Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.

H. Peter Anvin
2007-04-25T15:29:00Z

Andrew Morton wrote:

>
> This patch causes oopses after a minute or so running LTP's
>
> ./testcases/bin/growfiles -W gf16 -b -e 1 -i 0 -L 120 -u -g 4090 -T 100 -t 408990 -l -C 10 -c 1000 -S 10 -f Lgf02_
>
> on everyone's favoutite Vaio, configured with
> http://userweb.kernel.org/~akpm/config-sony.txt
>

*BLINK*

This patch only affects the initial page tables, which should have been
thrown out *way* long ago at this point.

Yet they seem to have stuck around. This is a very bad thing on many
levels, especially since we should have switched the kernel 1:1 area
over to PSE pages a long time ago.

> BUG: unable to handle kernel paging request at virtual address c084fa8c
> printing eip:
> c0174c46
> *pde = 0042a027
> *pte = 00000000

Touching a non-PSE page which is zero, and quite consistent with being a
remnant from the original page tables.

Methinks this has smoked out a bug in the initial page table setup which
probably has been a performance roadblock for quite some time.

-hpa