syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5852/1:b..l
	(detected by 0, t=10502 jiffies, g=17493, q=508)
task:syz.0.404       state:R  running task     stack:23376 pid: 5852 ppid:  4190 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90003367120 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 75efaf513f895d00
RDX: 0000000000000000 RSI: ffffffff8a2b3aa0 RDI: ffffffff8a79fe00
RBP: ffffc90003367238 R08: dffffc0000000000 R09: 1ffffffff203aa18
R10: dffffc0000000000 R11: fffffbfff203aa19 R12: ffffffff8c31eb20
R13: 1ffff9200066ce30 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:317 [inline]
 percpu_ref_put+0x16/0x150 include/linux/percpu-refcount.h:338
 __mem_cgroup_uncharge_list+0x6c/0xc0 mm/memcontrol.c:7004
 mem_cgroup_uncharge_list include/linux/memcontrol.h:720 [inline]
 release_pages+0x1864/0x1be0 mm/swap.c:962
 __pagevec_release+0x6d/0xe0 mm/swap.c:983
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x62b/0x1930 mm/shmem.c:964
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x220/0xa40 mm/shmem.c:1145
 evict+0x4c9/0x8d0 fs/inode.c:647
 __dentry_kill+0x431/0x650 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5ee/0x930 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x626/0x20c0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:320
 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1499
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0033:0x7fd21fd43de1
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fd21ffbd090 RCX: 00007fd21fd43dd9
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007fd21fdd9d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fd21ffbd128 R14: 00007fd21ffbd090 R15: 00007ffc6efdd628
 </TASK>
rcu: rcu_preempt kthread starved for 9902 jiffies! g17493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:26960 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:729