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BUG: KCSAN: data-race in futex_wait_queue_me / mm_update_next_owner

read-write to 0xffff8880494e3024 of 4 bytes by task 5220 on cpu 0:
 freezer_do_not_count include/linux/freezer.h:109 [inline]
 freezable_schedule include/linux/freezer.h:171 [inline]
 futex_wait_queue_me+0x17e/0x240 kernel/futex.c:2588
 futex_wait+0x145/0x390 kernel/futex.c:2690
 do_futex+0x113c/0x2180 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 0xffff8880494e3024 of 4 bytes by task 5227 on cpu 1:
 mm_update_next_owner+0x1e9/0x4c0 kernel/exit.c:387
 exit_mm+0x2b5/0x320 kernel/exit.c:482
 do_exit+0x40e/0x1670 kernel/exit.c:793
 do_group_exit+0x16f/0x170 kernel/exit.c:903
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:914
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:912
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
 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: 5227 Comm: syz-executor.4 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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