INFO: task syz.2.3522:17945 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.3522      state:D stack:25000 pid:17945 tgid:17944 ppid:15149  task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 sync_bdevs+0x1ac/0x340 block/bdev.c:1288
 ksys_sync+0xb9/0x150 fs/sync.c:105
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc25a18ebe9
RSP: 002b:00007fc25af85038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fc25a3b5fa0 RCX: 00007fc25a18ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc25a3b5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc25a3b6038 R14: 00007fc25a3b5fa0 R15: 00007fff1b679598
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf60/0xfa0 kernel/hung_task.c:495
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 19654 Comm: syz.1.3908 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__list_del_entry_valid_or_report+0x9b/0x190 lib/list_debug.c:65
Code: c4 22 4d 39 e7 0f 84 94 00 00 00 4d 89 fc 49 c1 ec 03 43 80 3c 2c 00 74 08 4c 89 ff e8 ae f9 48 fd 49 39 1f 0f 85 92 00 00 00 <4d> 8d 7e 08 4d 89 fc 49 c1 ec 03 43 80 3c 2c 00 74 08 4c 89 ff e8
RSP: 0018:ffffc9000402f758 EFLAGS: 00000046
RAX: 1ffffd40002385a1 RBX: ffffea00011c2d08 RCX: 0000000000000000
RDX: 0000000000000017 RSI: 00000000000470b4 RDI: ffffea00011c2d10
RBP: ffffea00011c2d08 R08: ffffffff8fe50637 R09: 1ffffffff1fca0c6
R10: dffffc0000000000 R11: fffffbfff1fca0c7 R12: 1ffffd40002385a9
R13: dffffc0000000000 R14: ffff8880b863fd60 R15: ffffea00011c2d48
FS:  0000000000000000(0000) GS:ffff8881257cc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555c5698950 CR3: 000000000e336000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __list_del_entry_valid include/linux/list.h:124 [inline]
 __list_del_entry include/linux/list.h:215 [inline]
 list_del include/linux/list.h:229 [inline]
 free_pcppages_bulk+0x1b9/0x4e0 mm/page_alloc.c:1484
 free_frozen_page_commit+0x62c/0x1070 mm/page_alloc.c:2869
 __free_frozen_pages+0x67f/0xd30 mm/page_alloc.c:2923
 vfree+0x25a/0x400 mm/vmalloc.c:3434
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:535
 __fput+0x44c/0xa70 fs/file_table.c:468
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x1286/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5ebe9c14a5
Code: Unable to access opcode bytes at 0x7f5ebe9c147b.
RSP: 002b:00007f5ebf7f0f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007f5ebebb5fa0 RCX: 00007f5ebe9c14a5
RDX: 00007f5ebf7f0fc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f5ebea11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f5ebebb6038 R14: 00007f5ebebb5fa0 R15: 00007fff9af517c8
 </TASK>
vkms_vblank_simulate: vblank timer overrun