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 5B2BA6B026A for ; Fri, 6 Jan 2017 10:46:06 -0500 (EST) Received: by mail-io0-f200.google.com with SMTP id j13so30495877iod.6 for ; Fri, 06 Jan 2017 07:46:06 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id m127si2454843itm.126.2017.01.06.07.46.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Jan 2017 07:46:05 -0800 (PST) From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= Subject: [HMM v15 06/16] mm/ZONE_DEVICE/x86: add support for un-addressable device memory Date: Fri, 6 Jan 2017 11:46:33 -0500 Message-Id: <1483721203-1678-7-git-send-email-jglisse@redhat.com> In-Reply-To: <1483721203-1678-1-git-send-email-jglisse@redhat.com> References: <1483721203-1678-1-git-send-email-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: John Hubbard , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" It does not need much, just skip populating kernel linear mapping for range of un-addressable device memory (it is pick so that there is no physical memory resource overlapping it). All the logic is in share mm code. Only support x86-64 as this feature doesn't make much sense with constrained virtual address space of 32bits architecture. Signed-off-by: JA(C)rA'me Glisse Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" --- arch/x86/mm/init_64.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 442ac86..6e7f613 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -654,7 +654,8 @@ static void update_end_of_memory_vars(u64 start, u64 size) int arch_add_memory(int nid, u64 start, u64 size, int flags) { const int supported_flags = MEMORY_DEVICE | - MEMORY_DEVICE_ALLOW_MIGRATE; + MEMORY_DEVICE_ALLOW_MIGRATE | + MEMORY_DEVICE_UNADDRESSABLE; struct pglist_data *pgdat = NODE_DATA(nid); struct zone *zone = pgdat->node_zones + zone_for_memory(nid, start, size, ZONE_NORMAL, @@ -669,7 +670,17 @@ int arch_add_memory(int nid, u64 start, u64 size, int flags) return -EINVAL; } - init_memory_mapping(start, start + size); + /* + * We get un-addressable memory when some one is adding a ZONE_DEVICE + * to have struct page for a device memory which is not accessible by + * the CPU so it is pointless to have a linear kernel mapping of such + * memory. + * + * Core mm should make sure it never set a pte pointing to such fake + * physical range. + */ + if (!(flags & MEMORY_DEVICE_UNADDRESSABLE)) + init_memory_mapping(start, start + size); ret = __add_pages(nid, zone, start_pfn, nr_pages); WARN_ON_ONCE(ret); @@ -968,7 +979,8 @@ kernel_physical_mapping_remove(unsigned long start, unsigned long end) int __ref arch_remove_memory(u64 start, u64 size, int flags) { const int supported_flags = MEMORY_DEVICE | - MEMORY_DEVICE_ALLOW_MIGRATE; + MEMORY_DEVICE_ALLOW_MIGRATE | + MEMORY_DEVICE_UNADDRESSABLE; unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; struct page *page = pfn_to_page(start_pfn); @@ -989,7 +1001,9 @@ int __ref arch_remove_memory(u64 start, u64 size, int flags) zone = page_zone(page); ret = __remove_pages(zone, start_pfn, nr_pages); WARN_ON_ONCE(ret); - kernel_physical_mapping_remove(start, start + size); + + if (!(flags & MEMORY_DEVICE_UNADDRESSABLE)) + kernel_physical_mapping_remove(start, start + size); return ret; } -- 2.4.3 -- 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