+ mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch added to -mm tree

+ mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/khugepaged: collapse_shmem() remember to clear holes
has been added to the -mm tree.  Its filename is
     mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mm/khugepaged: collapse_shmem() remember to clear holes

Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp flags
khugepaged uses to allocate a huge page - in all common cases it would
just be a waste of effort - so collapse_shmem() must remember to clear out
any holes that it instantiates.

The obvious place to do so, where they are put into the page cache tree,
is not a good choice: because interrupts are disabled there.  Leave it
until further down, once success is assured, where the other pages are
copied (before setting PageUptodate).

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261525080.2275@eggly.anvils
Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/mm/khugepaged.c~mm-khugepaged-collapse_shmem-remember-to-clear-holes
+++ a/mm/khugepaged.c
@@ -1467,7 +1467,12 @@ xa_unlocked:
 		 * Replacing old pages with new one has succeeded, now we
 		 * need to copy the content and free the old pages.
 		 */
+		index = start;
 		list_for_each_entry_safe(page, tmp, &pagelist, lru) {
+			while (index < page->index) {
+				clear_highpage(new_page + (index % HPAGE_PMD_NR));
+				index++;
+			}
 			copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
 					page);
 			list_del(&page->lru);
@@ -1477,6 +1482,11 @@ xa_unlocked:
 			ClearPageActive(page);
 			ClearPageUnevictable(page);
 			put_page(page);
+			index++;
+		}
+		while (index < end) {
+			clear_highpage(new_page + (index % HPAGE_PMD_NR));
+			index++;
 		}
 
 		local_irq_disable();
_

Patches currently in -mm which might be from hughd@google.com are

mm-huge_memory-rename-freeze_page-to-unmap_page.patch
mm-huge_memory-splitting-set-mappingindex-before-unfreeze.patch
mm-huge_memory-fix-lockdep-complaint-on-32-bit-i_size_read.patch
mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch
mm-khugepaged-fix-crashes-due-to-misaccounted-holes.patch
mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch
mm-khugepaged-minor-reorderings-in-collapse_shmem.patch
mm-khugepaged-collapse_shmem-without-freezing-new_page.patch
mm-khugepaged-collapse_shmem-do-not-crash-on-compound.patch
mm-khugepaged-fix-the-xas_create_range-error-path.patch
mm-put_and_wait_on_page_locked-while-page-is-migrated.patch