From e1e267c7928fe387e5e1cffeafb0de2d0473663a Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Mon, 6 Apr 2020 20:06:04 -0700 Subject: khugepaged: skip collapse if uffd-wp detected Don't collapse the huge PMD if there is any userfault write protected small PTEs. The problem is that the write protection is in small page granularity and there's no way to keep all these write protection information if the small pages are going to be merged into a huge PMD. The same thing needs to be considered for swap entries and migration entries. So do the check as well disregarding khugepaged_max_ptes_swap. Signed-off-by: Peter Xu Signed-off-by: Andrew Morton Reviewed-by: Jerome Glisse Reviewed-by: Mike Rapoport Cc: Andrea Arcangeli Cc: Bobby Powers Cc: Brian Geffon Cc: David Hildenbrand Cc: Denis Plotnikov Cc: "Dr . David Alan Gilbert" Cc: Hugh Dickins Cc: Johannes Weiner Cc: "Kirill A . Shutemov" Cc: Martin Cracauer Cc: Marty McFadden Cc: Maya Gokhale Cc: Mel Gorman Cc: Mike Kravetz Cc: Pavel Emelyanov Cc: Rik van Riel Cc: Shaohua Li Link: http://lkml.kernel.org/r/20200220163112.11409-12-peterx@redhat.com Signed-off-by: Linus Torvalds --- include/trace/events/huge_memory.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/trace') diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index d82a0f4e824d..70e32ff096ec 100644 --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -13,6 +13,7 @@ EM( SCAN_PMD_NULL, "pmd_null") \ EM( SCAN_EXCEED_NONE_PTE, "exceed_none_pte") \ EM( SCAN_PTE_NON_PRESENT, "pte_non_present") \ + EM( SCAN_PTE_UFFD_WP, "pte_uffd_wp") \ EM( SCAN_PAGE_RO, "no_writable_page") \ EM( SCAN_LACK_REFERENCED_PAGE, "lack_referenced_page") \ EM( SCAN_PAGE_NULL, "page_null") \ -- cgit v1.2.3