Not 32-bit ARM?

On Fri, Oct 12, 2018 at 6:35 PM, Joel Fernandes [off-list ref] wrote:

On Fri, Oct 12, 2018 at 11:18:36AM -0700, David Miller wrote:

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From: Joel Fernandes <redacted>

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Also, do we not flush the caches from any path when we munmap
address space?  We do call do_munmap on the old mapping from mremap
after moving to the new one.

Sparc makes sure that shared mapping have consistent colors.  Therefore
all that's left are private mappings and those will be initialized by
block stores to clear the page out or similar.

Also, when creating new mappings, we flush the D-cache when necessary
in update_mmu_cache().

We also maintain a bit in the page struct to track when a page which
was potentially written to on one cpu ends up mapped into another
address space and flush as necessary.

The cache is write-through, which simplifies the preconditions we have
to maintain.

Makes sense, thanks. For the moment I sent patches to enable this on arm64
and x86. We can enable it on sparc as well at a later time as it sounds it
could be a safe optimization to apply to that architecture as well.

thanks,

 - Joel