read_write.c:1055
#2: ffff88803aef89b8 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
#2: ffff88803aef89b8 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: fuse_fsync+0x114/0x310 fs/fuse/file.c:528
2 locks held by syz.1.12693/10411:
#0: ffff8880615060d0 (&type->s_umount_key#54){++++}-{4:4}, at: __super_lock fs/super.c:59 [inline]
#0: ffff8880615060d0 (&type->s_umount_key#54){++++}-{4:4}, at: super_lock+0x2a9/0x3b0 fs/super.c:121
#1: ffff88803a7808c0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
#1: ffff88803a7808c0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x19b/0xa50 fs/fs-writeback.c:2871
3 locks held by syz.5.12897/11034:
#0: ffff888050362480 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:508
#1: ffff88803aefa278 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1025 [inline]
#1: ffff88803aefa278 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: filename_create+0x1f8/0x3c0 fs/namei.c:4226
#2: ffff88803aefa7f0 (&fi->mutex){+.+.}-{4:4}, at: fuse_lock_inode+0xd3/0x120 fs/fuse/inode.c:604
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf60/0xfa0 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 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 10/02/2025
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400
Code: e8 fe 01 ba 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 8f b9 1b fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 0a 61 bf 05 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc90000167870 EFLAGS: 00000202
RAX: 1ffffffff31d1d00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff98e8f0f0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8504bdd0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff98e8ee60 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888126df9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f79ff8ccf98 CR3: 0000000058dbc000 CR4: 00000000003526f0
Call Trace:
<TASK>
serial_in drivers/tty/serial/8250/8250.h:137 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:159 [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+0x11bd/0x1b40 drivers/tty/serial/8250/8250_port.c:3342
console_emit_next_record kernel/printk/printk.c:3091 [inline]
console_flush_all+0x666/0xb40 kernel/printk/printk.c:3199
__console_flush_and_unlock+0x9b/0x160 kernel/printk/printk.c:3258
legacy_kthread_func+0x13b/0x1a0 kernel/printk/printk.c:3611
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>