mm/memcg: alignment memcg_data define condition

commit 21c690a349ba ("mm: introduce slabobj_ext to support slab object
extensions") changed the folio/page->memcg_data define condition from
MEMCG to SLAB_OBJ_EXT. This action make memcg_data exposed while !MEMCG.

As Vlastimil Babka suggested, let's add _unused_slab_obj_exts for
SLAB_MATCH for slab.obj_exts while !MEMCG. That could resolve the match
issue, clean up the feature logical.

Signed-off-by: Alex Shi (Tencent) <alexs@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index af3a0256fa93be1c93449b3c97825e1f6b64832c..a199c48bc462d4244aa95f07898fad80b1cf106b 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -169,8 +169,10 @@ struct page {
        /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
        atomic_t _refcount;
 
-#ifdef CONFIG_SLAB_OBJ_EXT
+#ifdef CONFIG_MEMCG
        unsigned long memcg_data;
+#elif defined(CONFIG_SLAB_OBJ_EXT)
+       unsigned long _unused_slab_obj_exts;
 #endif
 
        /*
@@ -298,6 +300,7 @@ typedef struct {
  * @_hugetlb_cgroup_rsvd: Do not use directly, use accessor in hugetlb_cgroup.h.
  * @_hugetlb_hwpoison: Do not use directly, call raw_hwp_list_head().
  * @_deferred_list: Folios to be split under memory pressure.
+ * @_unused_slab_obj_exts: Placeholder to match obj_exts in struct slab.
  *
  * A folio is a physically, virtually and logically contiguous set
  * of bytes.  It is a power-of-two in size, and it is aligned to that
@@ -332,8 +335,10 @@ struct folio {
                        };
                        atomic_t _mapcount;
                        atomic_t _refcount;
-#ifdef CONFIG_SLAB_OBJ_EXT
+#ifdef CONFIG_MEMCG
                        unsigned long memcg_data;
+#elif defined(CONFIG_SLAB_OBJ_EXT)
+                       unsigned long _unused_slab_obj_exts;
 #endif
 #if defined(WANT_PAGE_VIRTUAL)
                        void *virtual;

diff --git a/mm/slab.h b/mm/slab.h
index 5f8f47c5bee0a274c6c2df810b85b1e53681c370..a240945487e02a46b4d17b594ca4c3f7f6f54e6d 100644 (file)
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -97,8 +97,10 @@ struct slab {
 SLAB_MATCH(flags, __page_flags);
 SLAB_MATCH(compound_head, slab_cache); /* Ensure bit 0 is clear */
 SLAB_MATCH(_refcount, __page_refcount);
-#ifdef CONFIG_SLAB_OBJ_EXT
+#ifdef CONFIG_MEMCG
 SLAB_MATCH(memcg_data, obj_exts);
+#elif defined(CONFIG_SLAB_OBJ_EXT)
+SLAB_MATCH(_unused_slab_obj_exts, obj_exts);
 #endif
 #undef SLAB_MATCH
 static_assert(sizeof(struct slab) <= sizeof(struct page));