From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8312 invoked by alias); 6 Apr 2009 17:43:22 -0000 Received: (qmail 8304 invoked by uid 22791); 6 Apr 2009 17:43:21 -0000 X-SWARE-Spam-Status: No, hits=-2.0 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 06 Apr 2009 17:43:11 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n36HhA6Z014597 for ; Mon, 6 Apr 2009 13:43:10 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n36HhEgd032038 for ; Mon, 6 Apr 2009 13:43:14 -0400 Received: from [10.16.2.46] (dhcp-100-2-46.bos.redhat.com [10.16.2.46]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id n36Hh9ow032510; Mon, 6 Apr 2009 13:43:10 -0400 Message-ID: <49DA3F85.7050302@redhat.com> Date: Mon, 06 Apr 2009 17:43:00 -0000 From: Masami Hiramatsu User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Mathieu Desnoyers CC: Ingo Molnar , Ananth N Mavinakayanahalli , LKML , systemtap-ml Subject: Re: [BUGFIX][PATCH -tip] x86: fix text_poke to handle highmem pages References: <49D76FFF.6020202@redhat.com> <20090404154230.GB2451@Krystal> <49D7A6DF.8080804@redhat.com> <49D7AF26.5030808@redhat.com> <49D82987.5090003@redhat.com> <49DA37CB.4020901@redhat.com> <20090406173238.GA31867@Krystal> In-Reply-To: <20090406173238.GA31867@Krystal> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2009-q2/txt/msg00138.txt.bz2 Mathieu Desnoyers wrote: > * Masami Hiramatsu (mhiramat@redhat.com) wrote: >> Fix a bug in text_poke to handle highmem pages, because module >> text pages are possible to be highmem pages on x86-32. >> In that case, since fixmap can't handle those pages, text_poke >> uses kmap_atomic. >> > > Hrm, can you remind me what would be the downside of using kmap_atomic > in every scenarios (highmem and non-highmem) then ? kmap_atomic can handle only highmem pages. If you passes lowmem pages, it returns just original vaddr of it. (because kmap is only for highmem support) > > I would try to avoid "special cases" as much as possible, because they > just make problems harder to reproduce. Actually, this bug is a special case because it happens only on PAE kernel. > > The idea would be to either add fixmap highmem support, or to simply use > kmap_atomic() for all cases until we add fixmap highmem support. > Thank you, -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division e-mail: mhiramat@redhat.com