Re: EFI kdump without acpi_rsdp

[Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 08/01/2013 09:27 PM, Vivek Goyal wrote:
> On Thu, Aug 01, 2013 at 10:12:25AM +0800, Dave Young wrote:
>> On 08/01/2013 04:55 AM, Vivek Goyal wrote:
>>> On Wed, Jul 31, 2013 at 04:48:00PM -0400, Vivek Goyal wrote:
>>>> On Wed, Jul 31, 2013 at 04:42:27PM -0400, Vivek Goyal wrote:
>>>>
>>>> [..]
>>>>> This system is behaving strangely. Yesterday I tried everything and it 
>>>>> did not work and today both 3.9 and 3.10 kernel seem to work (with
>>>>> acpi_rsdp=). I am upgrading kexec-tools now and will try again. If
>>>>> that works, then will try without acpi_rsdp.
>>>>>
>>>>> Well, with 3.10 kernel boots up device showsup but dump saving fails.
>>>>> Looks like makedumpfile bailed out.
>>>>>
>>>>> Hopefully upgrading kexec-tools will fix it.
>>>>
>>>> Well now OOM killer trigger while loading selinux policy. Red flags,
>>>> memory utilization of various components has gone up and even 128MB
>>>> does not seem to be sufficient.
>>>
>>> I upgraded from kexec-tools-2.0.3-71.fc19.x86_64 to
>>> kexec-tools-2.0.4-5.fc19.x86_64 and memory problem started happening. Have
>>> we done any significant change in kexec-tools which contributes to this.
>>
> 
> [ CC harald and initramfs list]
>> The main contribute is Harald enabled 98selinux. Chaowang said selinux
>> will use ~50M memory as the peak for load_policy. That is too much..
> 
> Hi Dave,
> 
> Have few questions. 
> 
> - I upgraded kexec-tools package and not dracut. So how did memory usage
>   go up.

It's strange, I don't think we have anything which use much memory.

> 
> - Were we not always loading selinux polity in initramfs. Otherwise I will
>   see relabeling happen when I boot back to first kernel. And In my
>   testing I did not see any relabeling happen. (I will make sure I was
>   not testing with selinux disabled).

Should always load selinux in initramfs unless rootfs mounting fails.

> 
> - 50MB for selinux policy sounds too much. In RHEL6 this usage was around
>   30MB and I remember in early fedora days it had dropped down to 18MB.
>   Daniel, Eric, does selinux policy load memory consumption has to be
>   this much. We reserve 128MB and 50MB is a huge chunk of that.
> 
>>
>> Ccing selinux peole Daniel and Eric. I wonder if there's a way we can
>> use in kdump initrd for minimum memory footprint. Because we will not
>> switch_root, so it will not influence the normal 1st kernel selinux.
> 
> I did not understand above statement Dave. Are you saying that we
> can save vmcore on root filesystem without loading selinux policy and
> still avoid relabeling in first kernel when it boots back. How?

Dracut will always mount rootfs so mostly we need not relabel in 1st
kernel because chroot load_policy in 2nd kernel will work unless rootfs
mounting fails.

I ever tested loading minimum policy in RHEL6, it use much less memory
than targeted policy.  Our target is simply label like file
/sysroot/var/crash/*/vmcore. I'm wondering if there's similar method we
can reduce memory usage in capture kernel.

> 
> Thanks
> Vivek
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-- 
Thanks
Dave