syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11571/1:b..l
rcu: 	(detected by 1, t=10504 jiffies, g=76689, q=557 ncpus=2)
task:syz.3.1624      state:R  running task     stack:28528 pid:11571 tgid:11571 ppid:11569  flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0xf15/0x5d00 kernel/sched/core.c:6745
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7067
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x1f2/0x560 kernel/locking/lockdep.c:5722
Code: c1 05 1a ad 96 7e 83 f8 01 0f 85 ea 02 00 00 9c 58 f6 c4 02 0f 85 d5 02 00 00 48 85 ed 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc90003d17a40 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff920007a2f4a RCX: 00000000e9444457
RDX: 0000000000000001 RSI: ffffffff8b2cb200 RDI: ffffffff8b8ff680
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff284ca58
R10: ffffffff942652c7 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8dbb1620 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 rcu_read_lock include/linux/rcupdate.h:781 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:330 [inline]
 percpu_ref_put include/linux/percpu-refcount.h:351 [inline]
 obj_cgroup_put include/linux/memcontrol.h:822 [inline]
 obj_cgroup_put include/linux/memcontrol.h:819 [inline]
 __memcg_slab_free_hook+0x2f6/0x5a0 mm/memcontrol.c:3804
 memcg_slab_free_hook mm/slub.c:2130 [inline]
 slab_free mm/slub.c:4435 [inline]
 kmem_cache_free+0x357/0x3a0 mm/slub.c:4513
 vma_lock_free kernel/fork.c:453 [inline]
 __vm_area_free+0xee/0x140 kernel/fork.c:509
 remove_vma+0x12b/0x180 mm/mmap.c:146
 exit_mmap+0x4d4/0xb20 mm/mmap.c:3365
 __mmput+0x12a/0x4d0 kernel/fork.c:1346
 mmput+0x62/0x70 kernel/fork.c:1368
 exit_mm kernel/exit.c:567 [inline]
 do_exit+0x9b7/0x2ba0 kernel/exit.c:863
 __do_sys_exit kernel/exit.c:992 [inline]
 __se_sys_exit kernel/exit.c:990 [inline]
 __x64_sys_exit+0x42/0x50 kernel/exit.c:990
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6389d75bd9
RSP: 002b:00007f638aa5fff8 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007f6389f04038 RCX: 00007f6389d75bd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f6389de4aa1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f6389f04038 R15: 00007fff6c7025f8
 </TASK>
rcu: rcu_preempt kthread starved for 10408 jiffies! g76689 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:28128 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0xf15/0x5d00 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6837
 schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2000
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2202
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 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:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:112