Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757071AbdCXMFF (ORCPT ); Fri, 24 Mar 2017 08:05:05 -0400 Received: from mail-wm0-f51.google.com ([74.125.82.51]:37206 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbdCXMFC (ORCPT ); Fri, 24 Mar 2017 08:05:02 -0400 Date: Fri, 24 Mar 2017 15:04:58 +0300 From: "Kirill A. Shutemov" To: Xunlei Pang , Ingo Molnar Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, x86@kernel.org, "Kirill A. Shutemov" Subject: Re: [RFC PATCH] x86_64/mm/boot: Fix kernel_ident_mapping_init() failure for kexec Message-ID: <20170324120458.nw3fwpmdptjtj5qb@node.shutemov.name> References: <1489990291-2252-1-git-send-email-xlpang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1489990291-2252-1-git-send-email-xlpang@redhat.com> User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 934 Lines: 27 On Mon, Mar 20, 2017 at 02:11:31PM +0800, Xunlei Pang wrote: > I found that the kdump is broken on linux-4.11.0-rc2+ That's actually tip tree or linux-next. The problematic change is not in Linus' tree. > , probably > due to the 5level-paging feature that "#define p4d_present(p4d) 1", > as a result in ident_p4d_init(), it will go into ident_pud_init() > directly without allocating the new pud. > > Looks like this patch can make it work again. Okay, that's bisectability issue. Uncovered by splitting my patchset into parts. Could you check if applying "Part 2" of 5-level paging changes[1] would help you? Making the code work with both and would make it even uglier. Not sure if it makes sense to address it on its own if second part fixes the situation. [1] http://lkml.kernel.org/r/20170317185515.8636-1-kirill.shutemov@linux.intel.com -- Kirill A. Shutemov