From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cqfC1-0000H4-Ne for kexec@lists.infradead.org; Wed, 22 Mar 2017 12:16:47 +0000 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v2MCDrh4042716 for ; Wed, 22 Mar 2017 08:16:25 -0400 Received: from e23smtp07.au.ibm.com (e23smtp07.au.ibm.com [202.81.31.140]) by mx0a-001b2d01.pphosted.com with ESMTP id 29b9vn9p79-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 22 Mar 2017 08:16:24 -0400 Received: from localhost by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 22 Mar 2017 22:16:22 +1000 Received: from d23av05.au.ibm.com (d23av05.au.ibm.com [9.190.234.119]) by d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v2MCGCMM29425880 for ; Wed, 22 Mar 2017 23:16:20 +1100 Received: from d23av05.au.ibm.com (localhost [127.0.0.1]) by d23av05.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v2MCFmau001408 for ; Wed, 22 Mar 2017 23:15:48 +1100 Subject: Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section References: <1489989033-1179-1-git-send-email-xlpang@redhat.com> <87pohbz4lo.fsf@xmission.com> <20170322025536.GA4424@dhcp-128-65.nay.redhat.com> <87pohaxam1.fsf@xmission.com> <20170322043004.GB4424@dhcp-128-65.nay.redhat.com> <58D24543.5020700@redhat.com> From: Hari Bathini Date: Wed, 22 Mar 2017 17:45:28 +0530 MIME-Version: 1.0 In-Reply-To: <58D24543.5020700@redhat.com> Message-Id: <30b07524-0558-7edb-3b0f-ba5e4976ffb7@linux.vnet.ibm.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: xlpang@redhat.com, Dave Young , "Eric W. Biederman" Cc: Baoquan He , kexec@lists.infradead.org, Atsushi Kumagai , Petr Tesarik , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, holzheu@linux.vnet.ibm.com Hi Xunlei, On Wednesday 22 March 2017 03:04 PM, Xunlei Pang wrote: > On 03/22/2017 at 12:30 PM, Dave Young wrote: >> On 03/21/17 at 10:18pm, Eric W. Biederman wrote: >>> Dave Young writes: >>> >>>> On 03/20/17 at 10:33pm, Eric W. Biederman wrote: >>>>> Xunlei Pang writes: >>>>> >>>>>> As Eric said, >>>>>> "what we need to do is move the variable vmcoreinfo_note out >>>>>> of the kernel's .bss section. And modify the code to regenerate >>>>>> and keep this information in something like the control page. >>>>>> >>>>>> Definitely something like this needs a page all to itself, and ideally >>>>>> far away from any other kernel data structures. I clearly was not >>>>>> watching closely the data someone decided to keep this silly thing >>>>>> in the kernel's .bss section." >>>>>> >>>>>> This patch allocates extra pages for these vmcoreinfo_XXX variables, >>>>>> one advantage is that it enhances some safety of vmcoreinfo, because >>>>>> vmcoreinfo now is kept far away from other kernel data structures. >>>>> Can you preceed this patch with a patch that removes CRASHTIME from >>>>> vmcoreinfo? If someone actually cares we can add a separate note that holds >>>>> a 64bit crashtime in the per cpu notes. >>>> I think makedumpfile is using it, but I also vote to remove the >>>> CRASHTIME. It is better not to do this while crashing and a makedumpfile >>>> userspace patch is needed to drop the use of it. >>>> > By moving the CRASHTIME info to the cpu note of crashed cpu may be a good > way. In kdump kernel, notes of vmcore elfhdr will be merged into one big note > section, I don't know how makedumpfile or crash handle the big note section? > If they process the note in some order, breakage will definitely happen... > > There is also a fadump may be affected. > Would like to keep a tab of such change as fadump builds cpu notes differently and such change may have an impact on it considering it depends on the same tools - crash, makedumpfile.. Thanks Hari _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec