[merged] mm-thp-flush-file-for-is_shmem-pagedirty-case-in-collapse_file.patch removed from -mm tree

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The patch titled
     Subject: mm/thp: flush file for !is_shmem PageDirty() case in collapse_file()
has been removed from the -mm tree.  Its filename was
     mm-thp-flush-file-for-is_shmem-pagedirty-case-in-collapse_file.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Song Liu <songliubraving@xxxxxx>
Subject: 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@xxxxxx
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/khugepaged.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/mm/khugepaged.c~mm-thp-flush-file-for-is_shmem-pagedirty-case-in-collapse_file
+++ a/mm/khugepaged.c
@@ -1602,6 +1602,24 @@ static void collapse_file(struct mm_stru
 					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);
_

Patches currently in -mm which might be from songliubraving@xxxxxx are





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