From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933590AbbIVNvG (ORCPT ); Tue, 22 Sep 2015 09:51:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49442 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933313AbbIVNvE (ORCPT ); Tue, 22 Sep 2015 09:51:04 -0400 Date: Tue, 22 Sep 2015 21:50:59 +0800 From: Baoquan He To: akpm@linux-foundation.org, yinghai@kernel.org, dyoung@redhat.com, jroedel@suse.de, jerry_hoemann@hp.com Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, bp@suse.de, linux-kernel@vger.kernel.org Subject: Re: [Patch v4] Do not reserve crashkernel high memory if crashkernel low memory reserving failed Message-ID: <20150922135059.GA1844@dhcp-17-102.nay.redhat.com> References: <1442922494-5677-1-git-send-email-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442922494-5677-1-git-send-email-bhe@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add Jerry to CC list. On 09/22/15 at 07:48pm, Baoquan He wrote: > People reported that when allocating crashkernel memory using > ",high" and ",low" syntax, there were cases where the reservation > of the "high" portion succeeds, but the reservation of the "low" > portion fails. Then kexec can load kdump kernel successfully, but > the boot of kdump kernel fails as there's no low memory. This is > because allocation of low memory for kdump kernel can fail on large > systems for reasons. E.g it could be manually specified crashkernel > low memory is too large to find in memblock region. > > In this patch add return value for reserve_crashkernel_low. Then > try to reserve crashkernel low memory after crashkernel high memory > has been allocated. If crashkernel low memory reservation failed > free crashkernel high memory and return. User can take measures > when they found kdump kernel cann't be loaded successfully. > > Signed-off-by: Baoquan He > --- > v1->v2: > Boris commented that error value EINVAL is negative, should > use "return -EINVAL". > > v2->v3: > Yinghai pointed out that during memblock_reserve, we could double > the memblock reserve array. New memblock reserve could be overlapped > with range for crashkernel high. So we have to reserve crashkernel > high firstly, then free it if crashkernel low memory allocation > failed. > > v3->v4: > Dave suggested using "return -ENOMEM" when low memory reservation > failed and printing failure message anyway. > > arch/x86/kernel/setup.c | 19 ++++++++++--------- > 1 file changed, 10 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index fdb7f2a..e362f92 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -493,7 +493,7 @@ static void __init memblock_x86_reserve_range_setup_data(void) > # define CRASH_KERNEL_ADDR_HIGH_MAX MAXMEM > #endif > > -static void __init reserve_crashkernel_low(void) > +static int __init reserve_crashkernel_low(void) > { > #ifdef CONFIG_X86_64 > const unsigned long long alignment = 16<<20; /* 16M */ > @@ -522,17 +522,15 @@ static void __init reserve_crashkernel_low(void) > } else { > /* passed with crashkernel=0,low ? */ > if (!low_size) > - return; > + return 0; > } > > low_base = memblock_find_in_range(low_size, (1ULL<<32), > low_size, alignment); > > if (!low_base) { > - if (!auto_set) > - pr_info("crashkernel low reservation failed - No suitable area found.\n"); > - > - return; > + pr_info("crashkernel low reservation failed - No suitable area found.\n"); > + return -ENOMEM; > } > > memblock_reserve(low_base, low_size); > @@ -544,6 +542,7 @@ static void __init reserve_crashkernel_low(void) > crashk_low_res.end = low_base + low_size - 1; > insert_resource(&iomem_resource, &crashk_low_res); > #endif > + return 0; > } > > static void __init reserve_crashkernel(void) > @@ -595,6 +594,11 @@ static void __init reserve_crashkernel(void) > } > memblock_reserve(crash_base, crash_size); > > + if (crash_base >= (1ULL<<32) && reserve_crashkernel_low()) { > + memblock_free(crash_base, crash_size); > + return; > + } > + > printk(KERN_INFO "Reserving %ldMB of memory at %ldMB " > "for crashkernel (System RAM: %ldMB)\n", > (unsigned long)(crash_size >> 20), > @@ -604,9 +608,6 @@ static void __init reserve_crashkernel(void) > crashk_res.start = crash_base; > crashk_res.end = crash_base + crash_size - 1; > insert_resource(&iomem_resource, &crashk_res); > - > - if (crash_base >= (1ULL<<32)) > - reserve_crashkernel_low(); > } > #else > static void __init reserve_crashkernel(void) > -- > 2.1.0 >