Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1606309

Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section

Show all headers | View raw

On 03/22/2017 at 12:30 PM, Dave Young wrote:
> On 03/21/17 at 10:18pm, Eric W. Biederman wrote:
>> Dave Young <dyoung@redhat.com> writes:
>>
>>> On 03/20/17 at 10:33pm, Eric W. Biederman wrote:
>>>> Xunlei Pang <xlpang@redhat.com> 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.

Regards,
Xunlei

>>>> 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.
> Yes, need careful review from s390 and maybe ppc64 especially about
> patch 2/3, better to have comments from IBM about s390 dump tool and ppc
> fadump. Added more cc.
>
> Thanks
> Dave
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Xunlei Pang <xlpang@redhat.com> - 2017-03-20 06:50 +0100
  [PATCH v3 2/3] powerpc/fadump: Use the correct VMCOREINFO_NOTE_SIZE for phdr Xunlei Pang <xlpang@redhat.com> - 2017-03-20 07:00 +0100
  [PATCH v3 3/3] kdump: Relocate vmcoreinfo to the crash memory range Xunlei Pang <xlpang@redhat.com> - 2017-03-20 07:00 +0100
  Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section ebiederm@xmission.com (Eric W. Biederman) - 2017-03-21 04:40 +0100
    Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Dave Young <dyoung@redhat.com> - 2017-03-22 04:10 +0100
      Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section ebiederm@xmission.com (Eric W. Biederman) - 2017-03-22 04:30 +0100
        Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Dave Young <dyoung@redhat.com> - 2017-03-22 05:40 +0100
          Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-22 10:40 +0100
            Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Hari Bathini <hbathini@linux.vnet.ibm.com> - 2017-03-22 13:20 +0100
          Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Hari Bathini <hbathini@linux.vnet.ibm.com> - 2017-03-22 12:50 +0100
          Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Michael Holzheu <holzheu@linux.vnet.ibm.com> - 2017-03-22 21:50 +0100
            Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-23 10:30 +0100
              Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Michael Holzheu <holzheu@linux.vnet.ibm.com> - 2017-03-23 18:50 +0100
                Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-24 12:10 +0100
    Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-22 10:00 +0100
      Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-22 10:20 +0100
      Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-03-22 10:30 +0100
  Re: [PATCH v3 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Petr Tesarik <ptesarik@suse.cz> - 2017-03-21 10:30 +0100

csiph-web