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=MAILING_LIST_MULTI,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 E7CD7C4321D for ; Thu, 23 Aug 2018 13:51:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94F20208DB for ; Thu, 23 Aug 2018 13:51:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 94F20208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731409AbeHWRVm (ORCPT ); Thu, 23 Aug 2018 13:21:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:53470 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730379AbeHWRVm (ORCPT ); Thu, 23 Aug 2018 13:21:42 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B85BDAF7A; Thu, 23 Aug 2018 13:51:52 +0000 (UTC) Date: Thu, 23 Aug 2018 15:51:51 +0200 From: Michal Hocko To: Tetsuo Handa Cc: Andrew Morton , linux-mm@kvack.org, xen-devel@lists.xenproject.org, LKML , Boris Ostrovsky , Juergen Gross Subject: Re: [PATCH] xen/gntdev: fix up blockable calls to mn_invl_range_start Message-ID: <20180823135151.GM29735@dhcp22.suse.cz> References: <20180823120707.10998-1-mhocko@kernel.org> <07c7ead4-334d-9b25-f588-25e9b46bbea0@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <07c7ead4-334d-9b25-f588-25e9b46bbea0@i-love.sakura.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 23-08-18 22:44:07, Tetsuo Handa wrote: > On 2018/08/23 21:07, Michal Hocko wrote: > > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > > index 57390c7666e5..e7d8bb1bee2a 100644 > > --- a/drivers/xen/gntdev.c > > +++ b/drivers/xen/gntdev.c > > @@ -519,21 +519,20 @@ static int mn_invl_range_start(struct mmu_notifier *mn, > > struct gntdev_grant_map *map; > > int ret = 0; > > > > - /* TODO do we really need a mutex here? */ > > if (blockable) > > mutex_lock(&priv->lock); > > else if (!mutex_trylock(&priv->lock)) > > return -EAGAIN; > > > > list_for_each_entry(map, &priv->maps, next) { > > - if (in_range(map, start, end)) { > > + if (!blockable && in_range(map, start, end)) { > > This still looks strange. Prior to 93065ac753e4, in_range() test was > inside unmap_if_in_range(). But this patch removes in_range() test > if blockable == true. That is, unmap_if_in_range() will unconditionally > unmap if blockable == true, which seems to be an unexpected change. You are right. I completely forgot I've removed in_range there. Does this look any better? diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index e7d8bb1bee2a..30f81004ea63 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -525,14 +525,20 @@ static int mn_invl_range_start(struct mmu_notifier *mn, return -EAGAIN; list_for_each_entry(map, &priv->maps, next) { - if (!blockable && in_range(map, start, end)) { + if (in_range(map, start, end)) { + if (blockable) + continue; + ret = -EAGAIN; goto out_unlock; } unmap_if_in_range(map, start, end); } list_for_each_entry(map, &priv->freeable_maps, next) { - if (!blockable && in_range(map, start, end)) { + if (in_range(map, start, end)) { + if (blockable) + continue; + ret = -EAGAIN; goto out_unlock; } -- Michal Hocko SUSE Labs