From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Hering Subject: Re: [PATCH] x86/mm: Improve ring management for memory events. Do not lose guest events Date: Fri, 13 Jan 2012 20:57:06 +0100 Message-ID: <20120113195706.GA26566@aepfle.de> References: <20120113095022.GA18130@aepfle.de> <873a666b95bbe7e50992fb1059bc2220.squirrel@webmail.lagarcavilla.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <873a666b95bbe7e50992fb1059bc2220.squirrel@webmail.lagarcavilla.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Andres Lagar-Cavilla Cc: andres@gridcentric.ca, xen-devel@lists.xensource.com, tim@xen.org, adin@gridcentric.ca List-Id: xen-devel@lists.xenproject.org On Fri, Jan 13, Andres Lagar-Cavilla wrote: > > p2m_mem_paging_drop_page() should remain void because the caller has > > already done its work, making it not restartable. Also it is only called > > when a gfn is in paging state, which I'm sure can not happen without a > > ring. > > Well, the rationale is that returning an error code can only help, should > new error conditions arise. Keep in mind that the pager and the ring can > disappear at any time, so ENOSYS can still happen. The ring should rather not disappear at all until ->paged_pages drops to zero. Unless the goal is a restartable pager, XEN_DOMCTL_MEM_EVENT_OP_PAGING_DISABLE should return -EBUSY when ->pages_pages is not zero. Then the checks in drop_page and populate can be relaxed. > I'll refresh and add your signed-off-by to cover the portions of the work > that originate from your end, is that ok? I havent finish the review yet, have to check how it may work with wait queues in gfn_to_mfn*. Olaf