syzbot

INFO: task syz-executor735:1295 blocked for more than 122 seconds.
      Not tainted 6.12.38-syzkaller-g3f3a5c5e782d #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor735 state:D stack:0     pid:1295  tgid:1295  ppid:298    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 io_schedule+0x89/0xe0 kernel/sched/core.c:8699
 folio_wait_bit_common+0x6ae/0x910 mm/filemap.c:1336
 folio_wait_bit+0x29/0x50 mm/filemap.c:1475
 folio_wait_writeback+0x90/0x1c0 mm/page-writeback.c:3195
 __filemap_fdatawait_range+0x148/0x210 mm/filemap.c:559
 file_write_and_wait_range+0x17f/0x1f0 mm/filemap.c:818
 v9fs_file_fsync+0xed/0x1d0 fs/9p/vfs_file.c:418
 vfs_fsync_range+0x17d/0x3a0 fs/sync.c:194
 generic_write_sync include/linux/fs.h:2888 [inline]
 netfs_file_write_iter+0x3b7/0x440 fs/netfs/buffered_write.c:489
 v9fs_file_write_iter+0xac/0xe0 fs/9p/vfs_file.c:407
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x697/0xe80 fs/read_write.c:684
 ksys_write+0x141/0x250 fs/read_write.c:737
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x7f/0x90 fs/read_write.c:746
 x64_sys_call+0x271c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f3651a9a519
RSP: 002b:00007ffec7f15008 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000140 RCX: 00007f3651a9a519
RDX: 0000000000007fec RSI: 0000200000000300 RDI: 0000000000000007
RBP: 0030656c69662f2e R08: 0000000000000003 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000246 R12: 0000200000000180
R13: 00007f3651ae3059 R14: 00007ffec7f15040 R15: 00000000000000f2
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted 6.12.38-syzkaller-g3f3a5c5e782d #0 c9247809a66a5ebb3467d1c2e99b1dedbd707993
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x10c/0x190 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2bf/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xd8f/0xed0 kernel/hung_task.c:423
 kthread+0x2ca/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 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 6.12.38-syzkaller-g3f3a5c5e782d #0 c9247809a66a5ebb3467d1c2e99b1dedbd707993
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x17/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc b8 95 c9 a2 50 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 83 91 3b 00 f3 0f 1e fa 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff87207da0 EFLAGS: 000002c6
RAX: ffff8881f6e00000 RBX: ffffffff87215540 RCX: ffffffff858bc09e
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000021d2d4
RBP: ffffffff87207da0 R08: ffff8881f6e39733 R09: 1ffff1103edc72e6
R10: dffffc0000000000 R11: ffffed103edc72e7 R12: 1ffffffff0e42aa8
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87cad828
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555555f496f8 CR3: 0000000102fe6000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:112 [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+0x3f/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1a0/0x470 kernel/sched/idle.c:326
 cpu_startup_entry+0x48/0x70 kernel/sched/idle.c:424
 rest_init+0x10b/0x130 init/main.c:748
 start_kernel+0x46a/0x4bb init/main.c:1135
 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>