From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-pd0-f174.google.com ([209.85.192.174]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Ug9tu-000673-Ir for kexec@lists.infradead.org; Sat, 25 May 2013 08:32:31 +0000 Received: by mail-pd0-f174.google.com with SMTP id 3so3145429pdj.33 for ; Sat, 25 May 2013 01:32:07 -0700 (PDT) Message-ID: <51A076FE.3060604@gmail.com> Date: Sat, 25 May 2013 16:31:58 +0800 From: Zhang Yanfei MIME-Version: 1.0 Subject: Re: [PATCH 0/2] kdump/mmap: Fix mmap of /proc/vmcore for s390 References: <1369400889-11064-1-git-send-email-holzheu@linux.vnet.ibm.com> <20130524143644.GD18218@redhat.com> <20130524170626.2ac06efe@holzheu> <20130524152849.GF18218@redhat.com> <87mwrkatgu.fsf@xmission.com> <51A006CF.90105@gmail.com> <87k3mnahkf.fsf@xmission.com> In-Reply-To: <87k3mnahkf.fsf@xmission.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: kexec@lists.infradead.org, Heiko Carstens , Jan Willeke , linux-kernel@vger.kernel.org, HATAYAMA Daisuke , Martin Schwidefsky , Andrew Morton , Michael Holzheu , Vivek Goyal 5LqOIDIwMTPlubQwNeaciDI15pelIDExOjAxLCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4g WmhhbmcgWWFuZmVpIDx6aGFuZ3lhbmZlaS55ZXNAZ21haWwuY29tPiB3cml0ZXM6Cj4gCj4+IEhl bGxvIEVyaWMsCj4+Cj4+PiBUaGUgZnVuY3Rpb24gY29weV9vbGRtZW1fcGFnZSBhbHNvIGNvbmNl cm5zIG1lLiAgSSBkb24ndCBoYXZlIGEgY2x1ZSB3aHkKPj4+IHdlIGR1cGxpY2F0ZSB0aGF0IGZ1 bmN0aW9uIG9uIGV2ZXJ5IGFyY2hpdGVjdXRyZSBpbiBhIHNsaWdodGx5IGRpZmZlcmVudAo+Pj4g Zm9ybS4gIFRoZXJlIHNob3VsZCBiZSBlbm91Z2ggYWJzdHJhY3Rpb25zIGluIHRoZSBrZXJuZWwg dG8gbWFrZSB0aGF0Cj4+PiB1bm5lY2Vzc2FyeS4gIEkgd291bGQgYmUgZ2xhZCB0byBzZWUgdGhh dCBmdW5jdGlvbiBnbywgYW5kIHJlbW92ZSB0aGUKPj4+IHBvc3NpYmlsaXR5IG9mIGNvbmZ1c2lv biB0aGF0IGhhcHBlbmVkIG9uIHMzOTAuCj4+Cj4+IFlvdSBtZWFuIHdlIHNob3VsZCBoYXZlIGEg Y29tbW9uIGNvcHlfb2xkbWVtX3BhZ2UgZm9yIGFsbCBhcmNoaXRlY3R1cmVzPyBBbmQKPj4ganVz dCBsaWtlIHZpdmVrIHNhaWQgYWJvdmUsIGZvciBzMzkwLCB3ZSBzaG91bGQgcHV0IHRoZSBzd2Fw IGluZm8gaW4gdGhlIGVsZgo+PiBoZWFkZXJzIGluc3RlYWQgb2YgZG9pbmcgdGhhdCBpbiBjb3B5 X29sZG1lbV9wYWdlLgo+IAo+IEV4YWN0bHkuCj4gCj4gVGhlIHVzZXIgc3BhY2UgY2hhbmdlIGlu IC9zYmluL2tleGVjIHNob3VsZCBldmVuIGJlIGJhY2t3YXJkcyBjb21wYXRpYmxlCj4gZm9yIHMz OTAuICBTbyBmaXhpbmcgL3NiaW4va2V4ZWMgc2hvdWxkIHByb2JhYmx5IGNvbWUgZmlyc3QuCj4g CgpJIGFtIGtpbmQgb2Ygbm90IHN1cmUgYWJvdXQgdGhlICJiYWNrd2FyZHMgY29tcGF0aWJsZSBm b3IgczM5MCIgeW91IG1lYW50LgoKRm9yIHMzOTAsIGlmIHdlIHB1dCBzd2FwIGluZm8gaW50byB0 aGUgZWxmIGhlYWRlciwgVGhpcyB3aWxsIGNoYW5nZSAvc2Jpbi9rZXhlYy4KQnV0IGF0IHRoaXMg cG9pbnQsIGNvcHlfb2xkbWVtX3BhZ2UgaXMgc3RpbGwgZG9pbmcgdGhlIHN3YXAgd2hlbiB3ZSB0 cnkgdG8gcmVhZAp0aGUgcGFnZXMgYW1vbmcgWzAgLSBPTERNRU1fU0laRV0gYW5kIFtPTERNRU1f QkFTRSAtIE9MRE1FTV9CQVNFICsgT0xETUVNX1NJWkVdLgpTbyByZW1vdmluZyB0aGUgc3dhcCBp biBjb3B5X29sZG1lbV9wYWdlIHNob3VsZCBiZSBkb25lIGF0IHRoZSBzYW1lIHRpbWUuCk5ldyBr ZXhlYyB3aXRoIG9sZCBrZXJuZWxzIHdvdWxkIGZhaWwgYW5kIG9sZCBrZXhlYyB3aXRoIG5ldyBr ZXJuZWxzIHdvdWxkIGZhaWwgdG9vLgoKU28gY291bGQgeW91IHBsZWFzZSBleHBsYWluIG1vcmUg YWJvdXQgdGhlICIiYmFja3dhcmRzIGNvbXBhdGlibGUiLiBBbmQgcGxlYXNlCmNvcnJlY3QgbWUg aWYgSSBhbSB3cm9uZy4KClRoYW5rcwpaaGFuZwoKCgpfX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fXwprZXhlYyBtYWlsaW5nIGxpc3QKa2V4ZWNAbGlzdHMuaW5m cmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2tl eGVjCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753584Ab3EYIcK (ORCPT ); Sat, 25 May 2013 04:32:10 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:38631 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752298Ab3EYIcI (ORCPT ); Sat, 25 May 2013 04:32:08 -0400 Message-ID: <51A076FE.3060604@gmail.com> Date: Sat, 25 May 2013 16:31:58 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.5) Gecko/20120607 Thunderbird/10.0.5 MIME-Version: 1.0 To: "Eric W. Biederman" CC: Vivek Goyal , Michael Holzheu , HATAYAMA Daisuke , Jan Willeke , Martin Schwidefsky , Heiko Carstens , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, Andrew Morton Subject: Re: [PATCH 0/2] kdump/mmap: Fix mmap of /proc/vmcore for s390 References: <1369400889-11064-1-git-send-email-holzheu@linux.vnet.ibm.com> <20130524143644.GD18218@redhat.com> <20130524170626.2ac06efe@holzheu> <20130524152849.GF18218@redhat.com> <87mwrkatgu.fsf@xmission.com> <51A006CF.90105@gmail.com> <87k3mnahkf.fsf@xmission.com> In-Reply-To: <87k3mnahkf.fsf@xmission.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2013年05月25日 11:01, Eric W. Biederman 写道: > Zhang Yanfei writes: > >> Hello Eric, >> >>> The function copy_oldmem_page also concerns me. I don't have a clue why >>> we duplicate that function on every architecutre in a slightly different >>> form. There should be enough abstractions in the kernel to make that >>> unnecessary. I would be glad to see that function go, and remove the >>> possibility of confusion that happened on s390. >> >> You mean we should have a common copy_oldmem_page for all architectures? And >> just like vivek said above, for s390, we should put the swap info in the elf >> headers instead of doing that in copy_oldmem_page. > > Exactly. > > The user space change in /sbin/kexec should even be backwards compatible > for s390. So fixing /sbin/kexec should probably come first. > I am kind of not sure about the "backwards compatible for s390" you meant. For s390, if we put swap info into the elf header, This will change /sbin/kexec. But at this point, copy_oldmem_page is still doing the swap when we try to read the pages among [0 - OLDMEM_SIZE] and [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]. So removing the swap in copy_oldmem_page should be done at the same time. New kexec with old kernels would fail and old kexec with new kernels would fail too. So could you please explain more about the ""backwards compatible". And please correct me if I am wrong. Thanks Zhang