On Tue, Oct 02, 2012 at 11:01:04PM +0100, Andrew Morton wrote:

On Tue,  2 Oct 2012 17:59:11 +0100
Will Deacon [off-list ref] wrote:

quoted

On x86 memory accesses to pages without the ACCESSED flag set result in the
ACCESSED flag being set automatically. With the ARM architecture a page access
fault is raised instead (and it will continue to be raised until the ACCESSED
flag is set for the appropriate PTE/PMD).

For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively
setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only
be called for a write fault.

This patch ensures that faults on transparent hugepages which do not result
in a CoW update the access flags for the faulting pmd.

Alas, the code you're altering has changed so much in linux-next that I
am reluctant to force this fix in there myself.  Can you please
redo/retest/resend?  You can do that on 3.7-rc1 if you like, then we
can feed this into -rc2.

No problem. I'll rebase the entire ARM series at -rc1 prior to posting
anyway, so this can be included in that lot.

quoted

--- a/mm/memory.c
+++ b/mm/memory.c

@@ -3524,7 +3524,8 @@ retry:
 
 		barrier();
 		if (pmd_trans_huge(orig_pmd)) {
-			if (flags & FAULT_FLAG_WRITE &&
+			int dirty = flags & FAULT_FLAG_WRITE;

`flags' is `unsigned int', so making `dirty' match that is nicer.

I'll fold that in with the above.

Cheers,

Will

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