migrate_pages: try to split pages on queuing

[linux-2.6-block.git] / mm / mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5f7f9dace3546cf08256dd2674c54e25604448c6..973434eff9dcf2c521f2f589292f1a07a8c04d4b 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -489,14 +489,33 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
        struct page *page;
        struct queue_pages *qp = walk->private;
        unsigned long flags = qp->flags;
-       int nid;
+       int nid, ret;
        pte_t *pte;
        spinlock_t *ptl;
 
-       split_huge_pmd(vma, pmd, addr);
-       if (pmd_trans_unstable(pmd))
-               return 0;
+       if (pmd_trans_huge(*pmd)) {
+               ptl = pmd_lock(walk->mm, pmd);
+               if (pmd_trans_huge(*pmd)) {
+                       page = pmd_page(*pmd);
+                       if (is_huge_zero_page(page)) {
+                               spin_unlock(ptl);
+                               split_huge_pmd(vma, pmd, addr);
+                       } else {
+                               get_page(page);
+                               spin_unlock(ptl);
+                               lock_page(page);
+                               ret = split_huge_page(page);
+                               unlock_page(page);
+                               put_page(page);
+                               if (ret)
+                                       return 0;
+                       }
+               } else {
+                       spin_unlock(ptl);
+               }
+       }
 
+retry:
        pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
        for (; addr != end; pte++, addr += PAGE_SIZE) {
                if (!pte_present(*pte))
@@ -513,6 +532,21 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
                nid = page_to_nid(page);
                if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
                        continue;
+               if (PageTail(page) && PageAnon(page)) {
+                       get_page(page);
+                       pte_unmap_unlock(pte, ptl);
+                       lock_page(page);
+                       ret = split_huge_page(page);
+                       unlock_page(page);
+                       put_page(page);
+                       /* Failed to split -- skip. */
+                       if (ret) {
+                               pte = pte_offset_map_lock(walk->mm, pmd,
+                                               addr, &ptl);
+                               continue;
+                       }
+                       goto retry;
+               }
 
                if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
                        migrate_page_add(page, qp->pagelist, flags);