syzbot
INFO: task hung in jbd2_journal_commit_transaction (2)
Status:
upstream: reported on 2026/08/05 22:06
Reported-by: syzbot+8d4e4885d6259adfc43e@syzkaller.appspotmail.com
First crash: 2d01h, last: 7h06m
Sample crash report:
INFO: task jbd2/sda1-8:5103 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:jbd2/sda1-8 state:D stack:26024 pid:5103 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
io_schedule+0x80/0xd0 kernel/sched/core.c:9024
bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9f/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x13c/0x190 kernel/sched/wait_bit.c:64
wait_on_buffer include/linux/buffer_head.h:373 [inline]
jbd2_journal_commit_transaction+0x2e8d/0x5ad0 fs/jbd2/commit.c:815
kjournald2+0x40f/0x810 fs/jbd2/journal.c:201
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
INFO: task syz-executor:5774 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:22408 pid:5774 ppid:5773 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
io_schedule+0x80/0xd0 kernel/sched/core.c:9024
bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9f/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x13c/0x190 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x5c9/0xe00 fs/jbd2/transaction.c:1096
jbd2_journal_get_write_access+0x10c/0x140 fs/jbd2/transaction.c:1231
__ext4_journal_get_write_access+0x208/0x6d0 fs/ext4/ext4_jbd2.c:241
ext4_reserve_inode_write+0x205/0x2a0 fs/ext4/inode.c:5933
__ext4_mark_inode_dirty+0x13f/0x6d0 fs/ext4/inode.c:6107
ext4_dirty_inode+0xcb/0x110 fs/ext4/inode.c:6144
__mark_inode_dirty+0x2cc/0xc90 fs/fs-writeback.c:2522
generic_update_time fs/inode.c:1981 [inline]
inode_update_time fs/inode.c:1994 [inline]
__file_update_time fs/inode.c:2180 [inline]
file_update_time+0x187/0x1a0 fs/inode.c:2210
ext4_page_mkwrite+0x1f9/0x11a0 fs/ext4/inode.c:6262
do_page_mkwrite+0x153/0x3f0 mm/memory.c:2951
wp_page_shared mm/memory.c:3311 [inline]
do_wp_page+0xd4d/0x34d0 mm/memory.c:3396
handle_pte_fault mm/memory.c:5063 [inline]
__handle_mm_fault mm/memory.c:5188 [inline]
handle_mm_fault+0x1306/0x4a50 mm/memory.c:5353
do_user_addr_fault+0x736/0x12d0 arch/x86/mm/fault.c:1371
handle_page_fault arch/x86/mm/fault.c:1463 [inline]
exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f540a67c662
RSP: 002b:00007ffc46166cd0 EFLAGS: 00010202
RAX: 00007f540859c000 RBX: 000055555eb19f70 RCX: 0000000000000005
RDX: 00000000000022c4 RSI: 000055555eb18a58 RDI: 0000000000000020
RBP: 00007ffc461671d0 R08: 000055555eb18a58 R09: 0000000000000093
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffc46167010
R13: 00007ffc46166e00 R14: 585858582e7a7973 R15: 00007ffc46166d50
</TASK>
INFO: task syz.3.295:6863 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.295 state:D stack:27560 pid:6863 ppid:5792 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
io_schedule+0x80/0xd0 kernel/sched/core.c:9024
bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9f/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x13c/0x190 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x5c9/0xe00 fs/jbd2/transaction.c:1096
jbd2_journal_get_write_access+0x10c/0x140 fs/jbd2/transaction.c:1231
__ext4_journal_get_write_access+0x208/0x6d0 fs/ext4/ext4_jbd2.c:241
ext4_reserve_inode_write+0x205/0x2a0 fs/ext4/inode.c:5933
__ext4_mark_inode_dirty+0x13f/0x6d0 fs/ext4/inode.c:6107
ext4_dirty_inode+0xcb/0x110 fs/ext4/inode.c:6144
__mark_inode_dirty+0x2cc/0xc90 fs/fs-writeback.c:2522
generic_update_time fs/inode.c:1981 [inline]
inode_update_time fs/inode.c:1994 [inline]
__file_update_time fs/inode.c:2180 [inline]
file_update_time+0x187/0x1a0 fs/inode.c:2210
ext4_page_mkwrite+0x1f9/0x11a0 fs/ext4/inode.c:6262
do_page_mkwrite+0x153/0x3f0 mm/memory.c:2951
do_shared_fault mm/memory.c:4717 [inline]
do_fault mm/memory.c:4779 [inline]
do_pte_missing mm/memory.c:3689 [inline]
handle_pte_fault mm/memory.c:5047 [inline]
__handle_mm_fault mm/memory.c:5188 [inline]
handle_mm_fault+0x1a2c/0x4a50 mm/memory.c:5353
do_user_addr_fault+0x736/0x12d0 arch/x86/mm/fault.c:1371
handle_page_fault arch/x86/mm/fault.c:1463 [inline]
exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f6e99e6ba23
RSP: 002b:00007ffd2bc22c10 EFLAGS: 00010246
RAX: 00000000003ffde8 RBX: 0000000000000000 RCX: 0000001b2e464000
RDX: 0000001b2e424000 RSI: 0000000000400000 RDI: 00007f6e9a1e0708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffd2bc22ea0
</TASK>
INFO: task syz.1.294:6866 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.294 state:D stack:27560 pid:6866 ppid:5790 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
io_schedule+0x80/0xd0 kernel/sched/core.c:9024
bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9f/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x13c/0x190 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x5c9/0xe00 fs/jbd2/transaction.c:1096
jbd2_journal_get_write_access+0x10c/0x140 fs/jbd2/transaction.c:1231
__ext4_journal_get_write_access+0x208/0x6d0 fs/ext4/ext4_jbd2.c:241
ext4_reserve_inode_write+0x205/0x2a0 fs/ext4/inode.c:5933
__ext4_mark_inode_dirty+0x13f/0x6d0 fs/ext4/inode.c:6107
ext4_dirty_inode+0xcb/0x110 fs/ext4/inode.c:6144
__mark_inode_dirty+0x2cc/0xc90 fs/fs-writeback.c:2522
generic_update_time fs/inode.c:1981 [inline]
inode_update_time fs/inode.c:1994 [inline]
__file_update_time fs/inode.c:2180 [inline]
file_update_time+0x187/0x1a0 fs/inode.c:2210
ext4_page_mkwrite+0x1f9/0x11a0 fs/ext4/inode.c:6262
do_page_mkwrite+0x153/0x3f0 mm/memory.c:2951
do_shared_fault mm/memory.c:4717 [inline]
do_fault mm/memory.c:4779 [inline]
do_pte_missing mm/memory.c:3689 [inline]
handle_pte_fault mm/memory.c:5047 [inline]
__handle_mm_fault mm/memory.c:5188 [inline]
handle_mm_fault+0x1a2c/0x4a50 mm/memory.c:5353
do_user_addr_fault+0x736/0x12d0 arch/x86/mm/fault.c:1371
handle_page_fault arch/x86/mm/fault.c:1463 [inline]
exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7ff3dba6ba23
RSP: 002b:00007ffc5e4ed830 EFLAGS: 00010246
RAX: 00000000003ffde8 RBX: 0000000000000000 RCX: 0000001b2e264000
RDX: 0000001b2e224000 RSI: 0000000000400000 RDI: 00007ff3dbde0708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffc5e4edac0
</TASK>
INFO: task syz-executor:6869 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21800 pid:6869 ppid:6858 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x15ae/0x4660 kernel/sched/core.c:6701
schedule+0xbd/0x170 kernel/sched/core.c:6775
io_schedule+0x80/0xd0 kernel/sched/core.c:9024
bit_wait_io+0x11/0xd0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x9f/0x2c0 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0x13c/0x190 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x5c9/0xe00 fs/jbd2/transaction.c:1096
jbd2_journal_get_write_access+0x10c/0x140 fs/jbd2/transaction.c:1231
__ext4_journal_get_write_access+0x208/0x6d0 fs/ext4/ext4_jbd2.c:241
__ext4_new_inode+0x13f2/0x3ad0 fs/ext4/ialloc.c:1099
ext4_mkdir+0x40b/0xc90 fs/ext4/namei.c:3066
vfs_mkdir+0x2a5/0x470 fs/namei.c:4168
do_mkdirat+0x1dc/0x450 fs/namei.c:4191
__do_sys_mkdirat fs/namei.c:4206 [inline]
__se_sys_mkdirat fs/namei.c:4204 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4204
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff0f659cf47
RSP: 002b:00007fff8e4393c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007ff0f6634a68 RCX: 00007ff0f659cf47
RDX: 00000000000001ff RSI: 00007ff0f6634a68 RDI: 00000000ffffff9c
RBP: 00007ff0f68267b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008
R13: 0000000000000003 R14: 00007fff8e439638 R15: 0000000000000000
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/29:
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
#0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5531:
#0: ffff88802d8a50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
3 locks held by syz-executor/5774:
#0: ffff88807b22a7a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline]
#0: ffff88807b22a7a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline]
#0: ffff88807b22a7a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6261
#2: ffff88807e9a8990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
3 locks held by syz.3.295/6863:
#0: ffff88807f4a94a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline]
#0: ffff88807f4a94a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline]
#0: ffff88807f4a94a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6261
#2: ffff88807e9a8990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
3 locks held by syz.1.294/6866:
#0: ffff888019aa8b20 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline]
#0: ffff888019aa8b20 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline]
#0: ffff888019aa8b20 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline]
#1: ffff88807e99c510 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6261
#2: ffff88807e9a8990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
3 locks held by syz-executor/6869:
#0: ffff88807e99c418 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
#1: ffff88807422ac10 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
#1: ffff88807422ac10 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x20f/0x450 fs/namei.c:3937
#2: ffff88807e9a8990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 29 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+0x18c/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xf59/0xfa0 kernel/hung_task.c:379
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 49 Comm: kworker/u4:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
RIP: 0010:lookup_object lib/debugobjects.c:196 [inline]
RIP: 0010:lookup_object_or_alloc lib/debugobjects.c:565 [inline]
RIP: 0010:debug_object_assert_init+0xe0/0x300 lib/debugobjects.c:945
Code: fd 4c 89 34 24 4c 8b 6d 00 45 31 f6 eb 07 4d 8b 6d 00 41 ff c6 4d 85 ed 74 3c 4d 8d 65 18 4c 89 e0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 e7 e8 36 ce a6 fd 49 39 1c 24 0f 84 ea 00 00 00 4c 89
RSP: 0018:ffffc90000b9f8e8 EFLAGS: 00000046
RAX: 1ffff1100574409d RBX: ffff888041d3dac0 RCX: 0000000000000001
RDX: ffffffff9758c248 RSI: 0000000000000004 RDI: ffffc90000b9f7c0
RBP: ffffffff9758c238 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000173ef8 R12: ffff88802ba204e8
R13: ffff88802ba204d0 R14: 0000000000000003 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005581b763f168 CR3: 000000000cf32000 CR4: 00000000003506e0
Call Trace:
<TASK>
debug_timer_assert_init kernel/time/timer.c:792 [inline]
debug_assert_init kernel/time/timer.c:837 [inline]
__mod_timer+0x55/0xd60 kernel/time/timer.c:1020
mod_peer_timer+0x17a/0x250 drivers/net/wireguard/timers.c:37
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:36 [inline]
wg_packet_handshake_send_worker+0x1b5/0x360 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2657 [inline]
process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
* Struck through repros no longer work on HEAD.