Re: [PATCH 6/6] mm: remove some update_mmu_cache() calls

Christoph Lameter
2006-06-22T16:37:39Z

On Thu, 22 Jun 2006, Hugh Dickins wrote:

> The answer I expect is that update_mmu_cache is essential there in
> do_wp_page (reuse case) and handle_pte_fault, on at least some if
> not all of those arches which implement it. That without those
> lines, they'll fault and refault endlessly, since the "MMU cache"
> has not been updated with the write permission.

Yes a likely scenario.

> But omitted from mprotect, since that's dealing with a batch of
> pages, perhaps none of which will be faulted in the near future:
> a waste of resources to update for all those entries.

So we intentially allow mprotect to be racy?

> But now I wonder, why does do_wp_page reuse case flush_cache_page?

Some arches may have virtual caches?