On Wed, 18 Jan 2012 14:01:02 +0100 Michal Hocko <mhocko@xxxxxxx> wrote: > On Wed 18-01-12 08:55:58, KAMEZAWA Hiroyuki wrote: > > On Tue, 17 Jan 2012 16:16:20 +0100 > > Michal Hocko <mhocko@xxxxxxx> wrote: > > > > > On Fri 13-01-12 17:32:27, KAMEZAWA Hiroyuki wrote: > > > > > > > > From 788aebf15f3fa37940e0745cab72547e20683bf2 Mon Sep 17 00:00:00 2001 > > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > > > > Date: Thu, 12 Jan 2012 16:08:33 +0900 > > > > Subject: [PATCH 1/7] memcg: remove unnecessary check in mem_cgroup_update_page_stat() > > > > > > > > commit 10ea69f1182b removes move_lock_page_cgroup() in thp-split path. > > > > So, this PageTransHuge() check is unnecessary, too. > > > > > > I do not see commit like that in the tree. I guess you meant > > > memcg: make mem_cgroup_split_huge_fixup() more efficient which is not > > > merged yet, right? > > > > > > > This commit in the linux-next. > > Referring to commits from linux-next is tricky as it changes all the > time. I guess that the full commit subject should be sufficient. > > > > > Note: > > > > - considering when mem_cgroup_update_page_stat() is called, > > > > there will be no race between split_huge_page() and update_page_stat(). > > > > All required locks are held in higher level. > > > > > > We should never have THP page in this path in the first place. So why > > > not changing this to VM_BUG_ON(PageTransHuge). > > > > > > > Ying Han considers to support mlock stat. > > OK, got it. What about the following updated changelog instead? > > === > We do not have to check PageTransHuge in mem_cgroup_update_page_stat > and fallback into the locked accounting because both move charge and thp > split up are done with compound_lock so they cannot race. update vs. > move is protected by the mem_cgroup_stealed sufficiently. > > PageTransHuge pages shouldn't appear in this code path currently because > we are tracking only file pages at the moment but later we are planning > to track also other pages (e.g. mlocked ones). > === ok, will use this :) Thank you. -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>