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Date: Fri, 26 Sep 2008 19:43:09 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"xemul@...nvz.org" <xemul@...nvz.org>,
Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Dave Hansen <haveblue@...ibm.com>, ryov@...inux.co.jp
Subject: Re: [PATCH 0/12] memcg updates v5
On Fri, 26 Sep 2008 14:24:55 +0900
Daisuke Nishimura <nishimura@....nes.nec.co.jp> wrote:
> Unfortunately, there remains some bugs yet...
>
Thank you for your patient good test!
I'm now testing following (and will do over-night test.)
In this an hour, this seems to work good.
(under your test which usually panics in 10-20min on my box.)
==
page_cgroup is not valid until pc->mem_cgroup is set to appropriate value.
There is a small race between Set-Used-Bit and Set-Proper-pc->mem_cgroup.
This patch tries to fix that by adding PCG_VALID bit
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
include/linux/page_cgroup.h | 3 +++
mm/memcontrol.c | 22 ++++++++++++++--------
2 files changed, 17 insertions(+), 8 deletions(-)
Index: mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
===================================================================
--- mmotm-2.6.27-rc7+.orig/include/linux/page_cgroup.h
+++ mmotm-2.6.27-rc7+/include/linux/page_cgroup.h
@@ -21,6 +21,7 @@ struct page_cgroup *lookup_page_cgroup(s
enum {
/* flags for mem_cgroup */
+ PCG_VALID, /* you can access this page cgroup */
PCG_LOCK, /* page cgroup is locked */
PCG_CACHE, /* charged as cache */
PCG_USED, /* this object is in use. */
@@ -50,6 +51,10 @@ static inline int TestSetPageCgroup##una
/* Cache flag is set only once (at allocation) */
TESTPCGFLAG(Cache, CACHE)
+TESTPCGFLAG(Valid, VALID)
+SETPCGFLAG(Valid, VALID)
+CLEARPCGFLAG(Valid, VALID)
+
TESTPCGFLAG(Used, USED)
CLEARPCGFLAG(Used, USED)
TESTSETPCGFLAG(Used, USED)
Index: mmotm-2.6.27-rc7+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memcontrol.c
+++ mmotm-2.6.27-rc7+/mm/memcontrol.c
@@ -340,7 +340,7 @@ void mem_cgroup_move_lists(struct page *
if (!trylock_page_cgroup(pc))
return;
- if (PageCgroupUsed(pc) && PageCgroupLRU(pc)) {
+ if (PageCgroupValid(pc) && PageCgroupLRU(pc)) {
mem = pc->mem_cgroup;
mz = page_cgroup_zoneinfo(pc);
spin_lock_irqsave(&mz->lru_lock, flags);
@@ -434,7 +434,7 @@ unsigned long mem_cgroup_isolate_pages(u
list_for_each_entry_safe_reverse(pc, tmp, src, lru) {
if (scan >= nr_to_scan)
break;
- if (unlikely(!PageCgroupUsed(pc)))
+ if (unlikely(!PageCgroupValid(pc)))
continue;
page = pc->page;
@@ -511,7 +511,7 @@ int mem_cgroup_move_account(struct page
return ret;
}
- if (!PageCgroupUsed(pc)) {
+ if (!PageCgroupValid(pc)) {
res_counter_uncharge(&to->res, PAGE_SIZE);
goto out;
}
@@ -580,6 +580,7 @@ __set_page_cgroup_lru(struct memcg_percp
unsigned long flags;
struct mem_cgroup_per_zone *mz, *prev_mz;
struct page_cgroup *pc;
+ struct mem_cgroup *mem;
int i, nr;
local_irq_save(flags);
@@ -589,6 +590,7 @@ __set_page_cgroup_lru(struct memcg_percp
for (i = nr - 1; i >= 0; i--) {
pc = mpv->vec[i];
+ mem = pc->mem_cgroup;
mz = page_cgroup_zoneinfo(pc);
if (prev_mz != mz) {
if (prev_mz)
@@ -596,9 +598,11 @@ __set_page_cgroup_lru(struct memcg_percp
prev_mz = mz;
spin_lock(&mz->lru_lock);
}
- if (PageCgroupUsed(pc) && !PageCgroupLRU(pc)) {
- SetPageCgroupLRU(pc);
- __mem_cgroup_add_list(mz, pc);
+ if (PageCgroupValid(pc) && !PageCgroupLRU(pc)) {
+ if (mem == pc->mem_cgroup) {
+ SetPageCgroupLRU(pc);
+ __mem_cgroup_add_list(mz, pc);
+ }
}
}
@@ -790,6 +794,7 @@ void mem_cgroup_commit_charge(struct pag
}
pc->mem_cgroup = mem;
+ SetPageCgroupValid(pc);
set_page_cgroup_lru(pc);
css_put(&mem->css);
preempt_enable();
@@ -928,6 +933,7 @@ __mem_cgroup_uncharge_common(struct page
return;
preempt_disable();
lock_page_cgroup(pc);
+ ClearPageCgroupValid(pc);
ClearPageCgroupUsed(pc);
mem = pc->mem_cgroup;
unlock_page_cgroup(pc);
@@ -970,7 +976,7 @@ int mem_cgroup_prepare_migration(struct
pc = lookup_page_cgroup(page);
lock_page_cgroup(pc);
- if (PageCgroupUsed(pc)) {
+ if (PageCgroupValid(pc)) {
mem = pc->mem_cgroup;
css_get(&mem->css);
if (PageCgroupCache(pc)) {
@@ -1086,7 +1092,7 @@ static void mem_cgroup_force_empty_list(
spin_lock_irqsave(&mz->lru_lock, flags);
list_for_each_entry_safe(pc, tmp, list, lru) {
page = pc->page;
- if (!PageCgroupUsed(pc))
+ if (!PageCgroupValid(pc))
continue;
/* For avoiding race with speculative page cache handling. */
if (!PageLRU(page) || !get_page_unless_zero(page))
--
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