Commit 2af8ff29 authored Nov 30, 2018 by Hugh Dickins Committed by Linus Torvalds Nov 30, 2018

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: f3f0e1d2 ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent aaa52e34

mm/khugepaged.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -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();

Admin message