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 at redhat.com> writes: >> >>> On 03/20/17 at 10:33pm, Eric W. Biederman wrote: >>>> Xunlei Pang <xlpang at 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 at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec
