memcg: allocate all page_cgroup at boot
Allocate all page_cgroup at boot and remove page_cgroup poitner from
struct page. This patch adds an interface as
struct page_cgroup *lookup_page_cgroup(struct page*)
All FLATMEM/DISCONTIGMEM/SPARSEMEM and MEMORY_HOTPLUG is supported.
Remove page_cgroup pointer reduces the amount of memory by
- 4 bytes per PAGE_SIZE.
- 8 bytes per PAGE_SIZE
if memory controller is disabled. (even if configured.)
On usual 8GB x86-32 server, this saves 8MB of NORMAL_ZONE memory.
On my x86-64 server with 48GB of memory, this saves 96MB of memory.
I think this reduction makes sense.
By pre-allocation, kmalloc/kfree in charge/uncharge are removed.
This means
- we're not necessary to be afraid of kmalloc faiulre.
(this can happen because of gfp_mask type.)
- we can avoid calling kmalloc/kfree.
- we can avoid allocating tons of small objects which can be fragmented.
- we can know what amount of memory will be used for this extra-lru handling.
I added printk message as
"allocated %ld bytes of page_cgroup"
"please try cgroup_disable=memory option if you don't want"
maybe enough informative for users.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 031682e..d4a92b6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -33,11 +33,11 @@
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/mm_inline.h>
+#include <linux/page_cgroup.h>
#include <asm/uaccess.h>
struct cgroup_subsys mem_cgroup_subsys __read_mostly;
-static struct kmem_cache *page_cgroup_cache __read_mostly;
#define MEM_CGROUP_RECLAIM_RETRIES 5
/*
@@ -135,79 +135,6 @@
};
static struct mem_cgroup init_mem_cgroup;
-/*
- * We use the lower bit of the page->page_cgroup pointer as a bit spin
- * lock. We need to ensure that page->page_cgroup is at least two
- * byte aligned (based on comments from Nick Piggin). But since
- * bit_spin_lock doesn't actually set that lock bit in a non-debug
- * uniprocessor kernel, we should avoid setting it here too.
- */
-#define PAGE_CGROUP_LOCK_BIT 0x0
-#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
-#define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
-#else
-#define PAGE_CGROUP_LOCK 0x0
-#endif
-
-/*
- * A page_cgroup page is associated with every page descriptor. The
- * page_cgroup helps us identify information about the cgroup
- */
-struct page_cgroup {
- struct list_head lru; /* per cgroup LRU list */
- struct page *page;
- struct mem_cgroup *mem_cgroup;
- unsigned long flags;
-};
-
-enum {
- /* flags for mem_cgroup */
- PCG_CACHE, /* charged as cache */
- /* flags for LRU placement */
- PCG_ACTIVE, /* page is active in this cgroup */
- PCG_FILE, /* page is file system backed */
- PCG_UNEVICTABLE, /* page is unevictableable */
-};
-
-#define TESTPCGFLAG(uname, lname) \
-static inline int PageCgroup##uname(struct page_cgroup *pc) \
- { return test_bit(PCG_##lname, &pc->flags); }
-
-#define SETPCGFLAG(uname, lname) \
-static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
- { set_bit(PCG_##lname, &pc->flags); }
-
-#define CLEARPCGFLAG(uname, lname) \
-static inline void ClearPageCgroup##uname(struct page_cgroup *pc) \
- { clear_bit(PCG_##lname, &pc->flags); }
-
-
-/* Cache flag is set only once (at allocation) */
-TESTPCGFLAG(Cache, CACHE)
-
-/* LRU management flags (from global-lru definition) */
-TESTPCGFLAG(File, FILE)
-SETPCGFLAG(File, FILE)
-CLEARPCGFLAG(File, FILE)
-
-TESTPCGFLAG(Active, ACTIVE)
-SETPCGFLAG(Active, ACTIVE)
-CLEARPCGFLAG(Active, ACTIVE)
-
-TESTPCGFLAG(Unevictable, UNEVICTABLE)
-SETPCGFLAG(Unevictable, UNEVICTABLE)
-CLEARPCGFLAG(Unevictable, UNEVICTABLE)
-
-static int page_cgroup_nid(struct page_cgroup *pc)
-{
- return page_to_nid(pc->page);
-}
-
-static enum zone_type page_cgroup_zid(struct page_cgroup *pc)
-{
- return page_zonenum(pc->page);
-}
-
enum charge_type {
MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
MEM_CGROUP_CHARGE_TYPE_MAPPED,
@@ -216,12 +143,18 @@
NR_CHARGE_TYPE,
};
+/* only for here (for easy reading.) */
+#define PCGF_CACHE (1UL << PCG_CACHE)
+#define PCGF_USED (1UL << PCG_USED)
+#define PCGF_ACTIVE (1UL << PCG_ACTIVE)
+#define PCGF_LOCK (1UL << PCG_LOCK)
+#define PCGF_FILE (1UL << PCG_FILE)
static const unsigned long
pcg_default_flags[NR_CHARGE_TYPE] = {
- ((1 << PCG_CACHE) | (1 << PCG_FILE)),
- ((1 << PCG_ACTIVE)),
- ((1 << PCG_ACTIVE) | (1 << PCG_CACHE)),
- 0,
+ PCGF_CACHE | PCGF_FILE | PCGF_USED | PCGF_LOCK, /* File Cache */
+ PCGF_ACTIVE | PCGF_USED | PCGF_LOCK, /* Anon */
+ PCGF_ACTIVE | PCGF_CACHE | PCGF_USED | PCGF_LOCK, /* Shmem */
+ 0, /* FORCE */
};
/*
@@ -303,37 +236,6 @@
struct mem_cgroup, css);
}
-static inline int page_cgroup_locked(struct page *page)
-{
- return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
-{
- VM_BUG_ON(!page_cgroup_locked(page));
- page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
-}
-
-struct page_cgroup *page_get_page_cgroup(struct page *page)
-{
- return (struct page_cgroup *) (page->page_cgroup & ~PAGE_CGROUP_LOCK);
-}
-
-static void lock_page_cgroup(struct page *page)
-{
- bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static int try_lock_page_cgroup(struct page *page)
-{
- return bit_spin_trylock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
-static void unlock_page_cgroup(struct page *page)
-{
- bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
-}
-
static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
struct page_cgroup *pc)
{
@@ -436,17 +338,16 @@
* safely get to page_cgroup without it, so just try_lock it:
* mem_cgroup_isolate_pages allows for page left on wrong list.
*/
- if (!try_lock_page_cgroup(page))
+ pc = lookup_page_cgroup(page);
+ if (!trylock_page_cgroup(pc))
return;
-
- pc = page_get_page_cgroup(page);
- if (pc) {
+ if (pc && PageCgroupUsed(pc)) {
mz = page_cgroup_zoneinfo(pc);
spin_lock_irqsave(&mz->lru_lock, flags);
__mem_cgroup_move_lists(pc, lru);
spin_unlock_irqrestore(&mz->lru_lock, flags);
}
- unlock_page_cgroup(page);
+ unlock_page_cgroup(pc);
}
/*
@@ -533,6 +434,8 @@
list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
if (scan >= nr_to_scan)
break;
+ if (unlikely(!PageCgroupUsed(pc)))
+ continue;
page = pc->page;
if (unlikely(!PageLRU(page)))
@@ -576,26 +479,27 @@
{
struct mem_cgroup *mem;
struct page_cgroup *pc;
- unsigned long flags;
unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
struct mem_cgroup_per_zone *mz;
+ unsigned long flags;
- pc = kmem_cache_alloc(page_cgroup_cache, gfp_mask);
- if (unlikely(pc == NULL))
- goto err;
-
+ pc = lookup_page_cgroup(page);
+ /* can happen at boot */
+ if (unlikely(!pc))
+ return 0;
+ prefetchw(pc);
/*
* We always charge the cgroup the mm_struct belongs to.
* The mm_struct's mem_cgroup changes on task migration if the
* thread group leader migrates. It's possible that mm is not
* set, if so charge the init_mm (happens for pagecache usage).
*/
+
if (likely(!memcg)) {
rcu_read_lock();
mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!mem)) {
rcu_read_unlock();
- kmem_cache_free(page_cgroup_cache, pc);
return 0;
}
/*
@@ -631,36 +535,33 @@
}
}
+
+ lock_page_cgroup(pc);
+ if (unlikely(PageCgroupUsed(pc))) {
+ unlock_page_cgroup(pc);
+ res_counter_uncharge(&mem->res, PAGE_SIZE);
+ css_put(&mem->css);
+
+ goto done;
+ }
pc->mem_cgroup = mem;
- pc->page = page;
/*
* If a page is accounted as a page cache, insert to inactive list.
* If anon, insert to active list.
*/
pc->flags = pcg_default_flags[ctype];
- lock_page_cgroup(page);
- if (unlikely(page_get_page_cgroup(page))) {
- unlock_page_cgroup(page);
- res_counter_uncharge(&mem->res, PAGE_SIZE);
- css_put(&mem->css);
- kmem_cache_free(page_cgroup_cache, pc);
- goto done;
- }
- page_assign_page_cgroup(page, pc);
-
mz = page_cgroup_zoneinfo(pc);
+
spin_lock_irqsave(&mz->lru_lock, flags);
__mem_cgroup_add_list(mz, pc);
spin_unlock_irqrestore(&mz->lru_lock, flags);
+ unlock_page_cgroup(pc);
- unlock_page_cgroup(page);
done:
return 0;
out:
css_put(&mem->css);
- kmem_cache_free(page_cgroup_cache, pc);
-err:
return -ENOMEM;
}
@@ -668,7 +569,8 @@
{
if (mem_cgroup_subsys.disabled)
return 0;
-
+ if (PageCompound(page))
+ return 0;
/*
* If already mapped, we don't have to account.
* If page cache, page->mapping has address_space.
@@ -689,7 +591,8 @@
{
if (mem_cgroup_subsys.disabled)
return 0;
-
+ if (PageCompound(page))
+ return 0;
/*
* Corner case handling. This is called from add_to_page_cache()
* in usual. But some FS (shmem) precharges this page before calling it
@@ -702,15 +605,16 @@
if (!(gfp_mask & __GFP_WAIT)) {
struct page_cgroup *pc;
- lock_page_cgroup(page);
- pc = page_get_page_cgroup(page);
- if (pc) {
- VM_BUG_ON(pc->page != page);
- VM_BUG_ON(!pc->mem_cgroup);
- unlock_page_cgroup(page);
+
+ pc = lookup_page_cgroup(page);
+ if (!pc)
+ return 0;
+ lock_page_cgroup(pc);
+ if (PageCgroupUsed(pc)) {
+ unlock_page_cgroup(pc);
return 0;
}
- unlock_page_cgroup(page);
+ unlock_page_cgroup(pc);
}
if (unlikely(!mm))
@@ -741,37 +645,39 @@
/*
* Check if our page_cgroup is valid
*/
- lock_page_cgroup(page);
- pc = page_get_page_cgroup(page);
- if (unlikely(!pc))
- goto unlock;
+ pc = lookup_page_cgroup(page);
+ if (unlikely(!pc || !PageCgroupUsed(pc)))
+ return;
- VM_BUG_ON(pc->page != page);
-
- if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
- && ((PageCgroupCache(pc) || page_mapped(page))))
- goto unlock;
+ lock_page_cgroup(pc);
+ if ((ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED && page_mapped(page))
+ || !PageCgroupUsed(pc)) {
+ /* This happens at race in zap_pte_range() and do_swap_page()*/
+ unlock_page_cgroup(pc);
+ return;
+ }
+ ClearPageCgroupUsed(pc);
+ mem = pc->mem_cgroup;
mz = page_cgroup_zoneinfo(pc);
spin_lock_irqsave(&mz->lru_lock, flags);
__mem_cgroup_remove_list(mz, pc);
spin_unlock_irqrestore(&mz->lru_lock, flags);
+ unlock_page_cgroup(pc);
- page_assign_page_cgroup(page, NULL);
- unlock_page_cgroup(page);
-
- mem = pc->mem_cgroup;
res_counter_uncharge(&mem->res, PAGE_SIZE);
css_put(&mem->css);
- kmem_cache_free(page_cgroup_cache, pc);
return;
-unlock:
- unlock_page_cgroup(page);
}
void mem_cgroup_uncharge_page(struct page *page)
{
+ /* early check. */
+ if (page_mapped(page))
+ return;
+ if (page->mapping && !PageAnon(page))
+ return;
__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
}
@@ -795,9 +701,9 @@
if (mem_cgroup_subsys.disabled)
return 0;
- lock_page_cgroup(page);
- pc = page_get_page_cgroup(page);
- if (pc) {
+ pc = lookup_page_cgroup(page);
+ lock_page_cgroup(pc);
+ if (PageCgroupUsed(pc)) {
mem = pc->mem_cgroup;
css_get(&mem->css);
if (PageCgroupCache(pc)) {
@@ -807,7 +713,7 @@
ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
}
}
- unlock_page_cgroup(page);
+ unlock_page_cgroup(pc);
if (mem) {
ret = mem_cgroup_charge_common(newpage, NULL, GFP_KERNEL,
ctype, mem);
@@ -832,7 +738,7 @@
*/
if (!newpage->mapping)
__mem_cgroup_uncharge_common(newpage,
- MEM_CGROUP_CHARGE_TYPE_FORCE);
+ MEM_CGROUP_CHARGE_TYPE_FORCE);
else if (PageAnon(newpage))
mem_cgroup_uncharge_page(newpage);
}
@@ -918,6 +824,8 @@
while (!list_empty(list)) {
pc = list_entry(list->prev, struct page_cgroup, lru);
page = pc->page;
+ if (!PageCgroupUsed(pc))
+ break;
get_page(page);
spin_unlock_irqrestore(&mz->lru_lock, flags);
/*
@@ -932,8 +840,10 @@
count = FORCE_UNCHARGE_BATCH;
cond_resched();
}
- } else
- cond_resched();
+ } else {
+ spin_lock_irqsave(&mz->lru_lock, flags);
+ break;
+ }
spin_lock_irqsave(&mz->lru_lock, flags);
}
spin_unlock_irqrestore(&mz->lru_lock, flags);
@@ -957,6 +867,8 @@
while (mem->res.usage > 0) {
if (atomic_read(&mem->css.cgroup->count) > 0)
goto out;
+ /* This is for making all *used* pages to be on LRU. */
+ lru_add_drain_all();
for_each_node_state(node, N_POSSIBLE)
for (zid = 0; zid < MAX_NR_ZONES; zid++) {
struct mem_cgroup_per_zone *mz;
@@ -965,6 +877,7 @@
for_each_lru(l)
mem_cgroup_force_empty_list(mem, mz, l);
}
+ cond_resched();
}
ret = 0;
out:
@@ -1175,8 +1088,8 @@
int node;
if (unlikely((cont->parent) == NULL)) {
+ page_cgroup_init();
mem = &init_mem_cgroup;
- page_cgroup_cache = KMEM_CACHE(page_cgroup, SLAB_PANIC);
} else {
mem = mem_cgroup_alloc();
if (!mem)
