| Date | Tue, 15 Feb 2011 16:13:01 -0800 | From | Greg KH <> | Subject | [124/272] mm: fix hugepage migration |
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2.6.37-stable review patch. If anyone has any objections, please let us know.
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From: Hugh Dickins <hughd@google.com>
commit fd4a4663db293bfd5dc20fb4113977f62895e550 upstream.
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: Hugh 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/migrate.c | 23 ++++++----------------- 1 file changed, 6 insertions(+), 17 deletions(-)
--- a/mm/migrate.c +++ b/mm/migrate.c @@ -805,7 +805,6 @@ static int unmap_and_move_huge_page(new_ 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) @@ -820,12 +819,10 @@ static int unmap_and_move_huge_page(new_ } 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); } } @@ -837,16 +834,8 @@ static int unmap_and_move_huge_page(new_ 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);
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