[RFC PATCH 2/2] arm: mm: Double logical invert for LPAE pte_write(), pte_dirty()

[catalin.marinas@arm.com (Catalin Marinas)]

On Thu, Feb 20, 2014 at 05:26:51PM +0000, Will Deacon wrote:
> On Fri, Feb 14, 2014 at 04:55:13PM +0000, Steve Capper wrote:
> > On LPAE, L_PTE_WRITE and L_PTE_DIRTY are in the upper 32-bits.
> > Unfortunately, results from pte_write() and pte_dirty() are downcast
> > to 32-bits by core code:
> >   o gather_stats
> >   o huge_pte_dirty
> >   o huge_pte_write
> >   o make_migration_entry
> > 
> > This patch adds a double logical invert to pte_write() and pte_dirty()
> > for LPAE to ensure that the lower 32-bits are set if true.
> 
> Yikes, this sounds like something we should put in -stable, no? If so,
> better make it patch 1 of this series.

That's a bug on arm64 as well since functions like gather_stats() take
an int as argument.

However, my preference is for a static inline function instead of "!!"
on arm64.

Steve, would you send a patch for arm64? If not, I can do it (with your
reported-by).

Thanks.

-- 
Catalin