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BUG: KCSAN: data-race in prandom_seed / prandom_u32

read to 0xffff888237d28858 of 8 bytes by task 1916 on cpu 0:
 prandom_seed+0xeb/0x270 lib/random32.c:440
 addrconf_dad_begin net/ipv6/addrconf.c:3975 [inline]
 addrconf_dad_work+0x265/0xbb0 net/ipv6/addrconf.c:4100
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

write to 0xffff888237d28858 of 8 bytes by interrupt on cpu 1:
 siprand_u32 lib/random32.c:372 [inline]
 prandom_u32+0x12f/0x190 lib/random32.c:387
 mrp_join_timer_arm net/802/mrp.c:595 [inline]
 mrp_join_timer+0x3ea/0x430 net/802/mrp.c:609
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1421
 expire_timers+0x116/0x240 kernel/time/timer.c:1466
 __run_timers+0x350/0x400 kernel/time/timer.c:1737
 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1750
 __do_softirq+0x158/0x2e3 kernel/softirq.c:558
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0x41/0x70 kernel/softirq.c:649
 sysvec_apic_timer_interrupt+0x8d/0xb0 arch/x86/kernel/apic/apic.c:1097
 asm_sysvec_apic_timer_interrupt+0x12/0x20
 native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
 arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
 acpi_safe_halt drivers/acpi/processor_idle.c:110 [inline]
 acpi_idle_do_entry drivers/acpi/processor_idle.c:551 [inline]
 acpi_idle_enter+0x27b/0x300 drivers/acpi/processor_idle.c:686
 cpuidle_enter_state+0x2ee/0x7a0 drivers/cpuidle/cpuidle.c:237
 cpuidle_enter+0x3c/0x60 drivers/cpuidle/cpuidle.c:351
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x1b2/0x250 kernel/sched/idle.c:303
 cpu_startup_entry+0x15/0x20 kernel/sched/idle.c:400
 start_secondary+0x78/0x80 arch/x86/kernel/smpboot.c:266
 secondary_startup_64_no_verify+0xc4/0xcb

value changed: 0x83b81255c99e33d9 -> 0x7dbd85fd6d502dc7

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.18.0-rc5-syzkaller-00178-g30c8e80f7932-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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