From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753777Ab2APJEX (ORCPT ); Mon, 16 Jan 2012 04:04:23 -0500 Received: from terminus.zytor.com ([198.137.202.10]:45068 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753677Ab2APJEU (ORCPT ); Mon, 16 Jan 2012 04:04:20 -0500 Date: Mon, 16 Jan 2012 01:03:50 -0800 From: tip-bot for Tejun Heo Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, konrad.wilk@oracle.com, torvalds@linux-foundation.org, benh@kernel.crashing.org, akpm@linux-foundation.org, tj@kernel.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, benh@kernel.crashing.org, konrad.wilk@oracle.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, tj@kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20120113181412.GA11112@google.com> References: <20120113181412.GA11112@google.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/urgent] memblock: Fix alloc failure due to dumb underflow protection in memblock_find_in_range_node () Git-Commit-ID: 5d53cb27d849c899136c048ec84c940ac449494b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Mon, 16 Jan 2012 01:03:56 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5d53cb27d849c899136c048ec84c940ac449494b Gitweb: http://git.kernel.org/tip/5d53cb27d849c899136c048ec84c940ac449494b Author: Tejun Heo AuthorDate: Fri, 13 Jan 2012 10:14:12 -0800 Committer: Ingo Molnar CommitDate: Mon, 16 Jan 2012 08:38:06 +0100 memblock: Fix alloc failure due to dumb underflow protection in memblock_find_in_range_node() 7bd0b0f0da ("memblock: Reimplement memblock allocation using reverse free area iterator") implemented a simple top-down allocator using a reverse memblock iterator. To avoid underflow in the allocator loop, it simply raised the lower boundary to the requested size under the assumption that requested size would be far smaller than available memblocks. This causes early page table allocation failure under certain configurations in Xen. Fix it by checking for underflow directly instead of bumping up lower bound. Signed-off-by: Tejun Heo Reported-by: Konrad Rzeszutek Wilk Cc: rjw@sisk.pl Cc: xen-devel@lists.xensource.com Cc: Benjamin Herrenschmidt Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20120113181412.GA11112@google.com Signed-off-by: Ingo Molnar --- mm/memblock.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index 2f55f19..77b5f22 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -106,14 +106,17 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start, if (end == MEMBLOCK_ALLOC_ACCESSIBLE) end = memblock.current_limit; - /* adjust @start to avoid underflow and allocating the first page */ - start = max3(start, size, (phys_addr_t)PAGE_SIZE); + /* avoid allocating the first page */ + start = max_t(phys_addr_t, start, PAGE_SIZE); end = max(start, end); for_each_free_mem_range_reverse(i, nid, &this_start, &this_end, NULL) { this_start = clamp(this_start, start, end); this_end = clamp(this_end, start, end); + if (this_end < size) + continue; + cand = round_down(this_end - size, align); if (cand >= this_start) return cand;