syzbot

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BUG: KCSAN: data-race in __snd_pcm_lib_xfer / snd_pcm_oss_sync

write to 0xffff88810df87000 of 8 bytes by task 17615 on cpu 0:
 pcm_lib_apply_appl_ptr sound/core/pcm_lib.c:2101 [inline]
 __snd_pcm_lib_xfer+0xe68/0x11e0 sound/core/pcm_lib.c:2236
 snd_pcm_oss_write3+0x197/0x230 sound/core/oss/pcm_oss.c:1227
 io_playback_transfer+0x7a/0x2d0 sound/core/oss/io.c:47
 snd_pcm_plug_write_transfer+0x1d0/0x360 sound/core/oss/pcm_plugin.c:624
 snd_pcm_oss_write2+0xe0/0x250 sound/core/oss/pcm_oss.c:1359
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1425 [inline]
 snd_pcm_oss_write+0x322/0x8b0 sound/core/oss/pcm_oss.c:2775
 vfs_write+0x223/0x7e0 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+0x44/0xae

read to 0xffff88810df87000 of 8 bytes by task 17627 on cpu 1:
 snd_pcm_oss_sync+0x5ce/0x6a0 sound/core/oss/pcm_oss.c:1684
 snd_pcm_oss_ioctl+0x61a/0x29d0 sound/core/oss/pcm_oss.c:2600
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17627 Comm: syz-executor.1 Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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