[PATCH v4 10/36] slab: objext: introduce objext_flags as extension to page_memcg_data_flags

Suren Baghdasaryan
2024-02-21T19:41:19Z

Introduce objext_flags to store additional objext flags unrelated to memcg.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
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