syzbot

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BUG: KCSAN: data-race in attach_to_pi_owner / futex_wait_queue_me

write to 0xffff8881174ed0a4 of 4 bytes by task 15417 on cpu 0:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 futex_wait_queue_me+0x19e/0x290 kernel/futex.c:2631
 futex_wait_requeue_pi.constprop.0+0x283/0xa60 kernel/futex.c:3278
 do_futex+0x1c9/0x15b0 kernel/futex.c:3828
 __do_sys_futex kernel/futex.c:3869 [inline]
 __se_sys_futex kernel/futex.c:3837 [inline]
 __x64_sys_futex+0x2dc/0x410 kernel/futex.c:3837
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881174ed0a4 of 4 bytes by task 15423 on cpu 1:
 attach_to_pi_owner+0x7f/0x560 kernel/futex.c:1233
 lookup_pi_state kernel/futex.c:1320 [inline]
 futex_requeue+0xdfb/0x1050 kernel/futex.c:2077
 do_futex+0x2e6/0x15b0 kernel/futex.c:3831
 __do_sys_futex kernel/futex.c:3869 [inline]
 __se_sys_futex kernel/futex.c:3837 [inline]
 __x64_sys_futex+0x2dc/0x410 kernel/futex.c:3837
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15423 Comm: syz-executor.5 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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