Re: [LKP] [x86/mm/ASLR] f47233c2d34: WARNING: CPU: 0 PID: 1 at arch/x86/mm/ioremap.c:63 __ioremap_check_ram+0x445/0x4a0()

From: Ingo Molnar
Date: Thu Feb 26 2015 - 06:12:59 EST



* Borislav Petkov <bp@xxxxxxx> wrote:

> thanks for the report.
>
> So, AFAICT, this is caused by ksysfs ioremapping struct
> setup_data for a short time so that it can count it and
> show it in /sys/kernel/boot_params/setup_data/*
>
> And, of course, the setup_data thing which we're using
> for kaslr param passing is RAM and ioremap complains.
>
> And currently I don't have a good idea how to fix it.
> Perhaps introduce an ioremap_* something which suppresses
> the warning as we're going to iounmap() right afterwards
> but that's ugly.

Why is it ioremap()-ed to begin with, why cannot the kernel
access its own data structure in RAM directly?

Thanks,

Ingo
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