From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id CEA976B0007 for ; Fri, 23 Feb 2018 18:25:55 -0500 (EST) Received: by mail-io0-f200.google.com with SMTP id 188so881166iou.14 for ; Fri, 23 Feb 2018 15:25:55 -0800 (PST) Received: from userp2130.oracle.com (userp2130.oracle.com. [156.151.31.86]) by mx.google.com with ESMTPS id s126si1887484itd.141.2018.02.23.15.25.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 Feb 2018 15:25:54 -0800 (PST) From: Pavel Tatashin Subject: [v1 0/1] Allow deferred page initialization for xen pv Date: Fri, 23 Feb 2018 18:25:37 -0500 Message-Id: <20180223232538.4314-1-pasha.tatashin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, pasha.tatashin@oracle.com, jgross@suse.com, akataria@vmware.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, boris.ostrovsky@oracle.com, akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz, luto@kernel.org, labbott@redhat.com, kirill.shutemov@linux.intel.com, bp@suse.de, minipli@googlemail.com, jinb.park7@gmail.com, dan.j.williams@intel.com, bhe@redhat.com, zhang.jia@linux.alibaba.com, mgorman@techsingularity.net, hannes@cmpxchg.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org >>From this discussion: https://www.spinics.net/lists/linux-mm/msg145604.html I investigated whether it is feasible to re-enable deferred page initialization on xen's para-vitalized domains. After studying the code, I found non-intrusive way to do just that. All we need to do is to assume that page-table's pages are pinned early in boot, which is always true, and add a new PV OP call to notify guests that boot allocator is finished, so we can set all the necessary fields in already initialized struct pages. I have tested this on my laptop with 64-bit kernel, but I would appreciate if someone could provide more xen testing. Apply against: linux-next. Enable the following configs: CONFIG_XEN_PV=y CONFIG_DEFERRED_STRUCT_PAGE_INIT=y The above two are needed to test deferred page initialization on PV Xen domains. If fix is applied correctly, dmesg should output line(s) like this during boot: [ 0.266180] node 0 initialised, 717570 pages in 36ms CONFIG_DEBUG_VM=y This is needed to poison struct page's memory, otherwise it would be all zero. CONFIG_DEBUG_VM_PGFLAGS=y Verifies that we do not access struct pages flags while memory is still poisoned (struct pages are not initialized yet). Pavel Tatashin (1): xen, mm: Allow deferred page initalization for xen pv domains arch/x86/include/asm/paravirt.h | 9 +++++++++ arch/x86/include/asm/paravirt_types.h | 3 +++ arch/x86/kernel/paravirt.c | 1 + arch/x86/mm/init_32.c | 1 + arch/x86/mm/init_64.c | 1 + arch/x86/xen/mmu_pv.c | 38 ++++++++++++++++++++++++----------- mm/page_alloc.c | 4 ---- 7 files changed, 41 insertions(+), 16 deletions(-) -- 2.16.2 -- 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