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authorSong Liu <songliubraving@fb.com>2019-11-30 17:57:19 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 12:59:09 -0800
commit75f360696ce9d8ec8b253452b23b3e24c0689b4b (patch)
tree9e2c219ca30d2b4ef0c6f426e653518bb77422f1 /mm/khugepaged.c
parentf1fe80d4ae3396cf3665bd6dc77f4004c1c2e9f8 (diff)
mm/thp: flush file for !is_shmem PageDirty() case in collapse_file()
For non-shmem file THPs, khugepaged only collapses read only .text mapping (VM_DENYWRITE). These pages should not be dirty except the case where the file hasn't been flushed since first write. Call filemap_flush() in collapse_file() to accelerate the write back in such cases. Link: http://lkml.kernel.org/r/20191106060930.2571389-3-songliubraving@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
-rw-r--r--mm/khugepaged.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a8a57bebb5fa..b679908743cb 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1602,6 +1602,24 @@ static void collapse_file(struct mm_struct *mm,
result = SCAN_FAIL;
goto xa_unlocked;
}
+ } else if (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.
+ */
+ xas_unlock_irq(&xas);
+ filemap_flush(mapping);
+ result = SCAN_FAIL;
+ goto xa_unlocked;
} else if (trylock_page(page)) {
get_page(page);
xas_unlock_irq(&xas);