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BUG: KCSAN: data-race in kernfs_fop_open / kernfs_refresh_inode

write to 0xffff8880b70b2248 of 2 bytes by task 20150 on cpu 0:
 kernfs_refresh_inode+0x42/0x140 fs/kernfs/inode.c:172
 kernfs_iop_permission+0x66/0xa0 fs/kernfs/inode.c:283
 do_inode_permission fs/namei.c:384 [inline]
 inode_permission+0x241/0x3c0 fs/namei.c:449
 may_open.isra.0+0x144/0x250 fs/namei.c:2963
 do_last fs/namei.c:3404 [inline]
 path_openat+0xf05/0x36e0 fs/namei.c:3525
 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

read to 0xffff8880b70b2248 of 2 bytes by task 3889 on cpu 1:
 kernfs_fop_open+0x14b/0x7f0 fs/kernfs/file.c:637
 do_dentry_open+0x2f4/0x8f0 fs/open.c:797
 vfs_open+0x62/0x80 fs/open.c:914
 do_last fs/namei.c:3408 [inline]
 path_openat+0xf73/0x36e0 fs/namei.c:3525
 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: 3889 Comm: udevd 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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