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BUG: KCSAN: data-race in snd_seq_timer_get_cur_tick / snd_seq_timer_interrupt

read to 0xffff8881219d76d8 of 4 bytes by task 2504 on cpu 0:
 snd_seq_timer_get_cur_tick+0x21/0x40 sound/core/seq/seq_timer.c:449
 update_timestamp_of_queue+0x93/0x110 sound/core/seq/seq_clientmgr.c:586
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:691 [inline]
 snd_seq_deliver_event+0x2cd/0x4c0 sound/core/seq/seq_clientmgr.c:828
 snd_seq_kernel_client_dispatch+0xef/0x110 sound/core/seq/seq_clientmgr.c:2323
 snd_vmidi_output_work+0x156/0x200 sound/core/seq/seq_virmidi.c:149
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

write to 0xffff8881219d76d8 of 4 bytes by interrupt on cpu 1:
 snd_seq_timer_update_tick sound/core/seq/seq_timer.h:58 [inline]
 snd_seq_timer_interrupt+0x202/0x280 sound/core/seq/seq_timer.c:150
 snd_timer_process_callbacks+0x1e4/0x220 sound/core/timer.c:757
 snd_timer_interrupt sound/core/timer.c:880 [inline]
 snd_timer_interrupt+0x483/0x930 sound/core/timer.c:801
 snd_hrtimer_callback+0x18f/0x260 sound/core/hrtimer.c:50
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x274/0x5f0 kernel/time/hrtimer.c:1576
 hrtimer_interrupt+0x22a/0x480 kernel/time/hrtimer.c:1638
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
 smp_apic_timer_interrupt+0xdc/0x280 arch/x86/kernel/apic/apic.c:1135
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:756 [inline]
 kcsan_setup_watchpoint+0x1d4/0x460 kernel/kcsan/core.c:436
 check_access kernel/kcsan/core.c:466 [inline]
 __tsan_write8 kernel/kcsan/core.c:596 [inline]
 __tsan_unaligned_write8+0xc4/0x100 kernel/kcsan/core.c:596
 rb_set_black lib/rbtree.c:61 [inline]
 ____rb_erase_color lib/rbtree.c:373 [inline]
 __rb_erase_color+0x51c/0x700 lib/rbtree.c:413
 rb_erase_augmented include/linux/rbtree_augmented.h:307 [inline]
 __vma_rb_erase+0x5c5/0x990 mm/mmap.c:473
 vma_rb_erase mm/mmap.c:499 [inline]
 detach_vmas_to_be_unmapped mm/mmap.c:2645 [inline]
 __do_munmap+0x565/0xb60 mm/mmap.c:2840
 __vm_munmap+0xb2/0x130 mm/mmap.c:2868
 __do_sys_munmap mm/mmap.c:2894 [inline]
 __se_sys_munmap mm/mmap.c:2890 [inline]
 __x64_sys_munmap+0x4c/0x60 mm/mmap.c:2890
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13637 Comm: blkid Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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