syzbot

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BUG: KCSAN: data-race in copy_process / task_dump_owner

write to 0xffff8880a9c78024 of 4 bytes by task 16801 on cpu 0:
 copy_process+0x5b1/0x2dc0 kernel/fork.c:1948
 _do_fork+0x14a/0x6c0 kernel/fork.c:2429
 __do_sys_clone kernel/fork.c:2546 [inline]
 __se_sys_clone kernel/fork.c:2530 [inline]
 __x64_sys_clone+0xc8/0xf0 kernel/fork.c:2530
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a9c78024 of 4 bytes by task 16837 on cpu 1:
 task_dump_owner+0x2b/0x1b0 fs/proc/base.c:1818
 tid_fd_update_inode fs/proc/fd.c:104 [inline]
 tid_fd_revalidate+0x149/0x2b0 fs/proc/fd.c:133
 lookup_fast+0x208/0x370 fs/namei.c:768
 open_last_lookups fs/namei.c:3143 [inline]
 path_openat+0x467/0x20a0 fs/namei.c:3365
 do_filp_open+0xbd/0x1d0 fs/namei.c:3395
 do_sys_openat2+0x33b/0x500 fs/open.c:1168
 do_sys_open fs/open.c:1184 [inline]
 __do_sys_open fs/open.c:1192 [inline]
 __se_sys_open fs/open.c:1188 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1188
 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: 16837 Comm: syz-executor.5 Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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