From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by kanga.kvack.org (Postfix) with ESMTP id C73E66B0038 for ; Mon, 15 Jun 2015 16:35:38 -0400 (EDT) Received: by wibdq8 with SMTP id dq8so90743755wib.1 for ; Mon, 15 Jun 2015 13:35:38 -0700 (PDT) Received: from mail-wg0-x233.google.com (mail-wg0-x233.google.com. [2a00:1450:400c:c00::233]) by mx.google.com with ESMTPS id q5si23931003wjw.143.2015.06.15.13.35.37 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Jun 2015 13:35:37 -0700 (PDT) Received: by wgv5 with SMTP id 5so77925644wgv.1 for ; Mon, 15 Jun 2015 13:35:36 -0700 (PDT) Date: Mon, 15 Jun 2015 22:35:32 +0200 From: Ingo Molnar Subject: Re: [PATCH 07/12] x86/virt/guest/xen: Remove use of pgd_list from the Xen guest code Message-ID: <20150615203532.GC13273@gmail.com> References: <1434188955-31397-1-git-send-email-mingo@kernel.org> <1434188955-31397-8-git-send-email-mingo@kernel.org> <1434359109.13744.14.camel@hellion.org.uk> <557EA944.9020504@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <557EA944.9020504@citrix.com> Sender: owner-linux-mm@kvack.org List-ID: To: David Vrabel Cc: Ian Campbell , Konrad Rzeszutek Wilk , Boris Ostrovsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org, Andy Lutomirski , Andrew Morton , Denys Vlasenko , Brian Gerst , Peter Zijlstra , Borislav Petkov , "H. Peter Anvin" , Linus Torvalds , Oleg Nesterov , Thomas Gleixner , Waiman Long * David Vrabel wrote: > On 15/06/15 10:05, Ian Campbell wrote: > > On Sat, 2015-06-13 at 11:49 +0200, Ingo Molnar wrote: > >> xen_mm_pin_all()/unpin_all() are used to implement full guest instance > >> suspend/restore. It's a stop-all method that needs to iterate through all > >> allocated pgds in the system to fix them up for Xen's use. > >> > >> This code uses pgd_list, probably because it was an easy interface. > >> > >> But we want to remove the pgd_list, so convert the code over to walk all > >> tasks in the system. This is an equivalent method. > > It is not equivalent because pgd_alloc() now populates entries in pgds that are > not visible to xen_mm_pin_all() (note how the original code adds the pgd to the > pgd_list in pgd_ctor() before calling pgd_prepopulate_pmd()). These newly > allocated page tables won't be correctly converted on suspend/resume and the new > process will die after resume. So how should the Xen logic be fixed for the new scheme? I can't say I can see through the paravirt complexity here. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org