mm/mempolicy: fix weighted interleave auto sysfs name

The __ATTR macro is a utility that makes defining kobj_attributes easier
by stringfying the name, verifying the mode, and setting the show/store
fields in a single initializer.  It takes a raw token as the first value,
rather than a string, so that __ATTR family macros like __ATTR_RW can
token-paste it for inferring the _show / _store function names.

Commit e341f9c ("mm/mempolicy: Weighted Interleave Auto-tuning") used
the __ATTR macro to define the "auto" sysfs for weighted interleave.  A
few months later, commit 2fb6915 ("compiler_types.h: add "auto" as a
macro for "__auto_type"") introduced a #define macro which expanded auto
into __auto_type.

This led to the "auto" token passed into __ATTR to be expanded out into
__auto_type, and the sysfs entry to be displayed as __auto_type as well.

Expand out the __ATTR macro and directly pass a string "auto" instead of
the raw token 'auto' to prevent it from being expanded out.  Also bypass
the VERIFY_OCTAL_PERMISSIONS check by triple checking that 0664 is indeed
the intended permissions for this sysfs file.

Before:
$ ls /sys/kernel/mm/mempolicy/weighted_interleave
__auto_type  node0

After:
$ ls /sys/kernel/mm/mempolicy/weighted_interleave/
auto  node0

Link: https://lore.kernel.org/20260407141415.3080960-1-joshua.hahnjy@gmail.com
Fixes: 2fb6915 ("compiler_types.h: add "auto" as a macro for "__auto_type"")
Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Rakie Kim <rakie.kim@sk.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: joshuahahn

mm/mempolicy.c

@@ -3781,9 +3781,11 @@ static void wi_state_free(void)
 	}
 }
 
-static struct kobj_attribute wi_auto_attr =
-	__ATTR(auto, 0664, weighted_interleave_auto_show,
-			   weighted_interleave_auto_store);
+static struct kobj_attribute wi_auto_attr = {
+	.attr = { .name = "auto", .mode = 0664 },
+	.show = weighted_interleave_auto_show,
+	.store = weighted_interleave_auto_store,
+};
 
 static void wi_cleanup(void) {
 	sysfs_remove_file(&wi_group->wi_kobj, &wi_auto_attr.attr);