syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (1 GPs behind) idle=d16/1/0x4000000000000002 softirq=10616/10619 fqs=11 
	(t=10500 jiffies g=6841 q=482)
rcu: rcu_preempt kthread starved for 10477 jiffies! g6841 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29032    10      2 0x80004000
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081
 schedule+0x181/0x210 kernel/sched/core.c:4155
 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline]
 rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
NMI backtrace for cpu 0
CPU: 0 PID: 8377 Comm: syz-executor.0 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fb/0x318 lib/dump_stack.c:118
 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:529 [inline]
 rcu_pending kernel/rcu/tree.c:2827 [inline]
 rcu_sched_clock_irq+0xe25/0x1ad0 kernel/rcu/tree.c:2271
 update_process_times+0x12d/0x180 kernel/time/timer.c:1726
 tick_sched_handle kernel/time/tick-sched.c:167 [inline]
 tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:__memcg_kmem_uncharge+0x38/0x2e0 mm/memcontrol.c:2910
Code: 89 f3 49 89 fc 48 b8 00 00 00 00 00 fc ff df 4c 8d 77 38 4d 89 f5 49 c1 ed 03 41 80 7c 05 00 00 74 08 4c 89 f7 e8 d8 f4 fa ff <4d> 8b 3e b8 01 00 00 00 89 d9 d3 e0 4d 85 ff 0f 84 bf 01 00 00 4c
RSP: 0018:ffffc900025978b8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff8880a81c6040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea00029e8980
RBP: ffffc900025978e8 R08: dffffc0000000000 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: ffffea00029e8980
R13: 1ffffd400053d137 R14: ffffea00029e89b8 R15: ffff8880a7e994e8
 memcg_kmem_uncharge include/linux/memcontrol.h:1402 [inline]
 free_thread_stack+0x12e/0x590 kernel/fork.c:284
 release_task_stack kernel/fork.c:440 [inline]
 put_task_stack+0xa3/0x130 kernel/fork.c:451
 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256
 context_switch kernel/sched/core.c:3388 [inline]
 __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081
 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338
 retint_kernel+0x1b/0x2b
RIP: 0010:browse_rb mm/mmap.c:344 [inline]
RIP: 0010:validate_mm+0x2cd/0x9b0 mm/mmap.c:426
Code: e8 d8 94 d1 ff 44 89 f0 48 89 45 98 48 89 5d c8 4c 8d 7b e0 4d 89 fe 49 c1 ee 03 48 b8 00 00 00 00 00 fc ff df 41 80 3c 06 00 <74> 08 4c 89 ff e8 a9 0b 0d 00 49 8b 1f 48 89 df 4c 89 ee e8 9b 96
RSP: 0018:ffffc90002597b40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff8880a2777a70 RCX: ffff8880a81c6040
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880a2777b78
RBP: ffffc90002597bd8 R08: dffffc0000000000 R09: ffffed1011796170
R10: ffffed1011796170 R11: 0000000000000000 R12: 00007fbc4eb69000
R13: 00007fbc4e969000 R14: 1ffff110144eef4a R15: ffff8880a2777a50
 vma_link+0x264/0x290 mm/mmap.c:666
 mmap_region+0x12e1/0x1cb0 mm/mmap.c:1807
 do_mmap+0xabb/0x1120 mm/mmap.c:1555
 do_mmap_pgoff include/linux/mm.h:2338 [inline]
 vm_mmap_pgoff+0x13d/0x1d0 mm/util.c:506
 ksys_mmap_pgoff+0x104/0x560 mm/mmap.c:1607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x103/0x120 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a6ca
Code: 89 f5 41 54 49 89 fc 55 53 74 35 49 63 e8 48 63 da 4d 89 f9 49 89 e8 4d 63 d6 48 89 da 4c 89 ee 4c 89 e7 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4e 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 00
RSP: 002b:00007ffef200a648 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6ca
RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000
RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000