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mm, thp: fix migration of PTE-mapped transparent huge pages

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We don't have native support of THP migration, so we have to split huge
page into small pages in order to migrate it to different node.  This
includes PTE-mapped huge pages.

I made mistake in refcounting patchset: we don't actually split
PTE-mapped huge page in queue_pages_pte_range(), if we step on head
page.

The result is that the head page is queued for migration, but none of
tail pages: putting head page on queue takes pin on the page and any
subsequent attempts of split_huge_pages() would fail and we skip queuing
tail pages.

unmap_and_move_huge_page() will eventually split the huge pages, but
only one of 512 pages would get migrated.

Let's fix the situation.

Fixes: 248db92da1 ("migrate_pages: try to split pages on queuing")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2016-03-09 14:08:30 -08:00 committed by Linus Torvalds
parent 30f471fd88
commit 0a2e280b6d
1 changed files with 1 additions and 1 deletions
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2
mm/mempolicy.c
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@ -532,7 +532,7 @@ retry:
nid = page_to_nid(page);
if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
continue;
if (PageTail(page) && PageAnon(page)) {
if (PageTransCompound(page) && PageAnon(page)) {
get_page(page);
pte_unmap_unlock(pte, ptl);
lock_page(page);