This patch fixes regression caused by patch "mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd" The patch makes pmd_trans_huge() check and "page = pmd_page(*pmd)" after __split_huge_pmd_locked(). It can never succeed, since the pmd already points to a page table. As result the page is never get munlocked. It causes crashes like this: http://lkml.kernel.org/r/5661FBB6.6050307@xxxxxxxxxx Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> --- mm/huge_memory.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 99f2a0ecb621..1a988d9b86ef 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3024,14 +3024,12 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, ptl = pmd_lock(mm, pmd); if (unlikely(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd))) goto out; - __split_huge_pmd_locked(vma, pmd, haddr, false); - - if (pmd_trans_huge(*pmd)) - page = pmd_page(*pmd); - if (page && PageMlocked(page)) + page = pmd_page(*pmd); + if (PageMlocked(page)) get_page(page); else page = NULL; + __split_huge_pmd_locked(vma, pmd, haddr, false); out: spin_unlock(ptl); mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); -- 2.6.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>