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mm/memcg: alignment memcg_data define condition

PATCH In review [email protected] 2 participants 2 messages Jul 12, 2024

Subsystems (3)
Memory management MM core Slab allocator
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PATCH v3 1/1 mm/memcg: alignment memcg_data define condition

From: "Alex Shi (Tencent)" <[email protected]>

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_ext 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) <[email protected]>
Cc Randy Dunlap <[email protected]>
Cc Yoann Congal <[email protected]>
Cc Masahiro Yamada <[email protected]>
Cc Petr Mladek <[email protected]>
Cc Suren Baghdasaryan <[email protected]>
Cc Vlastimil Babka <[email protected]>
---
 include/linux/mm_types.h | 8 ++++++--
 mm/slab.h                | 4 +++-
 2 files changed, 9 insertions(+), 3 deletions(-)
include/linux/mm_types.h +6 -2
index ef09c4eef6d3..4ac3abc673d3 100644
@@ -180,8 +180,10 @@ 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_ext;
 #endif
 
 	/*

@@ -343,8 +345,10 @@ 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_ext;
 #endif
 #if defined(WANT_PAGE_VIRTUAL)
 			void *virtual;
mm/slab.h +3 -1
index 3586e6183224..3aae11dde532 100644
@@ -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_ext, obj_exts);
 #endif
 #undef SLAB_MATCH
 static_assert(sizeof(struct slab) <= sizeof(struct page));
Signature · 1 line
2.43.0
#1 lore raw
Quoted 10 lines · On 7/12/24 6:14 AM, [email protected] wrote:

From: "Alex Shi (Tencent)" <[email protected]>

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_ext for SLAB_MATCH for slab.obj_exts while !MEMCG. That could resolve the match issue, clean up the feature logical.

Quoted 7 lines
Signed-off-by Alex Shi (Tencent) <[email protected]>
Cc Randy Dunlap <[email protected]>
Cc Yoann Congal <[email protected]>
Cc Masahiro Yamada <[email protected]>
Cc Petr Mladek <[email protected]>
Cc Suren Baghdasaryan <[email protected]>
Cc Vlastimil Babka <[email protected]>

Thanks, added to slab/for-next