Introduce objext_flags to store additional objext flags unrelated to memcg.

Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
---
 include/linux/memcontrol.h | 29 ++++++++++++++++++++++-------
 mm/slab.h                  |  4 +---
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index eb1dc181e412..f3584e98b640 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -356,7 +356,22 @@ enum page_memcg_data_flags {
        __NR_MEMCG_DATA_FLAGS  = (1UL << 2),
 };
 
-#define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1)
+#define __FIRST_OBJEXT_FLAG    __NR_MEMCG_DATA_FLAGS
+
+#else /* CONFIG_MEMCG */
+
+#define __FIRST_OBJEXT_FLAG    (1UL << 0)
+
+#endif /* CONFIG_MEMCG */
+
+enum objext_flags {
+       /* the next bit after the last actual flag */
+       __NR_OBJEXTS_FLAGS  = __FIRST_OBJEXT_FLAG,
+};
+
+#define OBJEXTS_FLAGS_MASK (__NR_OBJEXTS_FLAGS - 1)
+
+#ifdef CONFIG_MEMCG
 
 static inline bool folio_memcg_kmem(struct folio *folio);
 
@@ -390,7 +405,7 @@ static inline struct mem_cgroup *__folio_memcg(struct folio 
*folio)
        VM_BUG_ON_FOLIO(memcg_data & MEMCG_DATA_OBJEXTS, folio);
        VM_BUG_ON_FOLIO(memcg_data & MEMCG_DATA_KMEM, folio);
 
-       return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+       return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
 }
 
 /*
@@ -411,7 +426,7 @@ static inline struct obj_cgroup *__folio_objcg(struct folio 
*folio)
        VM_BUG_ON_FOLIO(memcg_data & MEMCG_DATA_OBJEXTS, folio);
        VM_BUG_ON_FOLIO(!(memcg_data & MEMCG_DATA_KMEM), folio);
 
-       return (struct obj_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+       return (struct obj_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
 }
 
 /*
@@ -468,11 +483,11 @@ static inline struct mem_cgroup *folio_memcg_rcu(struct 
folio *folio)
        if (memcg_data & MEMCG_DATA_KMEM) {
                struct obj_cgroup *objcg;
 
-               objcg = (void *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+               objcg = (void *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
                return obj_cgroup_memcg(objcg);
        }
 
-       return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+       return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
 }
 
 /*
@@ -511,11 +526,11 @@ static inline struct mem_cgroup *folio_memcg_check(struct 
folio *folio)
        if (memcg_data & MEMCG_DATA_KMEM) {
                struct obj_cgroup *objcg;
 
-               objcg = (void *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+               objcg = (void *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
                return obj_cgroup_memcg(objcg);
        }
 
-       return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
+       return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK);
 }
 
 static inline struct mem_cgroup *page_memcg_check(struct page *page)
diff --git a/mm/slab.h b/mm/slab.h
index 7f19b0a2acd8..13b6ba2abd74 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -560,10 +560,8 @@ static inline struct slabobj_ext *slab_obj_exts(struct 
slab *slab)
                                                        slab_page(slab));
        VM_BUG_ON_PAGE(obj_exts & MEMCG_DATA_KMEM, slab_page(slab));
 
-       return (struct slabobj_ext *)(obj_exts & ~MEMCG_DATA_FLAGS_MASK);
-#else
-       return (struct slabobj_ext *)obj_exts;
 #endif
+       return (struct slabobj_ext *)(obj_exts & ~OBJEXTS_FLAGS_MASK);
 }
 
 int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
-- 
2.44.0.rc0.258.g7320e95886-goog


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