From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4755F041.4000605@google.com> Date: Tue, 04 Dec 2007 16:26:41 -0800 From: Ethan Solomita MIME-Version: 1.0 Subject: Re: page_referenced() and VM_LOCKED References: <473D1BC9.8050904@google.com> <20071116144641.f12fd610.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: KAMEZAWA Hiroyuki , linux-mm@kvack.org List-ID: Hugh Dickins wrote: > On Fri, 16 Nov 2007, KAMEZAWA Hiroyuki wrote: >> On Thu, 15 Nov 2007 20:25:45 -0800 >> Ethan Solomita wrote: >> >>> page_referenced_file() checks for the vma to be VM_LOCKED|VM_MAYSHARE >>> and adds returns 1. > > That's a case where it can deduce that the page is present and should > be treated as referenced, without even examining the page tables. > >>> We don't do the same in page_referenced_anon(). > > It cannot make that same deduction in the page_referenced_anon() case > (different vmas may well contain different COWs of some original page). Sorry to come back in with this so late -- if the vma is VM_MAYSHARE, would there be COWs of the original page? -- Ethan -- 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