[RFC PATCH 17/37] mm: implement speculative handling in do_numa_page()

[Michel Lespinasse]

change do_numa_page() to use pte_spinlock() when locking the page table,
so that the mmap sequence counter will be validated in the speculative case.

Signed-off-by: Michel Lespinasse <mic...@lespinasse.org>
---
 mm/memory.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index a2c5bf29f989..78cc36749754 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4181,8 +4181,8 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
         * validation through pte_unmap_same(). It's of NUMA type but
         * the pfn may be screwed if the read is non atomic.
         */
-       vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
-       spin_lock(vmf->ptl);
+       if (!pte_spinlock(vmf))
+               return VM_FAULT_RETRY;
        if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
                pte_unmap_unlock(vmf->pte, vmf->ptl);
                goto out;
-- 
2.20.1