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: 16h34m, last: 16h34m
Sample crash report:
INFO: task jbd2/sda1-8:5105 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:25736 pid:5105 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:5764 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:22888 pid:5764 ppid:5763 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: 0033:0x7fa4f907c662
RSP: 002b:00007ffd505e0d00 EFLAGS: 00010202
RAX: 00007fa4f6e70000 RBX: 0000555571dd1570 RCX: 0000000000000006
RDX: 0000000000002939 RSI: 0000555571dce9e8 RDI: 0000000000000040
RBP: 00007ffd505e1200 R08: 0000555571dcea28 R09: 0000000000000093
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffd505e1040
R13: 00007ffd505e0e30 R14: 585858582e7a7973 R15: 00007ffd505e0d80
</TASK>
INFO: task syz.6.979:9536 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.979 state:D stack:27048 pid:9536 ppid:7951 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: 0033:0x7f5eadc72789
RSP: 002b:00007ffe1ccb5790 EFLAGS: 00010202
RAX: 0000001b34c24000 RBX: 0000000000000000 RCX: 00000000003ffde8
RDX: 0000001b34c23ffc RSI: 00000000003ffde8 RDI: 00007f5eaeb55700
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f5eae012000
R10: 00007f5eaeb55700 R11: 0000000000000000 R12: 0000000000000000
R13: 00000000000141b7 R14: ffffffff813215fe R15: 00007f5eaeb55720
</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
3 locks held by kworker/u4:10/3488:
2 locks held by getty/5530:
#0: ffff8880317b20a0 (&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/5764:
#0: ffff88802964c420 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline]
#0: ffff88802964c420 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline]
#0: ffff88802964c420 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline]
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6261
#2: ffff88807e484990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
3 locks held by syz.6.979/9536:
#0: ffff888017c6a7a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline]
#0: ffff888017c6a7a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline]
#0: ffff888017c6a7a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline]
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline]
#1: ffff88807e480510 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6261
#2: ffff88807e484990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448
=============================================
NMI backtrace for cpu 1
CPU: 1 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 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: bat_events batadv_nc_worker
RIP: 0010:hlock_class kernel/locking/lockdep.c:223 [inline]
RIP: 0010:__lock_acquire+0x1047/0x7d80 kernel/locking/lockdep.c:5133
Code: 4c 8b 7c 24 18 0f 85 bd 02 00 00 48 83 7c 24 68 00 0f 84 f8 01 00 00 48 8b 84 24 88 00 00 00 48 8d 58 f8 48 89 d8 48 c1 e8 03 <42> 0f b6 04 00 84 c0 0f 85 eb 0f 00 00 8b 03 89 c3 81 e3 ff 1f 00
RSP: 0018:ffffc90000b9f700 EFLAGS: 00000806
RAX: 1ffff11003a4aca5 RBX: ffff88801d256528 RCX: 00000000709e4ba1
RDX: 00000000de2ebe07 RSI: 00000000b8540d1a RDI: ffffffff911eb5d8
RBP: ffffc90000b9f948 R08: dffffc0000000000 R09: 1ffffffff223d6bb
R10: dffffc0000000000 R11: fffffbfff223d6bc R12: 0000000046019e68
R13: ffff88801d255a00 R14: 0000000068699336 R15: ffff88801d256550
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c5eabd5660 CR3: 000000000cf32000 CR4: 00000000003506f0
Call Trace:
<TASK>
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:356 [inline]
batadv_nc_purge_paths+0xe2/0x3a0 net/batman-adv/network-coding.c:442
batadv_nc_worker+0x363/0x600 net/batman-adv/network-coding.c:722
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.