Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755796AbdGKNmM (ORCPT ); Tue, 11 Jul 2017 09:42:12 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:35945 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752577AbdGKNmL (ORCPT ); Tue, 11 Jul 2017 09:42:11 -0400 From: Michal Hocko To: Andrew Morton Cc: Cristopher Lameter , Johannes Weiner , Vlastimil Babka , , LKML , Michal Hocko Subject: [PATCH] vmemmap, memory_hotplug: fallback to base pages for vmmap Date: Tue, 11 Jul 2017 15:42:04 +0200 Message-Id: <20170711134204.20545-1-mhocko@kernel.org> X-Mailer: git-send-email 2.11.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1642 Lines: 45 From: Michal Hocko vmemmap_populate uses huge pages if the CPU supports them which is good and usually what we want. vmemmap_alloc_block will use the bootmem allocator in the early initialization so the allocation will most likely succeed. This is not the case for the memory hotplug though. Such an allocation can easily fail under memory pressure. Especially so when the kernel memory is restricted with movable_node parameter. There is no real reason to fail the vmemmap_populate when vmemmap_populate_hugepages fails though. We can still fallback to vmemmap_populate_basepages and use base pages. The performance will not be optimal but this is much better than failing the memory hot add. Signed-off-by: Michal Hocko --- arch/x86/mm/init_64.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 136422d7d539..e6e3c755b9cb 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1401,15 +1401,16 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start, int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) { struct vmem_altmap *altmap = to_vmem_altmap(start); - int err; + int err = -ENOMEM; if (boot_cpu_has(X86_FEATURE_PSE)) err = vmemmap_populate_hugepages(start, end, node, altmap); else if (altmap) { pr_err_once("%s: no cpu support for altmap allocations\n", __func__); - err = -ENOMEM; - } else + return err; + } + if (err) err = vmemmap_populate_basepages(start, end, node); if (!err) sync_global_pgds(start, end - 1); -- 2.11.0