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BUG: KCSAN: data-race in do_select / pollwake

write to 0xffffc90000edba60 of 4 bytes by task 27310 on cpu 0:
 __pollwake fs/select.c:197 [inline]
 pollwake+0xa7/0xf0 fs/select.c:217
 __wake_up_common+0xbc/0x130 kernel/sched/wait.c:93
 __wake_up_common_lock kernel/sched/wait.c:123 [inline]
 __wake_up+0x80/0xc0 kernel/sched/wait.c:142
 snd_seq_cell_free+0x1e4/0x220 sound/core/seq/seq_memory.c:198
 snd_seq_dispatch_event+0x156/0x270 sound/core/seq/seq_clientmgr.c:914
 snd_seq_check_queue+0xfe/0x290 sound/core/seq/seq_queue.c:264
 snd_seq_enqueue_event+0x275/0x2b0 sound/core/seq/seq_queue.c:333
 snd_seq_client_enqueue_event+0x206/0x2a0 sound/core/seq/seq_clientmgr.c:974
 snd_seq_write+0x435/0x550 sound/core/seq/seq_clientmgr.c:1093
 __vfs_write+0x69/0x340 fs/read_write.c:495
 vfs_write+0x19b/0x350 fs/read_write.c:559
 ksys_write+0xce/0x180 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:621
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffc90000edba60 of 4 bytes by task 27321 on cpu 1:
 poll_schedule_timeout fs/select.c:242 [inline]
 do_select+0xea6/0xf70 fs/select.c:603
 core_sys_select+0x3e3/0x610 fs/select.c:677
 do_pselect fs/select.c:759 [inline]
 __do_sys_pselect6 fs/select.c:800 [inline]
 __se_sys_pselect6+0x248/0x290 fs/select.c:791
 __x64_sys_pselect6+0x74/0x80 fs/select.c:791
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27321 Comm: syz-executor.5 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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