From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 18 Apr 2006 01:27:40 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 5/5] Swapless V2: Revise main migration logic In-Reply-To: <20060418170517.b46736d8.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20060413235406.15398.42233.sendpatchset@schroedinger.engr.sgi.com> <20060414113455.15fd5162.kamezawa.hiroyu@jp.fujitsu.com> <20060415090639.dde469e8.kamezawa.hiroyu@jp.fujitsu.com> <20060417091830.bca60006.kamezawa.hiroyu@jp.fujitsu.com> <20060418090439.3e2f0df4.kamezawa.hiroyu@jp.fujitsu.com> <20060418094212.3ece222f.kamezawa.hiroyu@jp.fujitsu.com> <20060418120016.14419e02.kamezawa.hiroyu@jp.fujitsu.com> <20060418123256.41eb56af.kamezawa.hiroyu@jp.fujitsu.com> <20060418170517.b46736d8.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: akpm@osdl.org, hugh@veritas.com, linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com, linux-mm@kvack.org, taka@valinux.co.jp, marcelo.tosatti@cyclades.com List-ID: On Tue, 18 Apr 2006, KAMEZAWA Hiroyuki wrote: > On Mon, 17 Apr 2006 23:58:41 -0700 (PDT) > Christoph Lameter wrote: > > > Hmmm... Good ideas. I think it could be much simpler like the following > > patch. > > > > However, the problem here is how to know that we really took the anon_vma > > lock and what to do about a page being unmmapped while migrating. This > > could cause the anon_vma not to be unlocked. > > > lock dependency here is page_lock(page) -> page's anon_vma->lock. > So, I guess anon_vma->lock cannot be unlocked by other threads > if we have page_lock(page). No the problem is to know if the lock was really taken. SWAP_AGAIN could mean that page_lock_anon_vma failed. Also the page may be freed while it is being processes. In that case remove_migration_ptes may not find the mapping and may not unlock the anon_vma. > > I guess we would need to have try_to_unmap return some state information. > What kind of information ? Information that indicates that the anon_vma lock was taken. -- 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