syzbot


INFO: task jbd2/sda1-NUM:NUM blocked in I/O wait for more than NUM seconds.

Status: moderation: reported on 2026/04/24 13:13
Reported-by: syzbot+bc32a385f0bbe3e3d971@syzkaller.appspotmail.com
First crash: 5d11h, last: 1d12h

Sample crash report:
INFO: task jbd2/sda1-8:5176 blocked in I/O wait for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:jbd2/sda1-8     state:D stack:26072 pid:5176  tgid:5176  ppid:2      task_flags:0x240040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 io_schedule+0x8a/0xf0 kernel/sched/core.c:8109
 bit_wait_io+0xd/0xe0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0x65/0x180 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0xdc/0x110 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 __wait_on_buffer+0x64/0x70 fs/buffer.c:123
 wait_on_buffer include/linux/buffer_head.h:420 [inline]
 jbd2_journal_commit_transaction+0x388a/0x6870 fs/jbd2/commit.c:837
 kjournald2+0x200/0x760 fs/jbd2/journal.c:201
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz-executor:5832 blocked in I/O wait for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22688 pid:5832  tgid:5832  ppid:5831   task_flags:0x440100 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 io_schedule+0x8a/0xf0 kernel/sched/core.c:8109
 bit_wait_io+0xd/0xe0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0x65/0x180 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0xdc/0x110 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 do_get_write_access+0x84f/0x1220 fs/jbd2/transaction.c:1113
 jbd2_journal_get_write_access+0x1d6/0x280 fs/jbd2/transaction.c:1263
 __ext4_journal_get_write_access+0x6a/0x340 fs/ext4/ext4_jbd2.c:241
 ext4_reserve_inode_write+0x1b7/0x330 fs/ext4/inode.c:6375
 __ext4_mark_inode_dirty+0x18f/0x890 fs/ext4/inode.c:6550
 ext4_dirty_inode+0xd9/0x130 fs/ext4/inode.c:6587
 __mark_inode_dirty+0x1f3/0x1720 fs/fs-writeback.c:2623
 generic_update_time fs/inode.c:2192 [inline]
 file_update_time_flags+0x46b/0x500 fs/inode.c:2422
 ext4_page_mkwrite+0x324/0x1890 fs/ext4/inode.c:6753
 do_page_mkwrite+0x17a/0x440 mm/memory.c:3668
 wp_page_shared mm/memory.c:4069 [inline]
 do_wp_page+0xa77/0x4350 mm/memory.c:4288
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault+0x1ab6/0x2a00 mm/memory.c:6549
 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
 do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7fa035d6eec0
RSP: 002b:00007ffc588679c8 EFLAGS: 00010246
RAX: 00007fa02f7e2ffc RBX: 00007ffc58867b70 RCX: 0000000000000000
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 00007fa02f7e2ffc
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000000
R10: 00007fa02f40021c R11: 000000000000000e R12: 000000000001cff4
R13: 000000000001cfda R14: 0000000000000010 R15: 00007ffc58867b70
 </TASK>
INFO: task syz.0.297:7190 blocked in I/O wait for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.297       state:D stack:27128 pid:7190  tgid:7190  ppid:5849   task_flags:0x440040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 io_schedule+0x8a/0xf0 kernel/sched/core.c:8109
 bit_wait_io+0xd/0xe0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0x65/0x180 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0xdc/0x110 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 do_get_write_access+0x84f/0x1220 fs/jbd2/transaction.c:1113
 jbd2_journal_get_write_access+0x1d6/0x280 fs/jbd2/transaction.c:1263
 __ext4_journal_get_write_access+0x6a/0x340 fs/ext4/ext4_jbd2.c:241
 ext4_reserve_inode_write+0x1b7/0x330 fs/ext4/inode.c:6375
 __ext4_mark_inode_dirty+0x18f/0x890 fs/ext4/inode.c:6550
 ext4_dirty_inode+0xd9/0x130 fs/ext4/inode.c:6587
 __mark_inode_dirty+0x1f3/0x1720 fs/fs-writeback.c:2623
 generic_update_time fs/inode.c:2192 [inline]
 file_update_time_flags+0x46b/0x500 fs/inode.c:2422
 ext4_page_mkwrite+0x324/0x1890 fs/ext4/inode.c:6753
 do_page_mkwrite+0x17a/0x440 mm/memory.c:3668
 do_shared_fault mm/memory.c:5969 [inline]
 do_fault+0x3b5/0x1750 mm/memory.c:6031
 do_pte_missing mm/memory.c:4550 [inline]
 handle_pte_fault mm/memory.c:6411 [inline]
 __handle_mm_fault+0x187d/0x2a00 mm/memory.c:6549
 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
 do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f4957e70f40
RSP: 002b:00007fffdf4618d0 EFLAGS: 00010202
RAX: 0000001b31ef5000 RBX: ffffffff82568f11 RCX: 0000001b31ef4ff8
RDX: 0000001b31b24220 RSI: 0000000000000008 RDI: 00007f4958d45720
RBP: 00000000000001a6 R08: 00007f4958200000 R09: 00007f4958202000
R10: 0000000082568f15 R11: 0000000000000010 R12: 00007f4958216038
R13: 00000000000002e8 R14: ffffffff825688e4 R15: 00007f4958d45720
 </TASK>
INFO: task syz.1.299:7195 blocked in I/O wait for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.299       state:D stack:27384 pid:7195  tgid:7195  ppid:5843   task_flags:0x440040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 io_schedule+0x8a/0xf0 kernel/sched/core.c:8109
 bit_wait_io+0xd/0xe0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0x65/0x180 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0xdc/0x110 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 do_get_write_access+0x84f/0x1220 fs/jbd2/transaction.c:1113
 jbd2_journal_get_write_access+0x1d6/0x280 fs/jbd2/transaction.c:1263
 __ext4_journal_get_write_access+0x6a/0x340 fs/ext4/ext4_jbd2.c:241
 ext4_reserve_inode_write+0x1b7/0x330 fs/ext4/inode.c:6375
 __ext4_mark_inode_dirty+0x18f/0x890 fs/ext4/inode.c:6550
 ext4_dirty_inode+0xd9/0x130 fs/ext4/inode.c:6587
 __mark_inode_dirty+0x1f3/0x1720 fs/fs-writeback.c:2623
 generic_update_time fs/inode.c:2192 [inline]
 touch_atime+0x642/0x7a0 fs/inode.c:2267
 file_accessed include/linux/fs.h:2264 [inline]
 ext4_file_mmap_prepare+0x56d/0x670 fs/ext4/file.c:840
 vfs_mmap_prepare include/linux/fs.h:2076 [inline]
 call_mmap_prepare mm/vma.c:2672 [inline]
 __mmap_region+0xe98/0x2da0 mm/vma.c:2755
 mmap_region+0x527/0x620 mm/vma.c:2856
 do_mmap+0xc63/0x12f0 mm/mmap.c:560
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
 ksys_mmap_pgoff+0x3cb/0x610 mm/mmap.c:606
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8e3d39c582
RSP: 002b:00007fffab0ea828 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000001b31c64000 RCX: 00007f8e3d39c582
RDX: 0000000000000003 RSI: 00000000003c0000 RDI: 0000001b31c64000
RBP: 0000000000100001 R08: 0000000000000004 R09: 0000000000040000
R10: 0000000000100001 R11: 0000000000000206 R12: 0000000000000047
R13: 00000000000927c0 R14: 000000000002f9d5 R15: 00007fffab0eab00
 </TASK>
INFO: task syz.2.298:7196 blocked in I/O wait for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.298       state:D stack:27384 pid:7196  tgid:7196  ppid:5853   task_flags:0x440040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 io_schedule+0x8a/0xf0 kernel/sched/core.c:8109
 bit_wait_io+0xd/0xe0 kernel/sched/wait_bit.c:250
 __wait_on_bit+0x65/0x180 kernel/sched/wait_bit.c:52
 out_of_line_wait_on_bit+0xdc/0x110 kernel/sched/wait_bit.c:67
 wait_on_bit_io include/linux/wait_bit.h:105 [inline]
 do_get_write_access+0x84f/0x1220 fs/jbd2/transaction.c:1113
 jbd2_journal_get_write_access+0x1d6/0x280 fs/jbd2/transaction.c:1263
 __ext4_journal_get_write_access+0x6a/0x340 fs/ext4/ext4_jbd2.c:241
 ext4_reserve_inode_write+0x1b7/0x330 fs/ext4/inode.c:6375
 __ext4_mark_inode_dirty+0x18f/0x890 fs/ext4/inode.c:6550
 ext4_dirty_inode+0xd9/0x130 fs/ext4/inode.c:6587
 __mark_inode_dirty+0x1f3/0x1720 fs/fs-writeback.c:2623
 generic_update_time fs/inode.c:2192 [inline]
 touch_atime+0x642/0x7a0 fs/inode.c:2267
 file_accessed include/linux/fs.h:2264 [inline]
 ext4_file_mmap_prepare+0x56d/0x670 fs/ext4/file.c:840
 vfs_mmap_prepare include/linux/fs.h:2076 [inline]
 call_mmap_prepare mm/vma.c:2672 [inline]
 __mmap_region+0xe98/0x2da0 mm/vma.c:2755
 mmap_region+0x527/0x620 mm/vma.c:2856
 do_mmap+0xc63/0x12f0 mm/mmap.c:560
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
 ksys_mmap_pgoff+0x3cb/0x610 mm/mmap.c:606
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6eda39c582
RSP: 002b:00007ffc7d052448 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000001b31d64000 RCX: 00007f6eda39c582
RDX: 0000000000000003 RSI: 00000000003c0000 RDI: 0000001b31d64000
RBP: 0000000000100001 R08: 0000000000000004 R09: 0000000000040000
R10: 0000000000100001 R11: 0000000000000206 R12: 0000000000000048
R13: 00000000000927c0 R14: 000000000002fd0a R15: 00007ffc7d052720
 </TASK>

Showing all locks held in the system:
6 locks held by kworker/u8:1/13:
 #0: ffff888020e8a940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
 #1: ffffc90000127d08 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
 #2: ffff88803313a0d8 (&type->s_umount_key#33){++++}-{4:4}, at: super_trylock_shared+0x1e/0xf0 fs/super.c:565
 #3: ffff888033138c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: do_writepages+0x278/0x600 mm/page-writeback.c:2575
 #4: ffff8880330b6938 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0xfaa/0x13a0 fs/jbd2/transaction.c:444
 #5: ffff88807a935fd0 (&ei->i_data_sem){++++}-{4:4}, at: ext4_map_blocks+0x45a/0xd30 fs/ext4/inode.c:823
1 lock held by khungtaskd/31:
 #0: ffffffff8e7e5260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e7e5260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e7e5260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/5602:
 #0: ffff888038d560a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14f0 drivers/tty/n_tty.c:2211
3 locks held by syz-executor/5832:
 #0: ffff888037e99448 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11d/0x590 mm/mmap_lock.c:310
 #1: ffff88803313a508 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x17a/0x440 mm/memory.c:3668
 #2: ffff8880330b6938 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0xfaa/0x13a0 fs/jbd2/transaction.c:444
3 locks held by syz.0.297/7190:
 #0: ffff8880565b7948 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x11d/0x590 mm/mmap_lock.c:310
 #1: ffff88803313a508 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x17a/0x440 mm/memory.c:3668
 #2: ffff8880330b6938 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0xfaa/0x13a0 fs/jbd2/transaction.c:444
3 locks held by syz.1.299/7195:
 #0: ffff888028438f78 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline]
 #0: ffff888028438f78 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1f5/0x470 mm/util.c:579
 #1: ffff88803313a410 (sb_writers#4){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2264 [inline]
 #1: ffff88803313a410 (sb_writers#4){.+.+}-{0:0}, at: ext4_file_mmap_prepare+0x56d/0x670 fs/ext4/file.c:840
 #2: ffff8880330b6938 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0xfaa/0x13a0 fs/jbd2/transaction.c:444
3 locks held by syz.2.298/7196:
 #0: ffff888028438338 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline]
 #0: ffff888028438338 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1f5/0x470 mm/util.c:579
 #1: ffff88803313a410 (sb_writers#4){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2264 [inline]
 #1: ffff88803313a410 (sb_writers#4){.+.+}-{0:0}, at: ext4_file_mmap_prepare+0x56d/0x670 fs/ext4/file.c:840
 #2: ffff8880330b6938 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0xfaa/0x13a0 fs/jbd2/transaction.c:444

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xcb1/0x1030 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/24 12:00 upstream dd6c438c3e64 629ff21a .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task jbd2/sda1-NUM:NUM blocked in I/O wait for more than NUM seconds.
2026/04/20 13:10 bpf-next 31f61ac33032 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce INFO: task jbd2/sda1-NUM:NUM blocked in I/O wait for more than NUM seconds.
2026/04/24 11:56 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing 2e6803928193 1c2b9291 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task jbd2/sda1-NUM:NUM blocked in I/O wait for more than NUM seconds.
* Struck through repros no longer work on HEAD.