syzbot

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BUG: KCSAN: data-race in copy_process / get_task_exe_file

write to 0xffff888139ef106c of 4 bytes by task 10516 on cpu 1:
 copy_process+0x608/0x2e00 kernel/fork.c:1986
 kernel_clone+0x14b/0x680 kernel/fork.c:2503
 __do_sys_clone kernel/fork.c:2620 [inline]
 __se_sys_clone kernel/fork.c:2604 [inline]
 __x64_sys_clone+0xb4/0xe0 kernel/fork.c:2604
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888139ef106c of 4 bytes by task 10517 on cpu 0:
 get_task_exe_file+0x44/0x140 kernel/fork.c:1202
 proc_exe_link+0x44/0x100 fs/proc/base.c:1725
 proc_pid_get_link+0x50/0xb0 fs/proc/base.c:1750
 pick_link fs/namei.c:1736 [inline]
 step_into+0x974/0xec0 fs/namei.c:1798
 open_last_lookups fs/namei.c:3308 [inline]
 path_openat+0xfc8/0x20b0 fs/namei.c:3491
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_openat fs/open.c:1219 [inline]
 __se_sys_openat fs/open.c:1214 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1214
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00404040 -> 0x40404040

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10517 Comm: syz-executor.0 Not tainted 5.13.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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