mm: memcg: remove unused node/section info from pc->flags

To find the page corresponding to a certain page_cgroup, the pc->flags
encoded the node or section ID with the base array to compare the pc
pointer to.

Now that the per-memory cgroup LRU lists link page descriptors directly,
there is no longer any code that knows the struct page_cgroup of a PFN
but not the struct page.

[hughd@google.com: remove unused node/section info from pc->flags fix]
Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Ying Han <yinghan@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 52 deletions

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index f59405a8d752..f0559e049e00 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -11,12 +11,6 @@
 #include <linux/swapops.h>
 #include <linux/kmemleak.h>
 
-static void __meminit init_page_cgroup(struct page_cgroup *pc, unsigned long id)
-{
-        pc->flags = 0;
-        set_page_cgroup_array_id(pc, id);
-        pc->mem_cgroup = NULL;
-}
 static unsigned long total_usage;
 
 #if !defined(CONFIG_SPARSEMEM)
@@ -41,28 +35,13 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
         return base + offset;
 }
 
-struct page *lookup_cgroup_page(struct page_cgroup *pc)
-{
-        unsigned long pfn;
-        struct page *page;
-        pg_data_t *pgdat;
-
-        pgdat = NODE_DATA(page_cgroup_array_id(pc));
-        pfn = pc - pgdat->node_page_cgroup + pgdat->node_start_pfn;
-        page = pfn_to_page(pfn);
-        VM_BUG_ON(pc != lookup_page_cgroup(page));
-        return page;
-}
-
 static int __init alloc_node_page_cgroup(int nid)
 {
-        struct page_cgroup *base, *pc;
+        struct page_cgroup *base;
         unsigned long table_size;
-        unsigned long start_pfn, nr_pages, index;
+        unsigned long nr_pages;
 
-        start_pfn = NODE_DATA(nid)->node_start_pfn;
         nr_pages = NODE_DATA(nid)->node_spanned_pages;
-
         if (!nr_pages)
                 return 0;
 
@@ -72,10 +51,6 @@ static int __init alloc_node_page_cgroup(int nid)
                         table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
         if (!base)
                 return -ENOMEM;
-        for (index = 0; index < nr_pages; index++) {
-                pc = base + index;
-                init_page_cgroup(pc, nid);
-        }
         NODE_DATA(nid)->node_page_cgroup = base;
         total_usage += table_size;
         return 0;
@@ -116,23 +91,10 @@ struct page_cgroup *lookup_page_cgroup(struct page *page)
         return section->page_cgroup + pfn;
 }
 
-struct page *lookup_cgroup_page(struct page_cgroup *pc)
-{
-        struct mem_section *section;
-        struct page *page;
-        unsigned long nr;
-
-        nr = page_cgroup_array_id(pc);
-        section = __nr_to_section(nr);
-        page = pfn_to_page(pc - section->page_cgroup);
-        VM_BUG_ON(pc != lookup_page_cgroup(page));
-        return page;
-}
-
 static void *__meminit alloc_page_cgroup(size_t size, int nid)
 {
+        gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
         void *addr = NULL;
-        gfp_t flags = GFP_KERNEL | __GFP_NOWARN;
 
         addr = alloc_pages_exact_nid(nid, size, flags);
         if (addr) {
@@ -141,9 +103,9 @@ static void *__meminit alloc_page_cgroup(size_t size, int nid)
         }
 
         if (node_state(nid, N_HIGH_MEMORY))
-                addr = vmalloc_node(size, nid);
+                addr = vzalloc_node(size, nid);
         else
-                addr = vmalloc(size);
+                addr = vzalloc(size);
 
         return addr;
 }
@@ -166,14 +128,11 @@ static void free_page_cgroup(void *addr)
 
 static int __meminit init_section_page_cgroup(unsigned long pfn, int nid)
 {
-        struct page_cgroup *base, *pc;
         struct mem_section *section;
+        struct page_cgroup *base;
         unsigned long table_size;
-        unsigned long nr;
-        int index;
 
-        nr = pfn_to_section_nr(pfn);
-        section = __nr_to_section(nr);
+        section = __pfn_to_section(pfn);
 
         if (section->page_cgroup)
                 return 0;
@@ -193,10 +152,6 @@ static int __meminit init_section_page_cgroup(unsigned long pfn, int nid)
                 return -ENOMEM;
         }
 
-        for (index = 0; index < PAGES_PER_SECTION; index++) {
-                pc = base + index;
-                init_page_cgroup(pc, nr);
-        }
         /*
          * The passed "pfn" may not be aligned to SECTION.  For the calculation
          * we need to apply a mask.