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BUG: KCSAN: data-race in snd_pcm_oss_ioctl / snd_pcm_oss_make_ready

write to 0xffff88809900a300 of 1 bytes by task 19762 on cpu 0:
 snd_pcm_oss_set_fragment1 sound/core/oss/pcm_oss.c:1947 [inline]
 snd_pcm_oss_set_fragment sound/core/oss/pcm_oss.c:1965 [inline]
 snd_pcm_oss_ioctl+0x1171/0x2090 sound/core/oss/pcm_oss.c:2652
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x109/0x150 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:770
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809900a300 of 1 bytes by task 19725 on cpu 1:
 snd_pcm_oss_make_ready+0xbd/0x120 sound/core/oss/pcm_oss.c:1147
 snd_pcm_oss_set_trigger.isra.0+0x2d6/0x500 sound/core/oss/pcm_oss.c:2046
 snd_pcm_oss_poll+0x40c/0x5d0 sound/core/oss/pcm_oss.c:2830
 vfs_poll include/linux/poll.h:90 [inline]
 do_select+0x7d0/0x1020 fs/select.c:534
 core_sys_select+0x312/0x680 fs/select.c:677
 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
 __do_sys_pselect6 fs/select.c:784 [inline]
 __se_sys_pselect6 fs/select.c:769 [inline]
 __x64_sys_pselect6+0x12e/0x170 fs/select.c:769
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19725 Comm: syz-executor.0 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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