syzbot

INFO: task syz-executor:374 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:374   tgid:374   ppid:1      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
 netfs_wait_for_outstanding_io include/linux/netfs.h:542 [inline]
 v9fs_evict_inode+0x15b/0x2d0 fs/9p/vfs_inode.c:348
 evict+0x4d3/0xa90 fs/inode.c:730
 iput_final fs/inode.c:1889 [inline]
 iput+0x639/0x8d0 fs/inode.c:1915
 dentry_unlink_inode+0x373/0x420 fs/dcache.c:412
 __dentry_kill+0x1b4/0x5f0 fs/dcache.c:615
 dput+0x3f2/0x510 fs/dcache.c:857
 do_one_tree fs/dcache.c:1553 [inline]
 shrink_dcache_for_umount+0xce/0x1a0 fs/dcache.c:1567
 generic_shutdown_super+0x6a/0x300 fs/super.c:623
 kill_anon_super+0x4b/0x1d0 fs/super.c:1240
 v9fs_kill_super+0x50/0x90 fs/9p/vfs_super.c:193
 deactivate_locked_super+0xd5/0x2a0 fs/super.c:476
 deactivate_super+0xb8/0xe0 fs/super.c:509
 cleanup_mnt+0x3f1/0x480 fs/namespace.c:1370
 __cleanup_mnt+0x1d/0x40 fs/namespace.c:1377
 task_work_run+0x1e0/0x250 kernel/task_work.c:240
 resume_user_mode_work+0x36/0x50 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x64/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f9d551902f7
RSP: 002b:00007ffe7ef3e488 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9d55211d7d RCX: 00007f9d551902f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe7ef3e540
RBP: 00007ffe7ef3e540 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffe7ef3f5d0
R13: 00007f9d55211d7d R14: 0000000000035680 R15: 00007ffe7ef3f610
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 0b5ffdee5fcd2f7749818d1ff954e9c21353764e
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 0b5ffdee5fcd2f7749818d1ff954e9c21353764e
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__kasan_check_read+0x15/0x20 mm/kasan/shadow.c:31
Code: 45 31 ff eb c9 b8 68 de 6c 06 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 e5 89 f6 48 8b 4d 08 31 d2 e8 ab e4 ff ff <5d> e9 45 4c b3 03 cc 0f 1f 40 00 b8 68 de 6c 06 90 90 90 90 90 90
RSP: 0018:ffffc90000230c90 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 1ffff1102166f12b RCX: ffffffff815f0384
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff87cb2140
RBP: ffffc90000230c90 R08: ffffffff87cb2147 R09: 1ffffffff0f96428
R10: dffffc0000000000 R11: fffffbfff0f96429 R12: 0000000000000001
R13: ffff88810b378948 R14: ffff88810b378938 R15: 1ffff1102166f127
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555698494a8 CR3: 000000012136a000 CR4: 00000000003526b0
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:570 [inline]
 cpu_active include/linux/cpumask.h:1137 [inline]
 update_tg_load_avg kernel/sched/fair.c:4283 [inline]
 __update_blocked_fair kernel/sched/fair.c:10062 [inline]
 sched_balance_update_blocked_averages+0x7b4/0x1320 kernel/sched/fair.c:10167
 update_nohz_stats kernel/sched/fair.c:12864 [inline]
 _nohz_idle_balance+0x31e/0x5a0 kernel/sched/fair.c:12932
 nohz_idle_balance kernel/sched/fair.c:12989 [inline]
 sched_balance_softirq+0x8a/0x170 kernel/sched/fair.c:13224
 handle_softirqs+0x1ab/0x630 kernel/softirq.c:621
 __do_softirq kernel/softirq.c:659 [inline]
 invoke_softirq kernel/softirq.c:476 [inline]
 __irq_exit_rcu+0x48/0xc0 kernel/softirq.c:708
 irq_exit_rcu+0xd/0x30 kernel/softirq.c:720
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
 sysvec_call_function_single+0x7f/0x90 arch/x86/kernel/smp.c:266
 </IRQ>
 <TASK>
 asm_sysvec_call_function_single+0x1f/0x30 arch/x86/include/asm/idtentry.h:709
RIP: 0010:pv_native_safe_halt+0x17/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc b8 fd f5 ad 68 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d c3 e2 39 00 f3 0f 1e fa 55 48 89 e5 fb f4 <5d> e9 d3 54 02 00 cc cc cc b8 00 00 00 00 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900001a7e00 EFLAGS: 000002c2
RAX: ffff8881f6f00000 RBX: ffff88810366cc00 RCX: ffffffff858d70be
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000000abb4c
RBP: ffffc900001a7e00 R08: ffff8881f6f39733 R09: 1ffff1103ede72e6
R10: dffffc0000000000 R11: ffffed103ede72e7 R12: 1ffff110206cd980
R13: 0000000000000001 R14: 0000000000000000 R15: ffffffff87cb2128
 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
 start_secondary+0x12e/0x140 arch/x86/kernel/smpboot.c:314
 common_startup_64+0x13b/0x157
 </TASK>