INFO: task hung in start_this_handle

Status: upstream: reported on 2026/08/05 01:43
Reported-by: syzbot+73815e1a105d0765d1d5@syzkaller.appspotmail.com
First crash: 6d10h, last: 6d10h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 INFO: task hung in start_this_handle 1 1 3d19h 3d19h 0/2 upstream: reported on 2026/08/07 16:33
upstream INFO: task hung in start_this_handle (2) ext4 1 1 1659d 1659d 0/29 closed as invalid on 2022/02/07 19:09
upstream INFO: task hung in start_this_handle (3) ext4 1 7 673d 700d 0/29 auto-obsoleted due to no activity on 2025/01/04 20:07
upstream INFO: task hung in start_this_handle ext4 1 3 2862d 2870d 0/29 auto-closed as invalid on 2019/04/07 23:35

Sample crash report:
INFO: task kworker/u4:2:37 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:21072 pid:37    ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 add_transaction_credits fs/jbd2/transaction.c:315 [inline]
 start_this_handle+0xf89/0x2240 fs/jbd2/transaction.c:422
 jbd2__journal_start+0x2b7/0x5a0 fs/jbd2/transaction.c:520
 __ext4_journal_start_sb+0x187/0x3d0 fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_writepages+0xda9/0x2e70 fs/ext4/inode.c:2840
 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_start_all fs/fs-writeback.c:2262 [inline]
 wb_do_writeback fs/fs-writeback.c:2288 [inline]
 wb_workfn+0x964/0xee0 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
 </TASK>
INFO: task syz-executor:4260 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:22192 pid:4260  ppid:4259   flags:0x00004002
Call Trace:
 <TASK>
 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: 0033:0x7f030fc70123
RSP: 002b:00007fff370c2ac0 EFLAGS: 00010202
RAX: 00007f0309df4a9c RBX: 00007fff370c2bf0 RCX: 0000000000000000
RDX: 00007f0309df4a98 RSI: 0000000000000008 RDI: 00007fff370c2bf0
RBP: 00000000000003e6 R08: 0000000000000000 R09: 0000000000000000
R10: 00007fff370c2bd0 R11: 0000000000000000 R12: 0000000000000000
R13: 000000000000b564 R14: ffffffffffff4a9c R15: 0000000000000000
 </TASK>
INFO: task syz.4.19:4433 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.19        state:D stack:27696 pid:4433  ppid:4279   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 wb_wait_for_completion+0x16f/0x290 fs/fs-writeback.c:191
 sync_inodes_sb+0x1c5/0xa10 fs/fs-writeback.c:2807
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 ksys_sync_helper+0x13/0xa0 kernel/power/main.c:63
 enter_state kernel/power/suspend.c:583 [inline]
 pm_suspend+0x1b4/0x9a0 kernel/power/suspend.c:626
 state_store+0x202/0x290 kernel/power/main.c:639
 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 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: 0033:0x7f517139e019
RSP: 002b:00007f516f5f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5171625fa0 RCX: 00007f517139e019
RDX: 0000000000000003 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f517143500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5171626038 R14: 00007f5171625fa0 R15: 00007ffcdfce4228
 </TASK>
INFO: task syz-executor:4437 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:22384 pid:4437  ppid:4420   flags:0x00004000
Call Trace:
 <TASK>
 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_new_inode+0x1220/0x3b50 fs/ext4/ialloc.c:1099
 ext4_mkdir+0x407/0xc90 fs/ext4/namei.c:3066
 vfs_mkdir+0x386/0x570 fs/namei.c:4114
 do_mkdirat+0x1d8/0x440 fs/namei.c:4139
 __do_sys_mkdirat fs/namei.c:4154 [inline]
 __se_sys_mkdirat fs/namei.c:4152 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4152
 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: 0033:0x7fc1e7f9ce87
RSP: 002b:00007ffeadb87998 EFLAGS: 00000206 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fc1e8034a50 RCX: 00007fc1e7f9ce87
RDX: 00000000000001ff RSI: 00007fc1e8034a50 RDI: 00000000ffffff9c
RBP: 00007fc1e82267b8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000008
R13: 0000000000000003 R14: 00007ffeadb87c08 R15: 0000000000000000
 </TASK>
INFO: task syz.0.20:4459 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.20        state:D stack:26928 pid:4459  ppid:4274   flags:0x00004004
Call Trace:
 <TASK>
 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: 0033:0x7f4cefa6b9e3
RSP: 002b:00007ffe98ed6a60 EFLAGS: 00010246
RAX: 00000000003ffde8 RBX: 0000000000000000 RCX: 0000001b2f864000
RDX: 0000001b2f824000 RSI: 0000000000400000 RDI: 00007f4cefde0708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffe98ed6cf0
 </TASK>
INFO: task syz.3.21:4460 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.21        state:D stack:27632 pid:4460  ppid:4273   flags:0x00004004
Call Trace:
 <TASK>
 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: 0033:0x7fd86ec6b9e3
RSP: 002b:00007ffd188b35e0 EFLAGS: 00010246
RAX: 00000000003ffde8 RBX: 0000000000000000 RCX: 0000001b2fb64000
RDX: 0000001b2fb24000 RSI: 0000000000400000 RDI: 00007fd86efe0708
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffd188b3870
 </TASK>

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/27:
 #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
4 locks held by kworker/u4:2/37:
 #0: ffff888143e5f938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90000ae7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff88814de6c0e0 (&type->s_umount_key#32){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
 #3: ffff88814de6ec18 (&sbi->s_writepages_rwsem){.+.+}-{0:0}, at: ext4_writepages+0x213/0x2e70 fs/ext4/inode.c:2717
1 lock held by syslogd/3621:
 #0: ffff8880b8f3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:538
1 lock held by klogd/3628:
 #0: ffff8880b8f3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:538
2 locks held by getty/4027:
 #0: ffff88814d364098 (&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
3 locks held by syz-executor/4260:
 #0: ffff888019277958 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff888019277958 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff888019277958 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1995 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6273
 #2: ffff88814de70990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
2 locks held by kworker/u4:5/4300:
 #0: ffff8880b8f3ad18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x25/0x130 kernel/sched/core.c:538
 #1: ffff8880b8f27888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x36b/0x740 kernel/sched/psi.c:987
7 locks held by syz.4.19/4433:
 #0: ffff88807c6e80e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
 #1: ffff88807ca80460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
 #2: ffff888024a01088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1d8/0x520 fs/kernfs/file.c:343
 #3: ffff888140138cb8 (kn->active#61){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #3: ffff888140138cb8 (kn->active#61){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x520 fs/kernfs/file.c:344
 #4: ffffffff8c9e2e28 (system_transition_mutex){+.+.}-{3:3}, at: enter_state kernel/power/suspend.c:575 [inline]
 #4: ffffffff8c9e2e28 (system_transition_mutex){+.+.}-{3:3}, at: pm_suspend+0x3bc/0x9a0 kernel/power/suspend.c:626
 #5: ffff88814de6c0e0 (&type->s_umount_key#32){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #6: ffff8880274fe820 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #6: ffff8880274fe820 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2805
3 locks held by syz-executor/4437:
 #0: ffff88814de6c460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff8880747f4a38 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:793 [inline]
 #1: ffff8880747f4a38 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x20b/0x450 fs/namei.c:3884
 #2: ffff88814de70990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
3 locks held by syz.0.20/4459:
 #0: ffff88802ff388d8 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff88802ff388d8 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff88802ff388d8 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1995 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6273
 #2: ffff88814de70990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463
3 locks held by syz.3.21/4460:
 #0: ffff88802ff3f958 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #0: ffff88802ff3f958 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #0: ffff88802ff3f958 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2f0 mm/memory.c:5382
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1891 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1995 [inline]
 #1: ffff88814de6c558 (sb_pagefaults){.+.+}-{0:0}, at: ext4_page_mkwrite+0x192/0x10d0 fs/ext4/inode.c:6273
 #2: ffff88814de70990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x2014/0x2240 fs/jbd2/transaction.c:463

=============================================

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+0x188/0x24e 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
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3628 Comm: klogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:sock_error include/net/sock.h:2595 [inline]
RIP: 0010:sock_alloc_send_pskb+0x1dd/0x9a0 net/core/sock.c:2744
Code: 24 38 42 c7 44 30 04 f8 f8 f8 f8 42 c6 44 30 08 f8 48 8b 44 24 78 42 0f b6 04 30 84 c0 0f 85 d8 05 00 00 48 8b 44 24 10 8b 18 <31> ff 89 de e8 ea 93 54 f9 85 db 0f 85 8b 05 00 00 e8 7d 90 54 f9
RSP: 0018:ffffc900032b7980 EFLAGS: 00000246
RAX: ffff88807e21dbe0 RBX: 0000000000000000 RCX: ffffc900032b7a78
RDX: 1ffff1100fc43b8c RSI: 1ffff1100fc43b4e RDI: 1ffff1100fc43b4d
RBP: ffffc900032b7b10 R08: 1ffff1100fc43b0c R09: 1ffff1100fc43b8e
R10: dffffc0000000000 R11: ffffed1002f1ff02 R12: 7fffffffffffffff
R13: ffff88807e21da48 R14: dffffc0000000000 R15: ffff88807e21d800
FS:  00007f47f5bcdc80(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561320127168 CR3: 000000007e459000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 unix_dgram_sendmsg+0x5c1/0x16f0 net/unix/af_unix.c:1945
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x497/0x650 net/socket.c:2153
 __do_sys_sendto net/socket.c:2165 [inline]
 __se_sys_sendto net/socket.c:2161 [inline]
 __x64_sys_sendto+0xda/0xf0 net/socket.c:2161
 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: 0033:0x7f47f5d1d407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fffe0e53100 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f47f5bcdc80 RCX: 00007f47f5d1d407
RDX: 000000000000005c RSI: 00007fffe0e53240 RDI: 0000000000000003
RBP: 00007fffe0e53670 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007fffe0e53688
R13: 00007fffe0e53240 R14: 0000000000000041 R15: 00007fffe0e53240
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/05 01:43 linux-6.1.y fb28aa725e05 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in start_this_handle
* Struck through repros no longer work on HEAD.