INFO: task kworker/u8:1:13 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1    state:D stack:0     pid:13    tgid:13    ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6063 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7883
 __schedule_loop kernel/sched/core.c:7960 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7975
 io_schedule+0x85/0x150 kernel/sched/core.c:8790
 bit_wait_io+0x17/0xd0 kernel/sched/wait_bit.c:209
 __wait_on_bit_lock+0x23e/0x5e0 kernel/sched/wait_bit.c:90
 out_of_line_wait_on_bit_lock+0x139/0x190 kernel/sched/wait_bit.c:117
 wait_on_bit_lock_io include/linux/wait_bit.h:208 [inline]
 __lock_buffer+0x5d/0x70 fs/buffer.c:71
 lock_buffer include/linux/buffer_head.h:434 [inline]
 do_get_write_access+0x196/0xd70 fs/jbd2/transaction.c:972
 jbd2_journal_get_write_access+0x268/0x3d0 fs/jbd2/transaction.c:1245
 __ext4_journal_get_write_access+0x1b6/0x6a0 fs/ext4/ext4_jbd2.c:239
 ext4_mb_mark_context+0x1f3/0xee0 fs/ext4/mballoc.c:4094
 ext4_mb_mark_diskspace_used+0x3aa/0x830 fs/ext4/mballoc.c:4223
 ext4_mb_new_blocks+0x840/0x36c0 fs/ext4/mballoc.c:6318
 ext4_ext_map_blocks+0x14d9/0x6080 fs/ext4/extents.c:4437
 ext4_map_create_blocks fs/ext4/inode.c:520 [inline]
 ext4_map_blocks+0x873/0x17f0 fs/ext4/inode.c:706
 mpage_map_one_extent fs/ext4/inode.c:2222 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2275 [inline]
 ext4_do_writepages+0x1c4a/0x39f0 fs/ext4/inode.c:2738
 ext4_writepages+0x28c/0x550 fs/ext4/inode.c:2827
 do_writepages+0x3d7/0x7f0 mm/page-writeback.c:2690
 __writeback_single_inode+0xc8/0xba0 fs/fs-writeback.c:1674
 writeback_sb_inodes+0x6a5/0xfb0 fs/fs-writeback.c:1970
 __writeback_inodes_wb+0x129/0x280 fs/fs-writeback.c:2041
 wb_writeback+0x3bb/0x850 fs/fs-writeback.c:2152
 wb_check_background_flush fs/fs-writeback.c:2222 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0xab0/0xef0 fs/fs-writeback.c:2337
 process_one_work kernel/workqueue.c:3273 [inline]
 process_scheduled_works+0x7f4/0x1060 kernel/workqueue.c:3354
 worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435
 kthread+0x2c4/0x360 kernel/kthread.c:389
 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 e67cc5743245539115c479145c763e2a95730d6f
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:114
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:63
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 cpumask_backtrace+0x1f/0x30 lib/nmi_backtrace.c:127
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c4/0x360 kernel/kthread.c:389
 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 e67cc5743245539115c479145c763e2a95730d6f
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:116
Code: cc cc cc cc cc cc cc b8 5b 3e 82 b2 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d c3 07 42 00 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90
RSP: 0018:ffffffff87407da0 EFLAGS: 000002c2
RAX: ffff8881f6e00000 RBX: ffffffff874156c0 RCX: ffffffff85a5553d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000017298c
RBP: ffffffff87407da0 R08: ffff8881f6e395eb R09: 1ffff1103edc72bd
R10: dffffc0000000000 R11: ffffed103edc72be R12: 0000000000000000
R13: 1ffffffff0e82ad8 R14: dffffc0000000000 R15: ffffffff87ece328
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555559cbb828 CR3: 0000000131872000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:-1 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3e/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:193 [inline]
 do_idle+0x2fc/0x570 kernel/sched/idle.c:346
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:445
 rest_init+0x10b/0x130 init/main.c:760
 start_kernel+0x462/0x4bb init/main.c:1242
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x6a/0x7b arch/x86/kernel/head64.c:488
 common_startup_64+0x13b/0x157
 </TASK>