From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out02.mta.xmission.com ([166.70.13.232]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cqWsd-0002io-0P for kexec@lists.infradead.org; Wed, 22 Mar 2017 03:24:12 +0000 From: ebiederm@xmission.com (Eric W. Biederman) References: <1489989033-1179-1-git-send-email-xlpang@redhat.com> <87pohbz4lo.fsf@xmission.com> <20170322025536.GA4424@dhcp-128-65.nay.redhat.com> Date: Tue, 21 Mar 2017 22:18:30 -0500 In-Reply-To: <20170322025536.GA4424@dhcp-128-65.nay.redhat.com> (Dave Young's message of "Wed, 22 Mar 2017 10:55:36 +0800") Message-ID: <87pohaxam1.fsf@xmission.com> MIME-Version: 1.0 Subject: Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section 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" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dave Young Cc: Baoquan He , Xunlei Pang , Atsushi Kumagai , Petr Tesarik , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, kexec@lists.infradead.org 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. > >> >> As we are looking at reliability concerns removing CRASHTIME should make >> everything in vmcoreinfo a boot time constant. Which should simplify >> everything considerably. > > It is a nice improvement.. We also need to take a close look at what s390 is doing with vmcoreinfo. As apparently it is reading it in a different kind of crashdump process. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec