syzbot
INFO: task hung in jbd2_journal_commit_transaction
Status:
upstream: reported on 2026/08/05 05:38
Reported-by: syzbot+a6aabe9adc9f9269764d@syzkaller.appspotmail.com
First crash: 2d03h, last: 5h08m
Sample crash report:
INFO: task jbd2/sda1-8:3519 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:25872 pid: 3519 ppid: 2 flags:0x00004000
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
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+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_buffer include/linux/buffer_head.h:390 [inline]
jbd2_journal_commit_transaction+0x2f0b/0x5c30 fs/jbd2/commit.c:848
kjournald2+0x45a/0x900 fs/jbd2/journal.c:213
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
INFO: task syz-executor:4173 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:22896 pid: 4173 ppid: 4172 flags:0x00004002
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
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+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251
__ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235
ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866
__ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040
ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077
__mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480
generic_update_time+0x1cd/0x1f0 fs/inode.c:1881
inode_update_time fs/inode.c:1894 [inline]
file_update_time+0x3c0/0x440 fs/inode.c:2083
ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195
do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
wp_page_shared+0x163/0x6c0 mm/memory.c:3259
handle_pte_fault mm/memory.c:4668 [inline]
__handle_mm_fault mm/memory.c:4785 [inline]
handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883
do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
handle_page_fault arch/x86/mm/fault.c:1443 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7fafd915e790
RSP: 002b:00007ffc96d13a58 EFLAGS: 00010246
RAX: 00007fafd19ecff8 RBX: 00007ffc96d13bf0 RCX: 0000000000000006
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 00007fafd19ecff8
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 00007ffc96d13bd0 R11: 0000000000000000 R12: 0000000000001000
R13: 0000000000000ff8 R14: 0000000000000008 R15: 0000000000000000
</TASK>
INFO: task syz.3.606:6786 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.606 state:D stack:27440 pid: 6786 ppid: 4193 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
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+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251
__ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235
ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866
__ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040
ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077
__mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480
generic_update_time+0x1cd/0x1f0 fs/inode.c:1881
inode_update_time fs/inode.c:1894 [inline]
file_update_time+0x3c0/0x440 fs/inode.c:2083
ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195
do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
do_shared_fault mm/memory.c:4328 [inline]
do_fault mm/memory.c:4396 [inline]
handle_pte_fault mm/memory.c:4650 [inline]
__handle_mm_fault mm/memory.c:4785 [inline]
handle_mm_fault+0x1e47/0x4440 mm/memory.c:4883
do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
handle_page_fault arch/x86/mm/fault.c:1443 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7efd5cb8e729
RSP: 002b:00007ffc9ed430b0 EFLAGS: 00010202
RAX: 0000001b32723000 RBX: ffffffff81a8b8cc RCX: 0000001b32722ff8
RDX: 0000001b32324220 RSI: 0000000000000008 RDI: 00007efd5da71720
RBP: 00000000000001df R08: 00007efd5cf2c000 R09: 00007efd5cf2e000
R10: 0000000081a8b8d0 R11: 000000000000000e R12: 00007efd5cf42038
R13: 00000000000006de R14: ffffffff81a8b9ff R15: 00007efd5da71720
</TASK>
INFO: task syz.5.609:6794 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.609 state:D stack:27120 pid: 6794 ppid: 5111 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
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+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251
__ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235
ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866
__ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040
ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077
__mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480
generic_update_time+0x1cd/0x1f0 fs/inode.c:1881
inode_update_time fs/inode.c:1894 [inline]
file_update_time+0x3c0/0x440 fs/inode.c:2083
ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195
do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
do_shared_fault mm/memory.c:4328 [inline]
do_fault mm/memory.c:4396 [inline]
handle_pte_fault mm/memory.c:4650 [inline]
__handle_mm_fault mm/memory.c:4785 [inline]
handle_mm_fault+0x1e47/0x4440 mm/memory.c:4883
do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
handle_page_fault arch/x86/mm/fault.c:1443 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7fe04d90f789
RSP: 002b:00007ffc861725b0 EFLAGS: 00010202
RAX: 0000001b33b24000 RBX: 0000000000000000 RCX: 00000000005ffde8
RDX: 0000001b33b23ffc RSI: 00000000005ffde8 RDI: 00007fe04e7f2700
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007fe04dcaf000
R10: 00007fe04e7f2700 R11: 0000000000000000 R12: 0000000000000000
R13: 00000000000003b2 R14: ffffffff819d3f44 R15: 00007fe04e7f2720
</TASK>
INFO: task syz.0.607:6809 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.607 state:D stack:26704 pid: 6809 ppid: 4191 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
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+0x173/0x230 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
do_get_write_access+0x134/0xe40 fs/jbd2/transaction.c:1116
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1251
__ext4_journal_get_write_access+0x24d/0x6e0 fs/ext4/ext4_jbd2.c:235
ext4_reserve_inode_write+0x203/0x2e0 fs/ext4/inode.c:5866
__ext4_mark_inode_dirty+0x136/0x6c0 fs/ext4/inode.c:6040
ext4_dirty_inode+0xbf/0x100 fs/ext4/inode.c:6077
__mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480
generic_update_time+0x1cd/0x1f0 fs/inode.c:1881
inode_update_time fs/inode.c:1894 [inline]
file_update_time+0x3c0/0x440 fs/inode.c:2083
ext4_page_mkwrite+0x1bc/0x1250 fs/ext4/inode.c:6195
do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
do_shared_fault mm/memory.c:4328 [inline]
do_fault mm/memory.c:4396 [inline]
handle_pte_fault mm/memory.c:4650 [inline]
__handle_mm_fault mm/memory.c:4785 [inline]
handle_mm_fault+0x1e47/0x4440 mm/memory.c:4883
do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
handle_page_fault arch/x86/mm/fault.c:1443 [inline]
exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7f78e7b12a23
RSP: 002b:00007ffc713ebb50 EFLAGS: 00010246
RAX: 00000000003ffde8 RBX: 0000000000000000 RCX: 0000001b32064000
RDX: 0000001b32024000 RSI: 0000000000400000 RDI: 00007f78e7e87708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffc713ebde0
</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
2 locks held by getty/3943:
#0: ffff88802c7a4098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
3 locks held by syz-executor/4173:
#0: ffff88807c3c7128 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88807c3c7128 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194
#2: ffff88814d0d6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
2 locks held by kworker/u4:7/4351:
3 locks held by syz.3.606/6786:
#0: ffff8880798a7828 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff8880798a7828 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194
#2: ffff88814d0d6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
3 locks held by syz.5.609/6794:
#0: ffff88807e520828 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88807e520828 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194
#2: ffff88814d0d6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
3 locks held by syz.0.607/6809:
#0: ffff888016c6b228 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff888016c6b228 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1811 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1910 [inline]
#1: ffff88814d0d2558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1a5/0x1250 fs/ext4/inode.c:6194
#2: ffff88814d0d6990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x12d5/0x1560 fs/jbd2/transaction.c:462
=============================================
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: 4351 Comm: kworker/u4:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4702 [inline]
RIP: 0010:__lock_acquire+0x6f9/0x7b50 kernel/locking/lockdep.c:4962
Code: 70 01 00 00 44 89 fb 81 e3 ff ff ff 7f 83 f8 31 73 45 48 8d 04 9b 49 8d 9c c5 10 0b 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 00 <84> c0 75 44 8b 1b 48 8b 44 24 30 42 0f b6 04 00 84 c0 75 54 48 8b
RSP: 0018:ffffc900033cf6a0 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff888079b4a920 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901ee0c0
RBP: ffffc900033cf8d0 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: 0000000000000000
R13: ffff888079b49dc0 R14: 0000000000000004 R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056348d319168 CR3: 000000002b7b7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:769 [inline]
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:849 [inline]
batadv_iv_ogm_schedule+0x434/0x1000 net/batman-adv/bat_iv_ogm.c:908
batadv_iv_send_outstanding_bat_ogm_packet+0x6e9/0x800 net/batman-adv/bat_iv_ogm.c:1805
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
* Struck through repros no longer work on HEAD.