[PATCH] Add /proc/meminfo:Slab

Display the total slab memory in /proc/meminfo.  Handy while we play
with the slab pruning code.

This info is also available via /proc/slabinfo, but I think this
convenience is worth the extra few lines.

fs/proc/proc_misc.c

@@ -171,6 +171,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
 		"Dirty:        %8lu kB\n"
 		"Writeback:    %8lu kB\n"
 		"Mapped:       %8lu kB\n"
+		"Slab:         %8lu kB\n"
 		"Committed_AS: %8u kB\n"
 		"PageTables:   %8lu kB\n"
 		"ReverseMaps:  %8lu\n",
@@ -191,6 +192,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
 		K(ps.nr_dirty),
 		K(ps.nr_writeback),
 		K(ps.nr_mapped),
+		K(ps.nr_slab),
 		K(committed),
 		K(ps.nr_page_table_pages),
 		ps.nr_reverse_maps

include/linux/page-flags.h

@@ -79,6 +79,7 @@ extern struct page_state {
 	unsigned long nr_page_table_pages;
 	unsigned long nr_reverse_maps;
 	unsigned long nr_mapped;
+	unsigned long nr_slab;
 } ____cacheline_aligned_in_smp page_states[NR_CPUS];
 
 extern void get_page_state(struct page_state *ret);

mm/page_alloc.c

@@ -563,6 +563,7 @@ void get_page_state(struct page_state *ret)
 		ret->nr_page_table_pages += ps->nr_page_table_pages;
 		ret->nr_reverse_maps += ps->nr_reverse_maps;
 		ret->nr_mapped += ps->nr_mapped;
+		ret->nr_slab += ps->nr_slab;
 	}
 }
 

mm/slab.c

@@ -545,6 +545,7 @@ static inline void kmem_freepages (kmem_cache_t *cachep, void *addr)
 	 */
 	while (i--) {
 		ClearPageSlab(page);
+		dec_page_state(nr_slab);
 		page++;
 	}
 	free_pages((unsigned long)addr, cachep->gfporder);
@@ -1203,6 +1204,7 @@ static int kmem_cache_grow (kmem_cache_t * cachep, int flags)
 		SET_PAGE_CACHE(page, cachep);
 		SET_PAGE_SLAB(page, slabp);
 		SetPageSlab(page);
+		inc_page_state(nr_slab);
 		page++;
 	} while (--i);