Messages in this thread | | | Date | Tue, 28 Apr 2009 10:09:30 +0900 | From | nishimura@mxp ... | Subject | Re: [PATCH] fix leak of swap accounting as stale swap cache under memcg |
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> On Mon, 27 Apr 2009 21:08:56 +0900 > Daisuke Nishimura <d-nishimura@mtf.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() ? > I don't think no hook before add_to_swap() is needed.
>> Do you dislike the patch I attached in the above mail ? >> > I doubt whether the patch covers all type-2 case. > hmm, I didn't see any leak anymore when I tested the patch.
But because of machine time limit, I could only test for about 3 hours. (I had seen some leak at that point before applying my patch) I'll test for longer time if possible.
>> 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. > It's the same for me :)
Thanks, Daisuke Nishimura.
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