Return-Path: Message-Id: <20130703184049.892591791@goodmis.org> Date: Wed, 03 Jul 2013 14:39:29 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Aneesh Kumar K.V" , Hugh Dickins , Benjamin Herrenschmidt , Andrea Arcangeli , Andrew Morton Subject: [032/141] mm/THP: use pmd_populate() to update the pmd with pgtable_t pointer References: <20130703183857.307196999@goodmis.org> Content-Disposition: inline; filename=0032-mm-THP-use-pmd_populate-to-update-the-pmd-with-pgtab.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.6.11.6 stable review patch. If anyone has any objections, please let me know. ------------------ From: "Aneesh Kumar K.V" [ Upstream commit 7c3425123ddfdc5f48e7913ff59d908789712b18 ] We should not use set_pmd_at to update pmd_t with pgtable_t pointer. set_pmd_at is used to set pmd with huge pte entries and architectures like ppc64, clear few flags from the pte when saving a new entry. Without this change we observe bad pte errors like below on ppc64 with THP enabled. BUG: Bad page map in process ld mm=0xc000001ee39f4780 pte:7fc3f37848000001 pmd:c000001ec0000000 Signed-off-by: Aneesh Kumar K.V Cc: Hugh Dickins Cc: Benjamin Herrenschmidt Reviewed-by: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Steven Rostedt --- mm/huge_memory.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 141dbb6..29301d4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1954,7 +1954,12 @@ static void collapse_huge_page(struct mm_struct *mm, pte_unmap(pte); spin_lock(&mm->page_table_lock); BUG_ON(!pmd_none(*pmd)); - set_pmd_at(mm, address, pmd, _pmd); + /* + * We can only use set_pmd_at when establishing + * hugepmds and never for establishing regular pmds that + * points to regular pagetables. Use pmd_populate for that + */ + pmd_populate(mm, pmd, pmd_pgtable(_pmd)); spin_unlock(&mm->page_table_lock); anon_vma_unlock(vma->anon_vma); goto out; -- 1.7.10.4