From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1SthSc-0000Gk-TT for kexec@lists.infradead.org; Tue, 24 Jul 2012 15:55:52 +0000 Message-ID: <1343145331.16290.45.camel@cr0> Subject: Re: [PATCH] x86: revert "x86: Fix S4 regression" From: Cong Wang Date: Tue, 24 Jul 2012 23:55:31 +0800 In-Reply-To: <500D340F.5080801@jp.fujitsu.com> References: <1339478463-31172-1-git-send-email-amwang@redhat.com> <5004D8BF.6050205@jp.fujitsu.com> <500D20A1.1030800@redhat.com> <500D340F.5080801@jp.fujitsu.com> Mime-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Takao Indoh Cc: yinghai.lu@oracle.com, tiwai@suse.de, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, rjw@sisk.pl, hpa@zytor.com, xiyou.wangcong@gmail.com, akpm@linux-foundation.org, dyoung@redhat.com On Mon, 2012-07-23 at 20:22 +0900, Takao Indoh wrote: > (2012/07/23 19:00), Dave Young wrote: > > On 07/17/2012 11:15 AM, Takao Indoh wrote: > > > >> Hi Cong, > >> > >> When I tested kdump with 3.5.0-rc6 kernel, I found a problem of kdump > >> kernel's panic in find_early_table_space(). > >> > >> init_memory_mapping: [mem 0x00000000-0x36ffafff] > >> Kernel panic - not syncing: Cannot find space for the kernel page tables > >> Pid: 0, comm: swapper Not tainted 3.5.0-rc6 #17 > >> Call Trace: > >> [] panic+0xb8/0x1c8 > >> [] ? printk+0x48/0x4a > >> [] init_memory_mapping+0x46c/0x530 > >> [] setup_arch+0x669/0xb0e > >> [] ? printk+0x48/0x4a > >> [] start_kernel+0x9b/0x34a > >> [] x86_64_start_reservations+0x131/0x136 > >> [] x86_64_start_kernel+0xed/0xf4 > >> > >> In find_early_table_space(), a kernel tries to find free area below 512M > >> for pgtable using memblock_find_in_range, but it fails because kdump > >> kernel does not have enough free space below 512M due to the memmap > >> restriction. This is the memmap option specified against kdump kernel > >> when crashkernel=128M. > >> > >> memmap=560K@64K memmap=130492K@770608K > >> > >> Only 560KB area is available and it is not sufficient for pgtable (it > >> seems that about 1.8MB area is needed for pgtable). This problem is > >> fixed by your revert patch. I hope this patch gets merged. > > > > > > I can reproduce this issue as well, probably related to some x86 mm init > > commits, this alloc failure does not happen with reverting below commits: > > > > bd2753b2dda7bb43c7468826de75f49c6a7e8965 > > 722bc6b16771ed80871e1fd81c86d3627dda2ac8 > Yeah, my result of bisect is as follows and at first I thought the > commit 722bc6 caused this regression. > > 722bc6b16771ed80871e1fd81c86d3627dda2ac8 is the first bad commit > commit 722bc6b16771ed80871e1fd81c86d3627dda2ac8 > Author: WANG Cong > Date: Mon Mar 5 15:05:13 2012 -0800 > > IIUC, this commit just fixes a bug of counting pgtable entries. As the > result, another problem came up to the surface. In the case of my > machine(16GB memory), before applying 722bc6, find_early_table_space() > requests about 12KB free area and it can be got from 560K@64K area > luckily. I think the size find_early_table_space() requests was a bug. > After the bug is fixed by the commit 722bc6, find_early_table_space() > requires 1.8MB area and it fails as I wrote. Thanks for tracking this, Takao! I bet you are using x86_64 not x86 PAE? If so, could you try this patch https://patchwork.kernel.org/patch/1195751/ ? I already reviewed it. Sorry for the trouble! _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec