syzbot

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BUG: KCSAN: data-race in generic_permission / pid_update_inode

write to 0xffff8881241877f8 of 2 bytes by task 8141 on cpu 0:
 pid_update_inode+0x51/0x70 fs/proc/base.c:1820
 pid_revalidate+0x91/0xd0 fs/proc/base.c:1841
 d_revalidate fs/namei.c:758 [inline]
 d_revalidate fs/namei.c:755 [inline]
 lookup_fast+0x6f2/0x700 fs/namei.c:1607
 walk_component+0x6d/0xe70 fs/namei.c:1796
 lookup_last fs/namei.c:2263 [inline]
 path_lookupat.isra.0+0x13a/0x5a0 fs/namei.c:2308
 filename_lookup+0x145/0x2b0 fs/namei.c:2338
 user_path_at_empty+0x4c/0x70 fs/namei.c:2598
 user_path_at include/linux/namei.h:49 [inline]
 vfs_statx+0xd9/0x190 fs/stat.c:187
 vfs_stat include/linux/fs.h:3242 [inline]
 __do_sys_newstat+0x51/0xb0 fs/stat.c:341
 __se_sys_newstat fs/stat.c:337 [inline]
 __x64_sys_newstat+0x3a/0x50 fs/stat.c:337
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881241877f8 of 2 bytes by task 8147 on cpu 1:
 acl_permission_check fs/namei.c:295 [inline]
 generic_permission+0x36/0x3d0 fs/namei.c:339
 proc_pid_permission+0xea/0x1c0 fs/proc/base.c:735
 do_inode_permission fs/namei.c:384 [inline]
 inode_permission+0x241/0x3c0 fs/namei.c:449
 may_lookup fs/namei.c:1694 [inline]
 link_path_walk.part.0+0x622/0xa90 fs/namei.c:2074
 link_path_walk fs/namei.c:2062 [inline]
 path_openat+0x14f/0x36e0 fs/namei.c:3524
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8147 Comm: ps Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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