Hi,
I'm working on a driver that relies on mmu notifications, and found that it is
lacking for huge pages.
From handle_mm_fault(),
If we take the normal page path, this is what happens:
handle_pte_fault -> do_wp_page -> ptep_clear_flush_notify ->
mmu_notifier_invalidate_page
If we're dealing with huge pages, this is what happens:
hugetlb_fault -> hugetlb_cow -> (no mmu notifiers)
Below is my patch, can anyone comment?
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4c9e6bb..96d9937 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2345,11 +2345,17 @@ retry_avoidcopy:
ptep = huge_pte_offset(mm, address & huge_page_mask(h));
if (likely(pte_same(huge_ptep_get(ptep), pte))) {
/* Break COW */
+ mmu_notifier_invalidate_range_start(mm,
+ address & huge_page_mask(h),
+ (address & huge_page_mask(h)) + huge_page_size(h));
huge_ptep_clear_flush(vma, address, ptep);
set_huge_pte_at(mm, address, ptep,
make_huge_pte(vma, new_page, 1));
/* Make the old page be freed below */
new_page = old_page;
+ mmu_notifier_invalidate_range_end(mm,
+ address & huge_page_mask(h),
+ (address & huge_page_mask(h)) + huge_page_size(h));
}
page_cache_release(new_page);
page_cache_release(old_page);
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>