Messages in this thread Patch in this message | | | Date | Fri, 11 Jun 2010 13:37:44 +0900 | From | Daisuke Nishimura <> | Subject | Re: [RFC][PATCH] memcg remove css_get/put per pages v2 |
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> @@ -2432,15 +2463,18 @@ mem_cgroup_uncharge_swapcache(struct pag > if (!swapout) /* this was a swap cache but the swap is unused ! */ > ctype = MEM_CGROUP_CHARGE_TYPE_DROP; > > - memcg = __mem_cgroup_uncharge_common(page, ctype); > + memcg = try_get_mem_cgroup_from_page(page); > + if (!memcg) > + return; > + > + __mem_cgroup_uncharge_common(page, ctype); > > /* record memcg information */ > - if (do_swap_account && swapout && memcg) { > + if (do_swap_account && swapout) { > swap_cgroup_record(ent, css_id(&memcg->css)); > mem_cgroup_get(memcg); > } > - if (swapout && memcg) > - css_put(&memcg->css); > + css_put(&memcg->css); > } > #endif > hmm, this change seems to cause a problem. I can see under flow of mem->memsw and "swap" field in memory.stat.
I think doing swap_cgroup_record() against mem_cgroup which is not returned by __mem_cgroup_uncharge_common() is a bad behavior.
How about doing like this ? We can safely access mem_cgroup while it has memory.usage, iow, before we call res_counter_uncharge(). After this change, it seems to work well.
--- mm/memcontrol.c | 22 +++++++++------------- 1 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6e7c1c9..2fae26f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2362,10 +2362,6 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) break; } - if (!mem_cgroup_is_root(mem)) - __do_uncharge(mem, ctype); - if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) - mem_cgroup_swap_statistics(mem, true); mem_cgroup_charge_statistics(mem, pc, false); ClearPageCgroupUsed(pc); @@ -2379,6 +2375,12 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) unlock_page_cgroup(pc); memcg_check_events(mem, page); + if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) { + mem_cgroup_swap_statistics(mem, true); + mem_cgroup_get(mem); + } + if (!mem_cgroup_is_root(mem)) + __do_uncharge(mem, ctype); return mem; @@ -2463,18 +2465,12 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) if (!swapout) /* this was a swap cache but the swap is unused ! */ ctype = MEM_CGROUP_CHARGE_TYPE_DROP; - memcg = try_get_mem_cgroup_from_page(page); - if (!memcg) - return; - - __mem_cgroup_uncharge_common(page, ctype); + memcg = __mem_cgroup_uncharge_common(page, ctype); /* record memcg information */ - if (do_swap_account && swapout) { + if (do_swap_account && swapout && memcg) + /* We've already done mem_cgroup_get() in uncharge_common(). */ swap_cgroup_record(ent, css_id(&memcg->css)); - mem_cgroup_get(memcg); - } - css_put(&memcg->css); } #endif
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