syzbot

INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 0, t=10502 jiffies, g=14946, c=14945, q=84)
All QSes seen, last rcu_preempt kthread activity 10503 (4294984947-4294974444), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.3  R  running task    27016 22141   6376 0x8000000c
Call Trace:
 <IRQ>
 sched_show_task.cold+0x333/0x39a kernel/sched/core.c:5169
 print_other_cpu_stall kernel/rcu/tree.c:1501 [inline]
 check_cpu_stall kernel/rcu/tree.c:1616 [inline]
 __rcu_pending kernel/rcu/tree.c:3390 [inline]
 rcu_pending kernel/rcu/tree.c:3452 [inline]
 rcu_check_callbacks.cold+0xd29/0xd99 kernel/rcu/tree.c:2792
 update_process_times+0x28/0xa0 kernel/time/timer.c:1591
 tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165
 tick_sched_timer+0x92/0x200 kernel/time/tick-sched.c:1223
 __run_hrtimer kernel/time/hrtimer.c:1223 [inline]
 __hrtimer_run_queues+0x30b/0xc80 kernel/time/hrtimer.c:1287
 hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
 smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100
 apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:793
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:kmem_cache_free+0x173/0x2b0 mm/slab.c:3759
RSP: 0018:ffff8880aea07d50 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000007 RBX: ffff8880a99c4e00 RCX: 1ffff1100d036db5
RDX: 0000000000000000 RSI: ffff8880681b6db0 RDI: 0000000000000286
RBP: ffff8880a9a74c00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000286
R13: ffffffff850e7ce8 R14: ffff888084b232c0 R15: ffff888084b21a68
 kfree_skbmem+0x98/0x100 net/core/skbuff.c:586
 __kfree_skb net/core/skbuff.c:646 [inline]
 consume_skb+0xed/0x380 net/core/skbuff.c:705
 mac80211_hwsim_tx_frame+0x116/0x1f0 drivers/net/wireless/mac80211_hwsim.c:1500
 mac80211_hwsim_beacon_tx+0x3a8/0x570 drivers/net/wireless/mac80211_hwsim.c:1538
 __iterate_interfaces+0x247/0x3c0 net/mac80211/util.c:613
 ieee80211_iterate_active_interfaces_atomic+0x74/0x130 net/mac80211/util.c:649
 mac80211_hwsim_beacon+0xbe/0x180 drivers/net/wireless/mac80211_hwsim.c:1558
 __tasklet_hrtimer_trampoline+0x29/0xa0 kernel/softirq.c:618
 tasklet_hi_action+0x195/0x330 kernel/softirq.c:549
 __do_softirq+0x254/0xa1d kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x193/0x240 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x141/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x93/0xa0 arch/x86/entry/entry_64.S:793
 </IRQ>
RIP: 0010:PageAnon include/linux/page-flags.h:407 [inline]
RIP: 0010:zap_pte_range mm/memory.c:1332 [inline]
RIP: 0010:zap_pmd_range mm/memory.c:1444 [inline]
RIP: 0010:zap_pud_range mm/memory.c:1473 [inline]
RIP: 0010:zap_p4d_range mm/memory.c:1494 [inline]
RIP: 0010:unmap_page_range+0xdec/0x1ce0 mm/memory.c:1515
RSP: 0018:ffff888061bdf7c0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: 1ffffd4000347881 RBX: dffffc0000000000 RCX: ffff888061bdf9d0
RDX: 0000000000000000 RSI: ffff888061bdf9d0 RDI: ffffea0001a3c408
RBP: ffff8880621223f8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8880681b6500 R12: ffffea0001a3c400
R13: ffffea0001a3c420 R14: 00007fca65280000 R15: ffffea0001a3c400
 unmap_single_vma+0x147/0x2b0 mm/memory.c:1560
 unmap_vmas+0x9d/0x160 mm/memory.c:1590
 exit_mmap+0x270/0x4d0 mm/mmap.c:3056
 __mmput kernel/fork.c:930 [inline]
 mmput kernel/fork.c:951 [inline]
 mmput+0xfa/0x420 kernel/fork.c:946
 exit_mm kernel/exit.c:545 [inline]
 do_exit+0x948/0x27f0 kernel/exit.c:852
 do_group_exit+0x100/0x2e0 kernel/exit.c:962
 get_signal+0x38d/0x1ca0 kernel/signal.c:2423
 do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45de59
RSP: 002b:00007fca6498ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: 0000000000000006 RBX: 0000000000024440 RCX: 000000000045de59
RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 000000000118bf68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffe2723cf9f R14: 00007fca6498b9c0 R15: 000000000118bf2c
rcu_preempt kthread starved for 10547 jiffies! g14946 c14945 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1
rcu_preempt     R  running task    30008     8      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x4af/0xe90 kernel/time/timer.c:1754
 rcu_gp_kthread+0xc0a/0x1e60 kernel/rcu/tree.c:2255
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404