From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx184.postini.com [74.125.245.184]) by kanga.kvack.org (Postfix) with SMTP id 1E0296B0070 for ; Thu, 23 Aug 2012 13:29:05 -0400 (EDT) Date: Thu, 23 Aug 2012 14:28:45 -0300 From: Rafael Aquini Subject: Re: [PATCH v8 1/5] mm: introduce a common interface for balloon pages mobility Message-ID: <20120823172844.GC10777@t510.redhat.com> References: <20120822000741.GI9027@redhat.com> <20120822011930.GA23753@t510.redhat.com> <20120822093317.GC10680@redhat.com> <20120823021903.GA23660@x61.redhat.com> <20120823100107.GA17409@redhat.com> <20120823121338.GA3062@t510.redhat.com> <20120823123432.GA25659@redhat.com> <20120823130606.GB3746@t510.redhat.com> <20120823135328.GB25709@redhat.com> <20120823162504.GA1522@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120823162504.GA1522@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Michael S. Tsirkin" Cc: "Paul E. McKenney" , Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell , Rik van Riel , Mel Gorman , Andi Kleen , Andrew Morton , Konrad Rzeszutek Wilk , Minchan Kim On Thu, Aug 23, 2012 at 07:25:05PM +0300, Michael S. Tsirkin wrote: > On Thu, Aug 23, 2012 at 04:53:28PM +0300, Michael S. Tsirkin wrote: > > Basically it was very simple: we assumed page->lru was never > > touched for an allocated page, so it's safe to use it for > > internal book-keeping by the driver. > > > > Now, this is not the case anymore, you add some logic in mm/ that might > > or might not touch page->lru depending on things like reference count. > > Another thought: would the issue go away if balloon used > page->private to link pages instead of LRU? > mm core could keep a reference on page to avoid it > being used while mm handles it (maybe it does already?). > I don't think so. That would be a lot more trikier and complex, IMHO. > If we do this, will not the only change to balloon be to tell mm that it > can use compaction for these pages when it allocates the page: using > some GPF flag or a new API? > What about keep a conter at virtio_balloon structure on how much pages are isolated from balloon's list and check it at leak time? if the counter gets > 0 than we can safely put leak_balloon() to wait until balloon page list gets completely refilled. I guess that is simple to get accomplished and potentially addresses all your concerns on this issue. Cheers! -- 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