The patch titled
Subject: mmthp-recheck-each-page-before-collapsing-file-thp-v4
has been added to the -mm tree. Its filename is
mmthp-recheck-each-page-before-collapsing-file-thp-v4.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmthp-recheck-each-page-before-collapsing-file-thp-v4.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmthp-recheck-each-page-before-collapsing-file-thp-v4.patch
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------------------------------------------------------
From: Song Liu <songliubraving@xxxxxx>
Subject: mmthp-recheck-each-page-before-collapsing-file-thp-v4
Trigger filemap_flush() for PageDirty() case. This covers one-off
situation, where the file hasn't been flushed since first write.
Link: http://lkml.kernel.org/r/20191022191006.411277-1-songliubraving@xxxxxx
Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
--- a/mm/khugepaged.c~mmthp-recheck-each-page-before-collapsing-file-thp-v4
+++ a/mm/khugepaged.c
@@ -1636,11 +1636,20 @@ static void collapse_file(struct mm_stru
goto out_unlock;
}
- /*
- * khugepaged should not try to collapse dirty pages for
- * file THP. Show warning if this somehow happens.
- */
- if (WARN_ON_ONCE(!is_shmem && PageDirty(page))) {
+ if (!is_shmem && PageDirty(page)) {
+ /*
+ * khugepaged only works on read-only fd, so this
+ * page is dirty because it hasn't been flushed
+ * since first write. There won't be new dirty
+ * pages.
+ *
+ * Trigger async flush here and hope the writeback
+ * is done when khugepaged revisits this page.
+ *
+ * This is a one-off situation. We are not forcing
+ * writeback in loop.
+ */
+ filemap_flush(mapping);
result = SCAN_FAIL;
goto out_unlock;
}
_
Patches currently in -mm which might be from songliubraving@xxxxxx are
mmthp-recheck-each-page-before-collapsing-file-thp.patch
mmthp-recheck-each-page-before-collapsing-file-thp-v4.patch
