==================================================================
BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_sched_do_timer

write to 0xffffffff85d056d0 of 4 bytes by interrupt on cpu 0:
 tick_sched_do_timer+0xb4/0xd0 kernel/time/tick-sched.c:136
 tick_sched_timer+0x3f/0xd0 kernel/time/tick-sched.c:1307
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x271/0x600 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x226/0x490 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0xd8/0x270 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
 slab_alloc mm/slab.c:3313 [inline]
 kmem_cache_alloc+0xa9/0x5e0 mm/slab.c:3488
 skb_clone+0xf4/0x280 net/core/skbuff.c:1449
 dev_queue_xmit_nit+0x2b8/0x600 net/core/dev.c:2239
 xmit_one net/core/dev.c:3466 [inline]
 dev_hard_start_xmit+0x3ed/0x420 net/core/dev.c:3486
 sch_direct_xmit+0x2ae/0x8a0 net/sched/sch_generic.c:313
 __dev_xmit_skb net/core/dev.c:3671 [inline]
 __dev_queue_xmit+0x13bb/0x1b80 net/core/dev.c:4032
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4096
 neigh_hh_output include/net/neighbour.h:499 [inline]
 neigh_output include/net/neighbour.h:508 [inline]
 ip_finish_output2+0x87d/0xed0 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x22f/0x460 net/ipv4/ip_output.c:288
 ip_finish_output+0x3e/0x160 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0xf2/0x240 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0x70/0x90 net/ipv4/ip_output.c:125
 __ip_queue_xmit+0x3a6/0xa40 net/ipv4/ip_output.c:530
 ip_queue_xmit+0x3e/0x50 include/net/ip.h:237
 __tcp_transmit_skb+0xe1f/0x1c90 net/ipv4/tcp_output.c:1234
 __tcp_send_ack+0x22c/0x2f0 net/ipv4/tcp_output.c:3771
 tcp_send_ack+0x2d/0x40 net/ipv4/tcp_output.c:3777
 tcp_cleanup_rbuf+0x124/0x340 net/ipv4/tcp.c:1575
 tcp_recvmsg+0x687/0x1cc0 net/ipv4/tcp.c:2183
 inet_recvmsg+0xc1/0x250 net/ipv4/af_inet.c:838
 sock_recvmsg_nosec net/socket.c:886 [inline]
 sock_recvmsg net/socket.c:904 [inline]
 sock_recvmsg+0x8e/0xb0 net/socket.c:900
 sock_read_iter+0x185/0x230 net/socket.c:982
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read+0x416/0x450 fs/read_write.c:414
 __vfs_read+0x9e/0xb0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x13e/0x2b0 fs/read_write.c:446
 ksys_read+0x16a/0x1a0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x49/0x60 fs/read_write.c:595
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85d056d0 of 4 bytes by task 0 on cpu 1:
 tick_nohz_stop_tick kernel/time/tick-sched.c:774 [inline]
 __tick_nohz_idle_stop_tick kernel/time/tick-sched.c:967 [inline]
 tick_nohz_idle_stop_tick+0x191/0x680 kernel/time/tick-sched.c:988
 cpuidle_idle_call kernel/sched/idle.c:151 [inline]
 do_idle+0x1ad/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
 start_secondary+0x164/0x1b0 arch/x86/kernel/smpboot.c:264
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================