mm/mempolicy: fix weighted interleave auto sysfs name

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 e341f9c3c841 ("mm/mempolicy: Weighted Interleave Auto-tuning") used
the __ATTR macro to define the "auto" sysfs for weighted interleave.  A
few months later, commit 2fb6915fa22d ("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: 2fb6915fa22d ("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>