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BUG: KCSAN: data-race in internal_add_timer / update_process_times

write to 0xffff888237c376d8 of 8 bytes by interrupt on cpu 1:
 enqueue_timer kernel/time/timer.c:598 [inline]
 internal_add_timer+0x146/0x270 kernel/time/timer.c:611
 add_timer_on+0x262/0x2a0 kernel/time/timer.c:1182
 clocksource_watchdog+0xa74/0xac0 kernel/time/clocksource.c:478
 call_timer_fn+0x2e/0x1d0 kernel/time/timer.c:1421
 expire_timers+0x135/0x240 kernel/time/timer.c:1466
 __run_timers+0x358/0x420 kernel/time/timer.c:1734
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1747
 __do_softirq+0x12c/0x26e kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x9a/0xb0 kernel/softirq.c:636
 sysvec_apic_timer_interrupt+0x69/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
 _raw_spin_unlock_irqrestore+0x34/0x40 kernel/locking/spinlock.c:192
 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
 mix_pool_bytes+0x5d/0xe0 drivers/char/random.c:598
 write_pool+0x299/0x310 drivers/char/random.c:1884
 random_ioctl+0x103/0x3a0 drivers/char/random.c:1931
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c376d8 of 8 bytes by interrupt on cpu 0:
 run_local_timers kernel/time/timer.c:1761 [inline]
 update_process_times+0x8c/0x150 kernel/time/timer.c:1784
 tick_sched_handle kernel/time/tick-sched.c:226 [inline]
 tick_sched_timer+0x191/0x210 kernel/time/tick-sched.c:1421
 __run_hrtimer+0x160/0x480 kernel/time/hrtimer.c:1537
 __hrtimer_run_queues kernel/time/hrtimer.c:1601 [inline]
 hrtimer_interrupt+0x380/0xaf0 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x6f/0x1c0 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x64/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
 _raw_spin_unlock_irqrestore+0x34/0x40 kernel/locking/spinlock.c:192
 spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
 mix_pool_bytes+0x5d/0xe0 drivers/char/random.c:598
 write_pool+0x299/0x310 drivers/char/random.c:1884
 random_ioctl+0x103/0x3a0 drivers/char/random.c:1931
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000000010003acd4 -> 0x000000010003acd3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15678 Comm: syz-executor.0 Not tainted 5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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