Re: [PATCH mm] stop c_p_a corrupting the pds

From: Hugh Dickins
Date: Tue Feb 05 2008 - 23:50:47 EST


On Tue, 5 Feb 2008, Valdis.Kletnieks@xxxxxx wrote:
> On Tue, 05 Feb 2008 22:27:21 GMT, Hugh Dickins said:
> > When change_page_attr splits a large page on x86_32 (without PAE), it is
> > currently corrupting every process's page directory: fix that by removing
> > the thinko which passes down a physical instead of a virtual address -
> > this version of the patch being the hotfix for 2.6.24-mm1.
> >
> > Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
>
> <snark>
> I *knew* there was a reason we should have had this patch series in -mm for a while.
> </snark>
>
> :)

Seriously, I do agree with you on that. It seems like the excitement
of making great changes has overtaken proper caution here.

Though I guess it was just coincidence that made it more debuggable
in my -mm kernel (which gave "bad pgd" errors after starting X), when
the -git kernel just crashed somehow in starting X. And I was lucky
to have CONFIG_VMSPLIT_2G_OPT on that machine, which placed the
corruption somewhere that soon got noticed.

Hugh
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