syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9744/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=40737, q=272 ncpus=2)
task:syz.1.1339      state:R  running task     stack:26816 pid:9744  tgid:9743  ppid:5097   flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0x1800/0x4a60 kernel/sched/core.c:6529
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:6851
 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:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5763
Code: 2b 00 74 08 4c 89 f7 e8 1a 0e 8b 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc9000310fb00 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000621f6c RCX: 91e2de62539e0f00
RDX: dffffc0000000000 RSI: ffffffff8bcae720 RDI: ffffffff8c206820
RBP: ffffc9000310fc48 R08: ffffffff92ffd807 R09: 1ffffffff25ffb00
R10: dffffc0000000000 R11: fffffbfff25ffb01 R12: 1ffff92000621f68
R13: dffffc0000000000 R14: ffffc9000310fb60 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:326 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 __fget_files+0x49/0x470 fs/file.c:1035
 __fget_light fs/file.c:1151 [inline]
 __fdget+0x16c/0x1e0 fs/file.c:1159
 fdget include/linux/file.h:66 [inline]
 __do_sys_flock fs/locks.c:2155 [inline]
 __se_sys_flock+0x113/0x6c0 fs/locks.c:2131
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6f34d75f19
RSP: 002b:00007f6f35a6c048 EFLAGS: 00000246 ORIG_RAX: 0000000000000049
RAX: ffffffffffffffda RBX: 00007f6f34f05f60 RCX: 00007f6f34d75f19
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 000000000000000a
RBP: 00007f6f34de4e68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f6f34f05f60 R15: 00007ffd18a6bb08
 </TASK>
rcu: rcu_preempt kthread starved for 10233 jiffies! g40737 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:25168 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0x1800/0x4a60 kernel/sched/core.c:6529
 __schedule_loop kernel/sched/core.c:6606 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6621
 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+0x2f2/0x390 kernel/kthread.c:389
 ret_from_fork+0x4d/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:106 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111