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BUG: KCSAN: data-race in mod_timer / run_timer_softirq

read to 0xffff88812c11da88 of 8 bytes by task 5 on cpu 0:
 __mod_timer kernel/time/timer.c:1026 [inline]
 mod_timer+0x1ec/0x7a0 kernel/time/timer.c:1100
 mld_ifc_start_timer+0x4d/0xf0 net/ipv6/mcast.c:1053
 mld_ifc_event net/ipv6/mcast.c:2492 [inline]
 mld_ifc_event+0x74/0x90 net/ipv6/mcast.c:2487
 igmp6_group_added+0x1c0/0x260 net/ipv6/mcast.c:692
 __ipv6_dev_mc_inc+0x4e0/0x760 net/ipv6/mcast.c:931
 ipv6_dev_mc_inc+0x29/0x40 net/ipv6/mcast.c:938
 addrconf_join_solict.part.0+0x7d/0xa0 net/ipv6/addrconf.c:2149
 addrconf_join_solict net/ipv6/addrconf.c:3939 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:3939 [inline]
 addrconf_dad_work+0x10b/0xba0 net/ipv6/addrconf.c:4066
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff88812c11da88 of 8 bytes by interrupt on cpu 1:
 expire_timers kernel/time/timer.c:1445 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0x496/0xcd0 kernel/time/timer.c:1786
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:690
 default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x1c2/0x290 kernel/sched/idle.c:269
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 start_secondary+0x168/0x1b0 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 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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