From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753055AbbJNInf (ORCPT ); Wed, 14 Oct 2015 04:43:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:60492 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752339AbbJNInc (ORCPT ); Wed, 14 Oct 2015 04:43:32 -0400 Date: Wed, 14 Oct 2015 10:43:28 +0200 From: Joerg Roedel To: Baoquan He Cc: akpm@linux-foundation.org, yinghai@kernel.org, dyoung@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, bp@suse.de, linux-kernel@vger.kernel.org, jerry_hoemann@hp.com Subject: Re: [PATCH] Do not reserve crashkernel high memory if crashkernel low memory reserving failed Message-ID: <20151014084328.GU10641@suse.de> References: <1443065091-28198-1-git-send-email-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1443065091-28198-1-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 On Thu, Sep 24, 2015 at 11:24:51AM +0800, 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. > > v4->v5: > Andrew suggested changing the content of failure message and taking > higher severity KERN_ERR. > > arch/x86/kernel/setup.c | 20 +++++++++++--------- > 1 file changed, 11 insertions(+), 9 deletions(-) Reviewed-by: Joerg Roedel The patch is also in SLES for some time now and was successfully tested there. Joerg