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memcg: remove direct page_cgroup-to-page pointer

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In struct page_cgroup, we have a full word for flags but only a few are
reserved.  Use the remaining upper bits to encode, depending on
configuration, the node or the section, to enable page_cgroup-to-page
lookups without a direct pointer.

This saves a full word for every page in a system with memory cgroups
enabled.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner
2011-03-23 16:42:30 -07:00
committed by Linus Torvalds
parent 5564e88ba6
commit 6b3ae58efc
4 changed files with 117 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

91
mm/page_cgroup.c
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@ -11,12 +11,11 @@
#include <linux/swapops.h>
#include <linux/kmemleak.h>
static void __meminit
__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
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;
pc->page = pfn_to_page(pfn);
INIT_LIST_HEAD(&pc->lru);
}
static unsigned long total_usage;
@ -43,6 +42,19 @@ 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;
@ -63,7 +75,7 @@ static int __init alloc_node_page_cgroup(int nid)
return -ENOMEM;
for (index = 0; index < nr_pages; index++) {
pc = base + index;
__init_page_cgroup(pc, start_pfn + index);
init_page_cgroup(pc, nid);
}
NODE_DATA(nid)->node_page_cgroup = base;
total_usage += table_size;
@ -105,46 +117,53 @@ 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;
}
/* __alloc_bootmem...() is protected by !slab_available() */
static int __init_refok init_section_page_cgroup(unsigned long pfn)
{
struct mem_section *section = __pfn_to_section(pfn);
struct page_cgroup *base, *pc;
struct mem_section *section;
unsigned long table_size;
unsigned long nr;
int nid, index;
if (!section->page_cgroup) {
nid = page_to_nid(pfn_to_page(pfn));
table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
VM_BUG_ON(!slab_is_available());
if (node_state(nid, N_HIGH_MEMORY)) {
base = kmalloc_node(table_size,
GFP_KERNEL | __GFP_NOWARN, nid);
if (!base)
base = vmalloc_node(table_size, nid);
} else {
base = kmalloc(table_size, GFP_KERNEL | __GFP_NOWARN);
if (!base)
base = vmalloc(table_size);
}
/*
* The value stored in section->page_cgroup is (base - pfn)
* and it does not point to the memory block allocated above,
* causing kmemleak false positives.
*/
kmemleak_not_leak(base);
nr = pfn_to_section_nr(pfn);
section = __nr_to_section(nr);
if (section->page_cgroup)
return 0;
nid = page_to_nid(pfn_to_page(pfn));
table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
VM_BUG_ON(!slab_is_available());
if (node_state(nid, N_HIGH_MEMORY)) {
base = kmalloc_node(table_size,
GFP_KERNEL | __GFP_NOWARN, nid);
if (!base)
base = vmalloc_node(table_size, nid);
} else {
/*
* We don't have to allocate page_cgroup again, but
* address of memmap may be changed. So, we have to initialize
* again.
*/
base = section->page_cgroup + pfn;
table_size = 0;
/* check address of memmap is changed or not. */
if (base->page == pfn_to_page(pfn))
return 0;
base = kmalloc(table_size, GFP_KERNEL | __GFP_NOWARN);
if (!base)
base = vmalloc(table_size);
}
/*
* The value stored in section->page_cgroup is (base - pfn)
* and it does not point to the memory block allocated above,
* causing kmemleak false positives.
*/
kmemleak_not_leak(base);
if (!base) {
printk(KERN_ERR "page cgroup allocation failure\n");
@ -153,7 +172,7 @@ static int __init_refok init_section_page_cgroup(unsigned long pfn)
for (index = 0; index < PAGES_PER_SECTION; index++) {
pc = base + index;
__init_page_cgroup(pc, pfn + index);
init_page_cgroup(pc, nr);
}
section->page_cgroup = base - pfn;