[RFC PATCH 2/2] ARMv7: Invalidate the TLB before freeing page tables

On Tue, 2011-02-15 at 11:32 +0000, Russell King - ARM Linux wrote:

On Tue, Feb 15, 2011 at 11:02:28AM +0000, Catalin Marinas wrote:

quoted

On Tue, 2011-02-15 at 10:31 +0000, Russell King - ARM Linux wrote:

quoted

We already have support for doing this, and Peter Zijlstra posted patches
to convert ARM to use a generic implementation of the TLB shootdown code.

http://marc.info/?l=linux-kernel&m=129604765010347&w=2

Does this patch solve your problem?

I don't think it does. Peter's patch moves the ARM TLB support to the
generic one which is a good clean-up, however it doesn't look like
anything is invalidating the TLB entry between pmd_clear() and
pte_free(), only after.

Can we please stop thinking "ooh, lets use generic code, that's good" ?
It's a rediculous attitude.  The reason we have our own version is because
the generic version is too heavy for our UP implementations and it doesn't
do what we need to do there.

I believe we should stick with our own version for UP, and switch over to
the generic version for SMP.

Whatever we do, the issue with A15 is valid for both UP and SMP since we
can get an interrupt which allocates a page previously hosting a pte but
before the TLB was invalidated.

I'll follow up on your patch as well.

-- 
Catalin