Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 22/33] mm/THP: use pmd_populate() to update the pmd with pgtable_t pointer | Date | Wed, 5 Jun 2013 13:53:00 -0700 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
commit 7c3425123ddfdc5f48e7913ff59d908789712b18 upstream.
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 <aneesh.kumar@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Andrea Arcangeli <aarcange@redhat.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@linuxfoundation.org>
--- mm/huge_memory.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1893,7 +1893,12 @@ static void collapse_huge_page(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;
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