The patch titled
Subject: mm, thp: do not queue fully unmapped pages for deferred split
has been added to the -mm tree. Its filename is
mm-thp-do-not-queue-fully-unmapped-pages-for-deferred-split.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-do-not-queue-fully-unmapped-pages-for-deferred-split.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-do-not-queue-fully-unmapped-pages-for-deferred-split.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Subject: mm, thp: do not queue fully unmapped pages for deferred split
Adding fully unmapped pages into deferred split queue is not productive:
these pages are about to be freed or they are pinned and cannot be split
anyway.
Link: http://lkml.kernel.org/r/20190913091849.11151-1-kirill.shutemov@xxxxxxxxxxxxxxx
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/mm/rmap.c~mm-thp-do-not-queue-fully-unmapped-pages-for-deferred-split
+++ a/mm/rmap.c
@@ -1272,12 +1272,20 @@ static void page_remove_anon_compound_rm
if (TestClearPageDoubleMap(page)) {
/*
* Subpages can be mapped with PTEs too. Check how many of
- * themi are still mapped.
+ * them are still mapped.
*/
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
if (atomic_add_negative(-1, &page[i]._mapcount))
nr++;
}
+
+ /*
+ * Queue the page for deferred split if at least one small
+ * page of the compound page is unmapped, but at least one
+ * small page is still mapped.
+ */
+ if (nr && nr < HPAGE_PMD_NR)
+ deferred_split_huge_page(page);
} else {
nr = HPAGE_PMD_NR;
}
@@ -1285,10 +1293,8 @@ static void page_remove_anon_compound_rm
if (unlikely(PageMlocked(page)))
clear_page_mlock(page);
- if (nr) {
+ if (nr)
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
- deferred_split_huge_page(page);
- }
}
/**
_
Patches currently in -mm which might be from kirill@xxxxxxxxxxxxx are
mm-thp-do-not-queue-fully-unmapped-pages-for-deferred-split.patch
