Re: [1/2] 2.6.22-rc5: known regressions with patches

Ian McDonald
2007-06-20T23:02:54Z

On 6/21/07, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> And yes, sometimes debugging *does* change what it debugs. In timing, if
> nothing else, but also in the kinds of things you can do.

Totally agree.

> For example, we
> don't allow slab redzoning on data structures that have alignment
> restrictions not compatible with the redzoning, and I'd argue that this is
> more of the same: we just should not do DEBUG_RODATA if you expect to
> change read-only data.
>

Well the description for DEBUG_RODATA is:
Mark the kernel read-only data as write-protected in the pagetables,
in order to catch accidental (and incorrect) writes to such const data.

What we are doing with kprobes is neither accidental, nor incorrect.

> There's just no *point*.
>
> Linus
>
I understand your philosophical viewpoint here. Anyway it's no biggie
as can keep the patch out of tree if I want it... Another option is to
be able to enable and disable protecting read only data via a sysctl
but that seems even uglier.

Anyway I'll stop wasting your time now.

Ian
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