syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P23334/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=145277, q=392 ncpus=2)
task:syz-executor    state:R  running task     stack:26784 pid:23334 tgid:23334 ppid:14404  flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7067
 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:5758
Code: 2b 00 74 08 4c 89 f7 e8 0a 84 89 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:ffffc90003357be0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff9200066af88 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffffffff8bcaccc0 RDI: ffffffff8c202880
RBP: ffffc90003357d30 R08: ffffffff92fad587 R09: 1ffffffff25f5ab0
R10: dffffc0000000000 R11: fffffbfff25f5ab1 R12: 1ffff9200066af84
R13: dffffc0000000000 R14: ffffc90003357c40 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 rcu_read_lock include/linux/rcupdate.h:781 [inline]
 dput+0x54/0x2b0 fs/dcache.c:842
 path_put+0x39/0x60 fs/namei.c:561
 set_fs_pwd+0x1d0/0x290 fs/fs_struct.c:47
 __do_sys_chdir fs/open.c:566 [inline]
 __se_sys_chdir+0x1ce/0x220 fs/open.c:552
 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: 0033:0x7f8aa35749f7
RSP: 002b:00007ffcaa2f9b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000050
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8aa35749f7
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00007ffcaa2f9c20
RBP: 0000000000000001 R08: 0000000000000000 R09: 00007f8aa423d6c0
R10: 0000555577289500 R11: 0000000000000246 R12: 00007ffcaa2f9c60
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffcaa2f9c60
 </TASK>
rcu: rcu_preempt kthread starved for 10405 jiffies! g145277 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:26448 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5408 [inline]
 __schedule+0x17e8/0x4a20 kernel/sched/core.c:6745
 __schedule_loop kernel/sched/core.c:6822 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6837
 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2000
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2202
 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:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:111