From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id 4C3D46B0069 for ; Tue, 10 Jul 2012 02:55:27 -0400 (EDT) Received: by yenr5 with SMTP id r5so13338162yen.14 for ; Mon, 09 Jul 2012 23:55:26 -0700 (PDT) Date: Tue, 10 Jul 2012 14:54:48 +0800 From: Wanpeng Li Subject: Re: [patch 08/11] mm: memcg: remove needless !mm fixup to init_mm when charging Message-ID: <20120710065448.GB6096@kernel> Reply-To: Wanpeng Li References: <1341449103-1986-1-git-send-email-hannes@cmpxchg.org> <1341449103-1986-9-git-send-email-hannes@cmpxchg.org> <20120709152058.GK4627@tiehlicka.suse.cz> <20120710061021.GA6096@kernel> <20120710062104.GA19223@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120710062104.GA19223@tiehlicka.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Johannes Weiner , Andrew Morton , KAMEZAWA Hiroyuki , Hugh Dickins , David Rientjes , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Wanpeng Li On Tue, Jul 10, 2012 at 08:21:04AM +0200, Michal Hocko wrote: >On Tue 10-07-12 14:10:21, Wanpeng Li wrote: >> On Mon, Jul 09, 2012 at 05:20:58PM +0200, Michal Hocko wrote: >> >On Thu 05-07-12 02:45:00, Johannes Weiner wrote: >> >> It does not matter to __mem_cgroup_try_charge() if the passed mm is >> >> NULL or init_mm, it will charge the root memcg in either case. >> >> You can also change the comment in __mem_cgroup_try_charge : >> >> "if so charge the init_mm" => "if so charge the root memcg" > >This is already in place: >" >If mm is NULL and the caller doesn't pass a valid memcg pointer, that is >treated as a charge to root_mem_cgroup. >" IIUC, if still keep comment "if so charge the init_mm" is not correct, since pages in pagecache aren't mapped into any processes' ptes, so mm is NULL, and these pages which in pagecache are not belong to init_mm, the comment should be changed. :-) >> >> >> >> >> Signed-off-by: Johannes Weiner >> > >> >Acked-by: Michal Hocko >> > >> >> --- >> >> mm/memcontrol.c | 5 ----- >> >> 1 files changed, 0 insertions(+), 5 deletions(-) >> >> >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> >> index 418b47d..6fe4101 100644 >> >> --- a/mm/memcontrol.c >> >> +++ b/mm/memcontrol.c >> >> @@ -2766,8 +2766,6 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm, >> >> ret = 0; >> >> return ret; >> >> charge_cur_mm: >> >> - if (unlikely(!mm)) >> >> - mm = &init_mm; >> >> ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true); >> >> if (ret == -EINTR) >> >> ret = 0; >> >> @@ -2832,9 +2830,6 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, >> >> if (PageCompound(page)) >> >> return 0; >> >> >> >> - if (unlikely(!mm)) >> >> - mm = &init_mm; >> >> - >> >> if (!PageSwapCache(page)) >> >> ret = mem_cgroup_charge_common(page, mm, gfp_mask, type); >> >> else { /* page is swapcache/shmem */ >> >> -- >> >> 1.7.7.6 >> >> >> > >> >-- >> >Michal Hocko >> >SUSE Labs >> >SUSE LINUX s.r.o. >> >Lihovarska 1060/12 >> >190 00 Praha 9 >> >Czech Republic >> >-- >> >To unsubscribe from this list: send the line "unsubscribe cgroups" in >> >the body of a message to majordomo@vger.kernel.org >> >More majordomo info at http://vger.kernel.org/majordomo-info.html > >-- >Michal Hocko >SUSE Labs >SUSE LINUX s.r.o. >Lihovarska 1060/12 >190 00 Praha 9 >Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org