mm: use octal not symbolic permissions

mm/*.c files use symbolic and octal styles for permissions.

Using octal and not symbolic permissions is preferred by many as more
readable.

https://lkml.org/lkml/2016/8/2/1945

Prefer the direct use of octal for permissions.

Done using
$ scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace mm/*.c
and some typing.

Before:	 $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
44
After:	 $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
86

Miscellanea:

o Whitespace neatening around these conversions.

Link: http://lkml.kernel.org/r/2e032ef111eebcd4c5952bae86763b541d373469.1522102887.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/failslab.c b/mm/failslab.c
index 1f2f248..b135ebb 100644
--- a/mm/failslab.c
+++ b/mm/failslab.c
@@ -42,7 +42,7 @@ __setup("failslab=", setup_failslab);
 static int __init failslab_debugfs_init(void)
 {
 	struct dentry *dir;
-	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+	umode_t mode = S_IFREG | 0600;
 
 	dir = fault_create_debugfs_attr("failslab", NULL, &failslab.attr);
 	if (IS_ERR(dir))