syzbot

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BUG: KCSAN: data-race in futex_wait_queue_me / ptrace_attach

write to 0xffff8881217ab024 of 4 bytes by task 11336 on cpu 0:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 futex_wait_queue_me+0x1a8/0x250 kernel/futex.c:2588
 futex_wait+0x145/0x390 kernel/futex.c:2690
 do_futex+0x145c/0x21c0 kernel/futex.c:3749
 __do_sys_futex kernel/futex.c:3810 [inline]
 __se_sys_futex+0x26d/0x330 kernel/futex.c:3778
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3778
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881217ab024 of 4 bytes by task 11340 on cpu 1:
 ptrace_attach+0xd0/0x4b0 kernel/ptrace.c:384
 __do_sys_ptrace kernel/ptrace.c:1262 [inline]
 __se_sys_ptrace+0xc1/0x2d0 kernel/ptrace.c:1242
 __x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1242
 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: 11340 Comm: syz-executor.2 Not tainted 5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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