From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 19 Apr 2006 12:39:11 +0900 From: KAMEZAWA Hiroyuki Subject: Re: Read/Write migration entries: Implement correct behavior in copy_one_pte Message-Id: <20060419123911.3bd22ab3.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20060419095044.d7333b21.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: hugh@veritas.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@osdl.org List-ID: On Tue, 18 Apr 2006 18:27:28 -0700 (PDT) Christoph Lameter wrote: > On Wed, 19 Apr 2006, KAMEZAWA Hiroyuki wrote: > > > > Note that this is again only a partial solution. mprotect() also has the > > > potential of changing the write status to read. > > yes. in change_pte_range(). > > > > Note: > > fork() and mprotect() both requires mm->mmap_sem. > > So both of them is not problem when migration holds mm->mmap_sem. > > If we does lazy migration or memory hot removing or allows migration from > > another process, this will be problem. > > Oh. We already allow migration from another process since the page may > be mapped by multiple mm's. Page migration will then replace the ptes in > *all* mm_structs that map this page with migration entries. > > So we need a fix here. > Ah.....yes. sorry. In my understanding (and grep), read/write protection for anon pages can be changed under - fork() - mprotect() all are known. BTW, do we manage page table under move_vma() in right way ? -Kame -- 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