INFO: task kworker/u4:6:4361 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6 state:D stack:21952 pid:4361 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
schedule+0xb9/0x180 kernel/sched/core.c:6639
io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
rq_qos_wait+0x227/0x350 block/blk-rq-qos.c:282
__wbt_wait block/blk-wbt.c:522 [inline]
wbt_wait+0x384/0x650 block/blk-wbt.c:586
__rq_qos_throttle+0x61/0xa0 block/blk-rq-qos.c:66
rq_qos_throttle block/blk-rq-qos.h:207 [inline]
blk_mq_get_new_requests block/blk-mq.c:2924 [inline]
blk_mq_submit_bio+0x8ef/0x2100 block/blk-mq.c:3023
__submit_bio+0x1a2/0x290 block/blk-core.c:591
__submit_bio_noacct_mq block/blk-core.c:668 [inline]
submit_bio_noacct_nocheck+0x7f1/0xaa0 block/blk-core.c:697
ext4_io_submit+0xd8/0x140 fs/ext4/page-io.c:378
ext4_writepages+0xf76/0x2e70 fs/ext4/inode.c:2877
do_writepages+0x3c6/0x640 mm/page-writeback.c:2491
__writeback_single_inode+0x153/0x1170 fs/fs-writeback.c:1673
writeback_sb_inodes+0xad5/0x17f0 fs/fs-writeback.c:1964
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2035
wb_writeback+0x484/0xd40 fs/fs-writeback.c:2140
wb_check_old_data_flush fs/fs-writeback.c:2240 [inline]
wb_do_writeback fs/fs-writeback.c:2293 [inline]
wb_workfn+0xb68/0xee0 fs/fs-writeback.c:2321
process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task syz.0.252:4673 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.252 state:D stack:27632 pid:4673 ppid:4376 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5246 [inline]
__schedule+0x107f/0x4030 kernel/sched/core.c:6563
schedule+0xb9/0x180 kernel/sched/core.c:6639
io_schedule+0x7c/0xd0 kernel/sched/core.c:8799
bit_wait_io+0xd/0xc0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9b/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x138/0x190 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x605/0xf20 fs/jbd2/transaction.c:1115
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
__ext4_journal_get_write_access+0x24b/0x6e0 fs/ext4/ext4_jbd2.c:235
ext4_reserve_inode_write+0x201/0x290 fs/ext4/inode.c:5945
__ext4_mark_inode_dirty+0x161/0x760 fs/ext4/inode.c:6119
ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6156
__mark_inode_dirty+0x2e7/0xe80 fs/fs-writeback.c:2500
generic_update_time fs/inode.c:1946 [inline]
inode_update_time fs/inode.c:1959 [inline]
__file_update_time+0x21d/0x240 fs/inode.c:2147
file_update_time+0x2f3/0x370 fs/inode.c:2178
ext4_page_mkwrite+0x1a9/0x10d0 fs/ext4/inode.c:6274
do_page_mkwrite+0x16b/0x5c0 mm/memory.c:3009
do_shared_fault mm/memory.c:4694 [inline]
do_fault mm/memory.c:4762 [inline]
handle_pte_fault mm/memory.c:5029 [inline]
__handle_mm_fault mm/memory.c:5171 [inline]
handle_mm_fault+0x199c/0x3d40 mm/memory.c:5292
do_user_addr_fault+0x58e/0xb20 arch/x86/mm/fault.c:1338
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1482
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fe587c6b9e3
RSP: 002b:00007fff947d37e0 EFLAGS: 00010246
RAX: 000000000003fde8 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000001b2e324000 RSI: 0000000000040000 RDI: 00007fe587fe0708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007fff947d3a70
Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by getty/4029:
#0: ffff88802f977098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
4 locks held by kworker/u4:6/4361:
#0: ffff88801c657138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
#1: ffffc900032e7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
#2: ffff88807f4260e0 (&type->s_umount_key#31){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff88807f428c18 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x213/0x2e70 fs/ext4/inode.c:2717
3 locks held by syz.0.252/4673:
#0: ffff88802ce31058 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88802ce31058 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
#0: ffff88802ce31058 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
#1: ffff88807f426558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
#1: ffff88807f426558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1995 [inline]
#1: ffff88807f426558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6273
#2: ffff88807f42a990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
3 locks held by syz-executor/4677:
#0: ffff88807f426460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
#1: ffff888074f04030 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
#1: ffff888074f04030 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3884
#2: ffff88807f42a990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
nmi_cpu_backtrace+0x3e6/0x460 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+0xf0e/0xf50 kernel/hung_task.c:377
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3629 Comm: klogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:check_kcov_mode kernel/kcov.c:193 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:245 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x32/0x80 kernel/kcov.c:313
Code: b4 3d 80 7e 65 8b 0d b5 3d 80 7e 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 1c 16 00 00 00 74 52 8b 8a f8 15 00 00 <83> f9 03 75 47 48 8b 8a 00 16 00 00 44 8b 8a fc 15 00 00 49 c1 e1
RSP: 0018:ffffc900032a7828 EFLAGS: 00000246
RAX: ffffffff8a20fb7e RBX: ffff0a00ffffff0f RCX: 0000000000000000
RDX: ffff88807d4b9e00 RSI: 0000000000000020 RDI: 0000000000000029
RBP: ffffffff8a8cdea4 R08: ffff88807d4b9e00 R09: 0000000000000012
R10: 0000000000000012 R11: 0000000000000000 R12: 0000000000000020
R13: ffffc900032a7a01 R14: dffffc0000000000 R15: ffffffff8a8cdea2
FS: 00007fc7331dbc80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005643441ee168 CR3: 000000007f8a7000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
vsnprintf+0x59e/0x1c20 lib/vsprintf.c:2868
snprintf+0xe5/0x140 lib/vsprintf.c:2940
print_caller kernel/printk/printk.c:1283 [inline]
info_print_prefix+0x1fa/0x360 kernel/printk/printk.c:1302
record_print_text+0x17e/0x4a0 kernel/printk/printk.c:1349
syslog_print+0x3c7/0x630 kernel/printk/printk.c:1560
do_syslog+0x817/0x900 kernel/printk/printk.c:1679
__do_sys_syslog kernel/printk/printk.c:1771 [inline]
__se_sys_syslog kernel/printk/printk.c:1769 [inline]
__x64_sys_syslog+0x78/0x90 kernel/printk/printk.c:1769
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc7333a5a37
Code: 73 01 c3 48 8b 0d c1 f3 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 67 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 f3 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffd38b0bc98 EFLAGS: 00000206 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 00007fc733545490 RCX: 00007fc7333a5a37
RDX: 00000000000003ff RSI: 00007fc733545490 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000206 R12: 00007fc733545490
R13: 00007fc733522dfe R14: 00007fc733545525 R15: 00007fc733545525