syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P15940/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=116325, q=641 ncpus=2)
task:syz.3.2579      state:R  running task     stack:25568 pid:15940 tgid:15924 ppid:15474  flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5239 [inline]
 __schedule+0x1800/0x4a60 kernel/sched/core.c:6603
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:6925
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:kasan_mem_to_shadow include/linux/kasan.h:61 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x37/0x290 mm/kasan/generic.c:189
Code: 01 48 85 f6 0f 84 a0 01 00 00 4c 8d 04 37 49 39 f8 0f 82 56 02 00 00 48 89 fd 48 c1 ed 2f 81 fd fe ff 01 00 0f 86 43 02 00 00 <48> 89 fb 48 c1 eb 03 49 ba 00 00 00 00 00 fc ff df 4e 8d 1c 13 49
RSP: 0018:ffffc900043c71d0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff816fd680
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8fafdca8
RBP: 000000000001ffff R08: ffffffff8fafdcb0 R09: 1ffffffff2602100
R10: dffffc0000000000 R11: fffffbfff2602101 R12: 1ffff92000878e4c
R13: ffffffff820412c9 R14: ffffffff820412c9 R15: dffffc0000000000
 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:562 [inline]
 cpu_online include/linux/cpumask.h:1113 [inline]
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0xb0/0xa30 kernel/locking/lockdep.c:5833
 rcu_lock_release include/linux/rcupdate.h:336 [inline]
 rcu_read_unlock include/linux/rcupdate.h:869 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:337 [inline]
 percpu_ref_put+0xfa/0x180 include/linux/percpu-refcount.h:351
 obj_cgroup_put include/linux/memcontrol.h:802 [inline]
 __memcg_slab_free_hook+0xa7/0x310 mm/memcontrol.c:3050
 memcg_slab_free_hook mm/slub.c:2186 [inline]
 slab_free mm/slub.c:4470 [inline]
 kmem_cache_free+0x1cf/0x350 mm/slub.c:4548
 anon_vma_chain_free mm/rmap.c:147 [inline]
 unlink_anon_vmas+0x297/0x5f0 mm/rmap.c:421
 free_pgtables+0x567/0x840 mm/memory.c:409
 exit_mmap+0x447/0xc80 mm/mmap.c:3423
 __mmput+0x115/0x390 kernel/fork.c:1347
 vhost_detach_mm drivers/vhost/vhost.c:614 [inline]
 vhost_dev_cleanup+0xa78/0xba0 drivers/vhost/vhost.c:1052
 vhost_vsock_dev_release+0x3ac/0x410 drivers/vhost/vsock.c:752
 __fput+0x24a/0x8a0 fs/file_table.c:422
 task_work_run+0x24f/0x310 kernel/task_work.c:222
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2f/0x27f0 kernel/exit.c:882
 do_group_exit+0x207/0x2c0 kernel/exit.c:1031
 get_signal+0x16a1/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x830 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [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+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fadce175b59
RSP: 002b:00007fadcefa0048 EFLAGS: 00000246 ORIG_RAX: 00000000000001ae
RAX: 0000000000000009 RBX: 00007fadce306038 RCX: 00007fadce175b59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000280
RBP: 00007fadce1e4e5d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fadce306038 R15: 00007fffc267c208
 </TASK>
rcu: rcu_preempt kthread starved for 10425 jiffies! g116325 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:25904 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5239 [inline]
 __schedule+0x1800/0x4a60 kernel/sched/core.c:6603
 __schedule_loop kernel/sched/core.c:6680 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6695
 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2034
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2236
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:144
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111