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BUG: KCSAN: data-race in expire_timers / try_to_del_timer_sync

write to 0xffff888237c376c8 of 8 bytes by interrupt on cpu 0:
 expire_timers+0x13d/0x250 kernel/time/timer.c:1465
 __run_timers+0x358/0x420 kernel/time/timer.c:1732
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1745
 __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
 finish_task_switch+0xda/0x290 kernel/sched/core.c:4557
 context_switch kernel/sched/core.c:4686 [inline]
 __schedule+0x42a/0x670 kernel/sched/core.c:5940
 preempt_schedule_common kernel/sched/core.c:6100 [inline]
 __cond_resched+0x2a/0x40 kernel/sched/core.c:7781
 prepare_alloc_pages mm/page_alloc.c:5170 [inline]
 __alloc_pages+0xf7/0x320 mm/page_alloc.c:5380
 alloc_pages_vma+0x513/0x680 mm/mempolicy.c:2208
 shmem_alloc_page mm/shmem.c:1563 [inline]
 shmem_alloc_and_acct_page mm/shmem.c:1588 [inline]
 shmem_getpage_gfp+0x954/0x13d0 mm/shmem.c:1917
 shmem_fault+0x16d/0x500 mm/shmem.c:2138
 __do_fault mm/memory.c:3857 [inline]
 do_read_fault mm/memory.c:4172 [inline]
 do_fault mm/memory.c:4300 [inline]
 handle_pte_fault mm/memory.c:4558 [inline]
 __handle_mm_fault mm/memory.c:4693 [inline]
 handle_mm_fault+0xe6d/0x1a50 mm/memory.c:4791
 faultin_page mm/gup.c:951 [inline]
 __get_user_pages+0x32b/0xbc0 mm/gup.c:1173
 populate_vma_page_range mm/gup.c:1506 [inline]
 __mm_populate+0x24d/0x380 mm/gup.c:1612
 mm_populate include/linux/mm.h:2623 [inline]
 vm_mmap_pgoff+0x142/0x1d0 mm/util.c:524
 ksys_mmap_pgoff+0xe1/0x380 mm/mmap.c:1635
 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 0xffff888237c376c8 of 8 bytes by task 11 on cpu 1:
 try_to_del_timer_sync+0xe3/0x290 kernel/time/timer.c:1233
 del_timer_sync kernel/time/timer.c:1380 [inline]
 schedule_timeout+0x108/0x240 kernel/time/timer.c:1880
 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline]
 rcu_gp_kthread+0xbf7/0xec0 kernel/rcu/tree.c:2169
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

value changed: 0xffffc90000277e60 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11 Comm: rcu_sched Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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