syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7829/1:b..l
	(detected by 0, t=10502 jiffies, g=33645, q=201)
task:syz.1.1104      state:R  running task     stack:24352 pid: 7829 ppid:  6242 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:xas_find+0x7a/0xaa0 lib/xarray.c:1240
Code: de e8 2a 24 50 fd 48 83 fb 02 0f 94 c0 48 81 fd 06 c0 ff ff 0f 93 c3 20 c3 48 be fc ff ff ff 03 00 00 00 48 21 ee 41 0f 95 c6 <31> ff e8 ff 23 50 fd 44 84 f3 75 60 48 83 fd 01 74 5a 4c 89 64 24
RSP: 0018:ffffc900030f7708 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880502a1dc0
RDX: ffffc9000389c000 RSI: 00000000730d9e40 RDI: 0000000000000002
RBP: ffff8880730d9e40 R08: ffffffff84303dc6 R09: fffff940002f0c69
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc900030f7820
R13: ffffc900030f7838 R14: 0000000000000101 R15: 1ffff9200061ef07
 find_get_entry mm/filemap.c:1978 [inline]
 find_lock_entries+0x22a/0x1030 mm/filemap.c:2092
 shmem_undo_range+0x2a3/0x1b50 mm/shmem.c:943
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x21b/0xa00 mm/shmem.c:1145
 evict+0x2a4/0x620 fs/inode.c:587
 __dentry_kill+0x436/0x650 fs/dcache.c:586
 dentry_kill+0xbb/0x290
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x636/0x8e0 fs/file_table.c:288
 task_work_run+0x129/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1fc2437e9b
RSP: 002b:00007f1fc08b6e20 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: ffffffffffffffff RCX: 00007f1fc2437e9b
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000040
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000016
R13: 00007f1fc08b6ec0 R14: 000000000001f1d2 R15: 000000002003e3c0
 </TASK>
rcu: rcu_preempt kthread starved for 9880 jiffies! g33645 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:27064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 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 acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:570