[patch 4/6] MMU notifier: invalidate_page callbacks using Linux rmaps

[Christoph Lameter]

These notifiers here use the Linux rmaps to perform the callbacks.
In order to walk the rmaps locks must be held. Callbacks can therefore
only operate in an atomic context.

Signed-off-by: Christoph Lameter <clameter@xxxxxxx>

---
 mm/rmap.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c	2008-01-25 14:27:01.000000000 -0800
+++ linux-2.6/mm/rmap.c	2008-01-25 14:27:04.000000000 -0800
@@ -288,6 +288,9 @@ static int page_referenced_one(struct pa
 	if (ptep_clear_flush_young(vma, address, pte))
 		referenced++;
 
+	if (mmu_notifier_age_page(mm, address))
+		referenced++;
+
 	/* Pretend the page is referenced if the task has the
 	   swap token and is in the middle of a page fault. */
 	if (mm != current->mm && has_swap_token(mm) &&
@@ -435,6 +438,7 @@ static int page_mkclean_one(struct page 
 
 		flush_cache_page(vma, address, pte_pfn(*pte));
 		entry = ptep_clear_flush(vma, address, pte);
+		mmu_notifier(invalidate_page, mm, address);
 		entry = pte_wrprotect(entry);
 		entry = pte_mkclean(entry);
 		set_pte_at(mm, address, pte, entry);
@@ -680,7 +684,8 @@ static int try_to_unmap_one(struct page 
 	 * skipped over this mm) then we should reactivate it.
 	 */
 	if (!migration && ((vma->vm_flags & VM_LOCKED) ||
-			(ptep_clear_flush_young(vma, address, pte)))) {
+			(ptep_clear_flush_young(vma, address, pte) ||
+				mmu_notifier_age_page(mm, address)))) {
 		ret = SWAP_FAIL;
 		goto out_unmap;
 	}
@@ -688,6 +693,7 @@ static int try_to_unmap_one(struct page 
 	/* Nuke the page table entry. */
 	flush_cache_page(vma, address, page_to_pfn(page));
 	pteval = ptep_clear_flush(vma, address, pte);
+	mmu_notifier(invalidate_page, mm, address);
 
 	/* Move the dirty bit to the physical page now the pte is gone. */
 	if (pte_dirty(pteval))
@@ -815,9 +821,13 @@ static void try_to_unmap_cluster(unsigne
 		if (ptep_clear_flush_young(vma, address, pte))
 			continue;
 
+		if (mmu_notifier_age_page(mm, address))
+			continue;
+
 		/* Nuke the page table entry. */
 		flush_cache_page(vma, address, pte_pfn(*pte));
 		pteval = ptep_clear_flush(vma, address, pte);
+		mmu_notifier(invalidate_page, mm, address);
 
 		/* If nonlinear, store the file page offset in the pte. */
 		if (page->index != linear_page_index(vma, address))

-- 
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