syzbot

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BUG: KCSAN: data-race in kernfs_refresh_inode / privileged_wrt_inode_uidgid

write to 0xffff88812a700004 of 4 bytes by task 7134 on cpu 1:
 set_inode_attr fs/kernfs/inode.c:161 [inline]
 kernfs_refresh_inode+0x5f/0x140 fs/kernfs/inode.c:178
 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_lookup fs/namei.c:1694 [inline]
 link_path_walk.part.0+0x622/0xa90 fs/namei.c:2074
 link_path_walk fs/namei.c:2259 [inline]
 path_lookupat.isra.0+0x77/0x5a0 fs/namei.c:2307
 filename_lookup+0x145/0x2b0 fs/namei.c:2338
 user_path_at_empty+0x4c/0x70 fs/namei.c:2598
 do_readlinkat+0x84/0x220 fs/stat.c:399
 __do_sys_readlink fs/stat.c:432 [inline]
 __se_sys_readlink fs/stat.c:429 [inline]
 __x64_sys_readlink+0x51/0x70 fs/stat.c:429
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812a700004 of 4 bytes by task 3889 on cpu 0:
 privileged_wrt_inode_uidgid+0x2b/0x90 kernel/capability.c:489
 capable_wrt_inode_uidgid+0x93/0xa0 kernel/capability.c:506
 generic_permission fs/namei.c:346 [inline]
 generic_permission+0x2b0/0x3d0 fs/namei.c:332
 kernfs_iop_permission+0x7d/0xa0 fs/kernfs/inode.c:286
 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:2259 [inline]
 path_lookupat.isra.0+0x77/0x5a0 fs/namei.c:2307
 filename_lookup+0x145/0x2b0 fs/namei.c:2338
 user_path_at_empty+0x4c/0x70 fs/namei.c:2598
 do_readlinkat+0x84/0x220 fs/stat.c:399
 __do_sys_readlink fs/stat.c:432 [inline]
 __se_sys_readlink fs/stat.c:429 [inline]
 __x64_sys_readlink+0x51/0x70 fs/stat.c:429
 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: 0 PID: 3889 Comm: udevd Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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