syzbot

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-...!: (10499 ticks this GP) idle=e06/1/0x4000000000000002 softirq=10118/10118 fqs=1 
	(t=10500 jiffies g=6373 q=70)
rcu: rcu_preempt kthread starved for 10498 jiffies! g6373 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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 1
CPU: 1 PID: 8246 Comm: syz-executor.2 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+0x210/0x2e0 mm/memcontrol.c:2925
Code: e8 65 db a4 ff 48 c7 c7 98 4b 0d 89 e8 59 97 00 00 bf 01 00 00 00 e8 2f e3 9b ff 65 8b 05 d4 fd 4a 7e 85 c0 74 53 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 49 8d 5f 10 48 89 df be 08 00 00
RSP: 0018:ffffc90002027940 EFLAGS: 00000292 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0001b1bc00
RBP: ffffc90002027968 R08: dffffc0000000000 R09: fffffbfff120248a
R10: fffffbfff120248a R11: 0000000000000000 R12: ffffea0001b1bc00
R13: 1ffffd4000363787 R14: ffffea0001b1bc38 R15: 0000000000000000
 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:check_kcov_mode kernel/kcov.c:79 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:102
Code: 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 <83> fa 02 75 21 48 8b 91 88 13 00 00 48 8b 32 48 8d 7e 01 8b 89 84
RSP: 0018:ffffc90002027bc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff863b0037 RBX: ffff8880a7640000 RCX: ffff88809549e100
RDX: 0000000000000000 RSI: 0000000000000024 RDI: ffff8880a7640000
RBP: ffffc90002027be0 R08: ffffffff863af5f7 R09: ffffffff863b0020
R10: ffffed1015d86fcd R11: 0000000000000000 R12: ffff888092d40bc0
R13: ffff888092d40bc0 R14: ffffc90002027dc0 R15: 0000000000000024
 __skb_datagram_iter+0xe3/0x790 net/core/datagram.c:423
 skb_copy_datagram_iter+0x44/0x60 net/core/datagram.c:529
 skb_copy_datagram_msg include/linux/skbuff.h:3489 [inline]
 netlink_recvmsg+0x2d4/0xfb0 net/netlink/af_netlink.c:1975
 sock_recvmsg_nosec net/socket.c:873 [inline]
 sock_recvmsg net/socket.c:891 [inline]
 __sys_recvfrom+0x328/0x4b0 net/socket.c:2042
 __do_sys_recvfrom net/socket.c:2060 [inline]
 __se_sys_recvfrom net/socket.c:2056 [inline]
 __x64_sys_recvfrom+0xe5/0x100 net/socket.c:2056
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x41425d
Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 8b 05 1e 42 66 00 85 c0 75 3e 45 31 c9 45 31 c0 4c 63 d1 48 63 ff b8 2d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0b c3 66 2e 0f 1f 84 00 00 00 00 00 48 c7 c2
RSP: 002b:00007ffe06c11398 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 0000000000a72200 RCX: 000000000041425d
RDX: 0000000000000400 RSI: 0000000000a72250 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000a72250 R15: 0000000000000003