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SubjectRe: [PATCH 0/12] memcg updates v5
On Fri, 26 Sep 2008 19:43:09 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Fri, 26 Sep 2008 14:24:55 +0900
> Daisuke Nishimura <nishimura@mxp.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.)
>
This helps some, but causes other troubles. (But I know what it is.)
I'll add lock_page_cgroup() to charge side and see what happens.

Thanks,
-Kame



> ==
> 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@jp.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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