syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=39301, q=53)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295000419-4294989917), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.5  R  running task    27192 15564   9898 0x00000000
Call Trace:
 <IRQ>
 sched_show_task kernel/sched/core.c:5952 [inline]
 sched_show_task.cold+0x2ee/0x35d kernel/sched/core.c:5927
 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:558 [inline]
 rcu_pending kernel/rcu/tree.c:3226 [inline]
 rcu_sched_clock_irq.cold+0xb92/0xcc2 kernel/rcu/tree.c:2297
 update_process_times+0x2d/0x70 kernel/time/timer.c:1727
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:debug_lockdep_rcu_enabled.part.0+0x37/0x60 kernel/rcu/update.c:264
Code: e5 53 65 48 8b 1c 25 c0 1e 02 00 48 8d bb 9c 08 00 00 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 <84> d2 75 10 8b 93 9c 08 00 00 31 c0 5b 5d 85 d2 0f 94 c0 c3 e8 c0
RSP: 0018:ffffc90005477d10 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000007 RBX: ffff8880898101c0 RCX: 1ffffffff154c1da
RDX: 0000000000000000 RSI: ffffffff81c0d7b9 RDI: ffff888089810a5c
RBP: ffffc90005477d18 R08: ffff8880898101c0 R09: fffffbfff16a3d0b
R10: ffff888089810a60 R11: ffff8880898101c0 R12: ffff8880a993c358
R13: 0000000000000000 R14: 00000000000000e0 R15: ffff88809fa0fa20
 debug_lockdep_rcu_enabled kernel/rcu/update.c:263 [inline]
 rcu_read_lock_held_common+0x7d/0x130 kernel/rcu/update.c:100
 rcu_read_lock_any_held+0x5b/0xf0 kernel/rcu/update.c:328
 rcu_sync_is_idle include/linux/rcu_sync.h:34 [inline]
 percpu_down_read include/linux/percpu-rwsem.h:62 [inline]
 __sb_start_write+0x3fe/0x4a0 fs/super.c:1674
 file_start_write include/linux/fs.h:2903 [inline]
 vfs_write+0x485/0x5d0 fs/read_write.c:557
 ksys_pwrite64+0x183/0x1c0 fs/read_write.c:665
 __do_sys_pwrite64 fs/read_write.c:675 [inline]
 __se_sys_pwrite64 fs/read_write.c:672 [inline]
 __x64_sys_pwrite64+0x97/0xf0 fs/read_write.c:672
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x416247
Code: 12 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a1 18 00 00 c3 48 83 ec 08 e8 a7 f9 ff ff 48 89 04 24 49 89 ca b8 12 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 ed f9 ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fe3ac9a3a60 EFLAGS: 00000293 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fe3ac9a46d4 RCX: 0000000000416247
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 000000000076c060 R08: fe03f80fe03f80ff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000bdc R14: 00000000004cdb9f R15: 000000000076c06c
rcu: rcu_preempt kthread starved for 10502 jiffies! g39301 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29232    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3380 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4080
 schedule+0xdc/0x2b0 kernel/sched/core.c:4154
 schedule_timeout+0x36e/0x8c0 kernel/time/timer.c:1898
 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline]
 rcu_gp_kthread+0xa02/0x1b00 kernel/rcu/tree.c:1837
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352