syzbot

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BUG: KCSAN: data-race in snd_seq_cell_alloc / snd_seq_info_pool

read-write to 0xffff8880273e71b0 of 4 bytes by task 29607 on cpu 0:
 snd_seq_cell_alloc+0x2f1/0x350 sound/core/seq/seq_memory.c:260
 snd_seq_event_dup+0xe0/0x400 sound/core/seq/seq_memory.c:298
 snd_seq_client_enqueue_event+0x1dd/0x2a0 sound/core/seq/seq_clientmgr.c:968
 snd_seq_write+0x425/0x530 sound/core/seq/seq_clientmgr.c:1093
 vfs_write+0x21a/0x7c0 fs/read_write.c:603
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880273e71b0 of 4 bytes by task 29606 on cpu 1:
 snd_seq_info_pool+0xb8/0x110 sound/core/seq/seq_memory.c:500
 snd_seq_info_clients_read+0x37b/0x490 sound/core/seq/seq_clientmgr.c:2473
 snd_info_seq_show+0x77/0x90 sound/core/info.c:362
 seq_read_iter+0x2ef/0x8e0 fs/seq_file.c:228
 seq_read+0x221/0x260 fs/seq_file.c:159
 pde_read fs/proc/inode.c:321 [inline]
 proc_reg_read+0x119/0x1b0 fs/proc/inode.c:333
 do_loop_readv_writev fs/read_write.c:761 [inline]
 do_iter_read+0x3b1/0x4b0 fs/read_write.c:803
 vfs_readv fs/read_write.c:921 [inline]
 do_preadv+0x139/0x210 fs/read_write.c:1013
 __do_sys_preadv fs/read_write.c:1063 [inline]
 __se_sys_preadv fs/read_write.c:1058 [inline]
 __x64_sys_preadv+0x54/0x60 fs/read_write.c:1058
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29606 Comm: syz-executor.5 Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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