From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8E1FC282DD for ; Thu, 23 May 2019 19:40:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C87BF2133D for ; Thu, 23 May 2019 19:40:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390981AbfEWTkF (ORCPT ); Thu, 23 May 2019 15:40:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53712 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390281AbfEWTkD (ORCPT ); Thu, 23 May 2019 15:40:03 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 356F988E63; Thu, 23 May 2019 19:40:02 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.178]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4820A60BF3; Thu, 23 May 2019 19:40:01 +0000 (UTC) Date: Thu, 23 May 2019 15:39:59 -0400 From: Jerome Glisse To: Jason Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, Leon Romanovsky , Doug Ledford , Artemy Kovalyov , Moni Shoua , Mike Marciniszyn , Kaike Wan , Dennis Dalessandro Subject: Re: [PATCH v4 0/1] Use HMM for ODP v4 Message-ID: <20190523193959.GA5658@redhat.com> References: <20190522174852.GA23038@redhat.com> <20190522235737.GD15389@ziepe.ca> <20190523150432.GA5104@redhat.com> <20190523154149.GB12159@ziepe.ca> <20190523155207.GC5104@redhat.com> <20190523163429.GC12159@ziepe.ca> <20190523173302.GD5104@redhat.com> <20190523175546.GE12159@ziepe.ca> <20190523182458.GA3571@redhat.com> <20190523191038.GG12159@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190523191038.GG12159@ziepe.ca> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 23 May 2019 19:40:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 23, 2019 at 04:10:38PM -0300, Jason Gunthorpe wrote: > > On Thu, May 23, 2019 at 02:24:58PM -0400, Jerome Glisse wrote: > > I can not take mmap_sem in range_register, the READ_ONCE is fine and > > they are no race as we do take a reference on the hmm struct thus > > Of course there are use after free races with a READ_ONCE scheme, I > shouldn't have to explain this. Well i can not think of anything again here the mm->hmm can not change while driver is calling hmm_range_register() so if you want i can remove the READ_ONCE() this does not change anything. > If you cannot take the read mmap sem (why not?), then please use my > version and push the update to the driver through -mm.. Please see previous threads on why it was a failure. Cheers, Jérôme