syzbot

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BUG: KCSAN: data-race in exit_signals / task_dump_owner

write to 0xffff88808e18e024 of 4 bytes by task 2348 on cpu 0:
 exit_signals+0x135/0x4c0 kernel/signal.c:2827
 do_exit+0x17b/0x11e0 kernel/exit.c:744
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 __do_sys_exit_group kernel/exit.c:904 [inline]
 __se_sys_exit_group kernel/exit.c:902 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:902
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88808e18e024 of 4 bytes by task 2352 on cpu 1:
 task_dump_owner+0x42/0x250 fs/proc/base.c:1789
 pid_update_inode+0x35/0x70 fs/proc/base.c:1931
 pid_revalidate+0x89/0x110 fs/proc/base.c:1954
 d_revalidate fs/namei.c:754 [inline]
 d_revalidate fs/namei.c:751 [inline]
 lookup_fast+0x22a/0x3a0 fs/namei.c:1491
 walk_component+0x6a/0x390 fs/namei.c:1842
 link_path_walk.part.0+0x469/0x700 fs/namei.c:2169
 link_path_walk fs/namei.c:2098 [inline]
 path_openat+0x191/0x23d0 fs/namei.c:3342
 do_filp_open+0x11e/0x1b0 fs/namei.c:3373
 do_sys_openat2+0x52e/0x680 fs/open.c:1148
 do_sys_open+0xa2/0x110 fs/open.c:1164
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1170 [inline]
 __se_sys_open fs/open.c:1168 [inline]
 __x64_sys_open+0x50/0x60 fs/open.c:1168
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2352 Comm: syz-executor.1 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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