From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756864Ab0I0Xmj (ORCPT ); Mon, 27 Sep 2010 19:42:39 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:61363 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751410Ab0I0Xmi (ORCPT ); Mon, 27 Sep 2010 19:42:38 -0400 Message-ID: <4CA12BAB.1040308@kernel.org> Date: Mon, 27 Sep 2010 16:41:31 -0700 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100714 SUSE/3.0.6 Thunderbird/3.0.6 MIME-Version: 1.0 To: "H. Peter Anvin" CC: caiqian@redhat.com, Ingo Molnar , kexec , linux-kernel@vger.kernel.org Subject: Re: kexec load failure introduced by "x86, memblock: Replace e820_/_early string with memblock_" References: <632974489.2046131285586512527.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> <4CA11918.7050708@kernel.org> <4CA11FB7.2080101@zytor.com> <4CA126BE.7000609@kernel.org> <4CA1283C.9010105@zytor.com> <4CA12976.5060504@kernel.org> <4CA129EB.5000309@zytor.com> In-Reply-To: <4CA129EB.5000309@zytor.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/27/2010 04:34 PM, H. Peter Anvin wrote: > On 09/27/2010 04:32 PM, Yinghai Lu wrote: >> On 09/27/2010 04:26 PM, H. Peter Anvin wrote: >>> On 09/27/2010 04:20 PM, Yinghai Lu wrote: >>>> >>>> x86 own version for find_area? >>>> >>> >>> No, double no. >>> >>> Same kind of crap: overloading an interface with semantics it shouldn't >>> have. The right thing is to introduce a new interface with carries the >>> explicitly needed policy with it... e.g. memblock_find_in_range_lowest(). >>> >>> That interface would have the explicit semantics of returning the lowest >>> possible address, as opposed to any suitable address (which may change >>> if policy requirements change.) >>> >>> The other question is why does kexec need this in the first place? Is >>> this due to a design bug in kexec or is there some fundamental reason >>> for this? >> >> bzImage is used here. so need range below 4g. >> > > OK, so why don't you cap the range to 4 GiB and then pass that down to > the existing interface? That's different from "lowest possible address". but if later bzImage will use 64 entry and kexec honor it, or use 64bit vmlinux directly. and crashkernel=4096M, we could get failure again. maybe something like this, will give it a try, hope kexec doesn't have other limitation. [PATCH -v3] x86, memblock: Fix crashkernel allocation Cai Qian found crashkernel is broken with x86 memblock changes 1. crashkernel=128M@32M always reported that range is used, even first kernel is small no one use that range 2. always get following report when using "kexec -p" Could not find a free area of memory of a000 bytes... locate_hole failed The root cause is that generic memblock_find_in_range() will try to get range from top_down. But crashkernel do need from low and specified range. Let's limit the target range with rash_base + crash_size to make sure that We get range from bottom. -v3: don't use loop for find low one Reported-and-Bisected-by: CAI Qian Signed-off-by: Yinghai Lu --- arch/x86/kernel/setup.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) Index: linux-2.6/arch/x86/kernel/setup.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/setup.c +++ linux-2.6/arch/x86/kernel/setup.c @@ -518,17 +518,23 @@ static void __init reserve_crashkernel(v if (crash_base <= 0) { const unsigned long long alignment = 16<<20; /* 16M */ - crash_base = memblock_find_in_range(alignment, ULONG_MAX, crash_size, - alignment); + crash_base = memblock_find_in_range(alignment, 0xffffffff, + crash_size, alignment); + if (crash_base == MEMBLOCK_ERROR) { - pr_info("crashkernel reservation failed - No suitable area found.\n"); - return; + crash_base = memblock_find_in_range(alignment, + ULONG_MAX, crash_size, alignment); + + if (crash_base == MEMBLOCK_ERROR) { + pr_info("crashkernel reservation failed - No suitable area found.\n"); + return; + } } } else { unsigned long long start; - start = memblock_find_in_range(crash_base, ULONG_MAX, crash_size, - 1<<20); + start = memblock_find_in_range(crash_base, + crash_base + crash_size, crash_size, 1<<20); if (start != crash_base) { pr_info("crashkernel reservation failed - memory is in use.\n"); return;