syzbot

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BUG: KCSAN: data-race in _do_fork / mm_release

write to 0xffff8880aea7a5a8 of 8 bytes by task 13596 on cpu 1:
 wait_for_vfork_done kernel/fork.c:1271 [inline]
 _do_fork+0x5c6/0x790 kernel/fork.c:2461
 __do_sys_clone+0xf9/0x130 kernel/fork.c:2585
 __se_sys_clone kernel/fork.c:2566 [inline]
 __x64_sys_clone+0x6c/0x80 kernel/fork.c:2566
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880aea7a5a8 of 8 bytes by task 13598 on cpu 0:
 mm_release+0xe8/0x200 kernel/fork.c:1322
 exit_mm_release+0x2b/0x40 kernel/fork.c:1329
 exit_mm kernel/exit.c:434 [inline]
 do_exit+0x433/0x11e0 kernel/exit.c:782
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 get_signal+0x2a7/0x1290 kernel/signal.c:2739
 do_signal+0x2b/0x840 arch/x86/kernel/signal.c:784
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13598 Comm: syz-executor.3 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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