The patch titled
Subject: khugepaged: drain all LRU caches before scanning pages
has been added to the -mm tree. Its filename is
khugepaged-drain-all-lru-caches-before-scanning-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/khugepaged-drain-all-lru-caches-before-scanning-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/khugepaged-drain-all-lru-caches-before-scanning-pages.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: khugepaged: drain all LRU caches before scanning pages
Having a page in LRU add cache offsets page refcount and gives
false-negative on PageLRU(). It reduces collapse success rate.
Drain all LRU add caches before scanning. It happens relatively rare and
should not disturb the system too much.
Link: http://lkml.kernel.org/r/20200416160026.16538-4-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Tested-by: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/khugepaged.c~khugepaged-drain-all-lru-caches-before-scanning-pages
+++ a/mm/khugepaged.c
@@ -2078,6 +2078,8 @@ static void khugepaged_do_scan(void)
barrier(); /* write khugepaged_pages_to_scan to local stack */
+ lru_add_drain_all();
+
while (progress < pages) {
if (!khugepaged_prealloc_page(&hpage, &wait))
break;
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
khugepaged-add-self-test.patch
khugepaged-do-not-stop-collapse-if-less-than-half-ptes-are-referenced.patch
khugepaged-drain-all-lru-caches-before-scanning-pages.patch
khugepaged-drain-lru-add-pagevec-after-swapin.patch
khugepaged-allow-to-collapse-a-page-shared-across-fork.patch
khugepaged-allow-to-collapse-pte-mapped-compound-pages.patch
thp-change-cow-semantics-for-anon-thp.patch
khugepaged-introduce-max_ptes_shared-tunable.patch
