Re: linux 2.6.27 kernel panic on x86 - please revert commit 3a85e770aa77e4f1a4096275c97b64c10cd7323e

[Jeff Chua]

On Wed, Oct 15, 2008 at 7:23 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Jeff Chua <jeff.chua.linux@xxxxxxxxx> wrote:
>
>> Commit 3a85e770aa77e4f1a4096275c97b64c10cd7323e broke linux boot on
>> x86 resulting in kernel panic. Here's the console output ...
>>
>> Net: Registered protocol family 17
>> Using IPI No-Shortcut mode
>> RAMDISK: Compressed image found at block 0
>> VFS: Mounted root (ext2 filesystem (readonly).
>> Freeing unsued kernel memory: 312k freed
>> init[1]: segfault at ffffe01c up b7f0dc28 sp bfc26628 error 5 in ld-2.7.90.so[b7f0b000+1c000]
>> Kernel panic - not syncing: Attempted to kill init!
>
> hm, ffffe01c is weird - VDSO on some ancient distro perhaps? Do you have
> CONFIG_COMPAT_VDSO=y enabled?
>
> if you have CONFIG_COMPAT_VDSO=y enabled but the read access still
> faults, then the question is, why is ffffe000 not mapped properly? The
> logic in arch/x86/vdso/vdso32-setup.c and map_compat_vdso() /
> arch_setup_additional_pages() seems correct and should result in the
> VDSO being mapped as user-readable.

Didn't realized that CONFIG_COMPAT_VDSO=y could cause this problem. I
had this set long time ago before upgrading to glibc-2.7

Unsetting CONFIG_COMPAT_VDSO solves the issue.

Thanks for your help, and sorry for the fault alarm. Did take a while
to trace it down to the commit.

Thanks,
Jeff.
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