syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=6533, q=434)
rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294954282-4294943779), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.0  R  running task    24072  8480   8479 0x0000400a
Call Trace:
 <IRQ>
 sched_show_task+0x40f/0x560 kernel/sched/core.c:5954
 print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:538 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0x1861/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__memcg_kmem_uncharge+0x8/0x1a0 mm/memcontrol.c:2908
Code: 07 00 74 12 48 81 c3 08 02 00 00 48 89 df 4c 89 f6 e8 8c 85 ff ff 5b 41 5e 5d c3 0f 1f 80 00 00 00 00 55 48 89 e5 41 57 41 56 <41> 55 41 54 53 50 89 f3 49 89 fc 48 b8 00 00 00 00 00 fc ff df 4c
RSP: 0018:ffffc90001ea7c40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff81489244 RBX: ffffea00024a5880 RCX: ffff88807d5be640
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00024a5880
RBP: ffffc90001ea7c50 R08: dffffc0000000000 R09: fffffbfff12c962d
R10: fffffbfff12c962d R11: 0000000000000000 R12: ffff88809e11fa20
R13: dffffc0000000000 R14: 1ffff11013c23f44 R15: ffff888090605478
 memcg_kmem_uncharge include/linux/memcontrol.h:1402 [inline]
 free_thread_stack+0x12e/0x590 kernel/fork.c:284
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_common kernel/sched/core.c:4236 [inline]
 preempt_schedule+0xdb/0x120 kernel/sched/core.c:4261
 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50
 __raw_read_unlock include/linux/rwlock_api_smp.h:227 [inline]
 _raw_read_unlock+0x3a/0x40 kernel/locking/spinlock.c:255
 kill_something_info kernel/signal.c:1586 [inline]
 __do_sys_kill kernel/signal.c:3640 [inline]
 __se_sys_kill+0x5e9/0x6c0 kernel/signal.c:3634
 __x64_sys_kill+0x5b/0x70 kernel/signal.c:3634
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4232e7
Code: 44 00 00 48 c7 c2 d4 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 b8 3e 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 dd 32 ff ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff2ac5f558 EFLAGS: 00000293 ORIG_RAX: 000000000000003e
RAX: ffffffffffffffda RBX: 0000000000000064 RCX: 00000000004232e7
RDX: 0000000000000bb8 RSI: 0000000000000009 RDI: 00000000fffffffe
RBP: 0000000000000002 R08: 0000000000000001 R09: 0000000001baa940
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000005
R13: 00007fff2ac5f590 R14: 00000000000102b2 R15: 00007fff2ac5f5a0
rcu: rcu_preempt kthread starved for 10532 jiffies! g6533 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29032    10      2 0x80004008
Call Trace:
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352