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Commit fd4a4663 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mm: fix hugepage migration 



2.6.37 added an unmap_and_move_huge_page() for memory failure recovery,
but its anon_vma handling was still based around the 2.6.35 conventions.
Update it to use page_lock_anon_vma, get_anon_vma, page_unlock_anon_vma,
drop_anon_vma in the same way as we're now changing unmap_and_move().

I don't particularly like to propose this for stable when I've not seen
its problems in practice nor tested the solution: but it's clearly out of
synch at present.

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: <stable@kernel.org> [2.6.37, 2.6.36]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1ce82b69

mm/migrate.c

+6 −17
Original line number Diff line number Diff line
@@ -827,7 +827,6 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, 
	int rc = 0;

	int *result = NULL;

	struct page *new_hpage = get_new_page(hpage, private, &result);

	int rcu_locked = 0;

	struct anon_vma *anon_vma = NULL;



	if (!new_hpage)
@@ -842,12 +841,10 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, 
	}



	if (PageAnon(hpage)) {

		rcu_read_lock();

		rcu_locked = 1;



		if (page_mapped(hpage)) {

			anon_vma = page_anon_vma(hpage);

			atomic_inc(&anon_vma->external_refcount);

		anon_vma = page_lock_anon_vma(hpage);

		if (anon_vma) {

			get_anon_vma(anon_vma);

			page_unlock_anon_vma(anon_vma);

		}

	}
@@ -859,16 +856,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, 
	if (rc)

		remove_migration_ptes(hpage, hpage);



	if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount,

					    &anon_vma->lock)) {

		int empty = list_empty(&anon_vma->head);

		spin_unlock(&anon_vma->lock);

		if (empty)

			anon_vma_free(anon_vma);

	}



	if (rcu_locked)

		rcu_read_unlock();

	if (anon_vma)

		drop_anon_vma(anon_vma);

out:

	unlock_page(hpage);