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Date: Tue, 28 Apr 2009 09:19:02 +0900 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> To: nishimura@....nes.nec.co.jp Cc: Daisuke Nishimura <d-nishimura@....biglobe.ne.jp>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>, "hugh@...itas.com" <hugh@...itas.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] fix leak of swap accounting as stale swap cache under memcg On Mon, 27 Apr 2009 21:08:56 +0900 Daisuke Nishimura <d-nishimura@....biglobe.ne.jp> wrote: > > Index: mmotm-2.6.30-Apr24/mm/vmscan.c > > =================================================================== > > --- mmotm-2.6.30-Apr24.orig/mm/vmscan.c > > +++ mmotm-2.6.30-Apr24/mm/vmscan.c > > @@ -661,6 +661,9 @@ static unsigned long shrink_page_list(st > > if (PageAnon(page) && !PageSwapCache(page)) { > > if (!(sc->gfp_mask & __GFP_IO)) > > goto keep_locked; > > + /* avoid making more stale swap caches */ > > + if (memcg_stale_swap_congestion()) > > + goto keep_locked; > > if (!add_to_swap(page)) > > goto activate_locked; > > may_enter_fs = 1; > > > Well, as I mentioned before(http://marc.info/?l=linux-kernel&m=124066623510867&w=2), > this cannot avoid type-2(set !PageCgroupUsed by the owner process via > page_remove_rmap()->mem_cgroup_uncharge_page() before being added to swap cache). > If these swap caches go through shrink_page_list() without beeing freed > for some reason, these swap caches doesn't go back to memcg's LRU. > > Type-2 doesn't pressure memsw.usage, but you can see it by plotting > "grep SwapCached /proc/meminfo". > > And I don't think it's a good idea to add memcg_stale_swap_congestion() here. > This means less possibility to reclaim pages. > Hmm. maybe adding congestion_wait() ? > Do you dislike the patch I attached in the above mail ? > I doubt whether the patch covers all type-2 case. > If not, please merge it(I tested your prvious version with some fixes and > my patch, and it worked well). Or shall I send is as a separate patch > to fix type-2 after your patch(yours looks good to me for type-1)? > (to tell the truth, I want reuse memcg_free_unused_swapcache() in another patch) > > I'll consider again and post v3. But I'll go into a series of holidays, so, may not come back until May/6. Thanks, -Kame > Thanks, > Daisuke Nishimura. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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