syzbot

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BUG: KCSAN: data-race in futex_wait_queue_me / ptrace_attach

read-write to 0xffff88801bd5002c of 4 bytes by task 2329 on cpu 0:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 futex_wait_queue_me+0x198/0x240 kernel/futex.c:2602
 futex_wait+0x145/0x3d0 kernel/futex.c:2704
 do_futex+0x105a/0x20c0 kernel/futex.c:3763
 __do_sys_futex kernel/futex.c:3826 [inline]
 __se_sys_futex+0x2a8/0x390 kernel/futex.c:3792
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3792
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88801bd5002c of 4 bytes by task 2326 on cpu 1:
 ptrace_attach+0xd0/0x4b0 kernel/ptrace.c:378
 __do_sys_ptrace kernel/ptrace.c:1256 [inline]
 __se_sys_ptrace+0xc1/0x2e0 kernel/ptrace.c:1236
 __x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1236
 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: 2326 Comm: syz-executor.0 Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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