[RFC PATCH 18/37] mm: enable speculative fault handling in do_numa_page()

[Michel Lespinasse]

Change handle_pte_fault() to allow speculative fault execution to proceed
through do_numa_page().

do_swap_page() does not implement speculative execution yet, so it
needs to abort with VM_FAULT_RETRY in that case.

Signed-off-by: Michel Lespinasse <mic...@lespinasse.org>
---
 mm/memory.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 78cc36749754..eea72bd78d06 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3346,6 +3346,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
        vm_fault_t ret = 0;
        void *shadow = NULL;
 
+       if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
+               pte_unmap(vmf->pte);
+               return VM_FAULT_RETRY;
+       }
+
        if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
                goto out;
 
@@ -4342,17 +4347,17 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
                        return do_fault(vmf);
        }
 
-       if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
-               pte_unmap(vmf->pte);
-               return VM_FAULT_RETRY;
-       }
-
        if (!pte_present(vmf->orig_pte))
                return do_swap_page(vmf);
 
        if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
                return do_numa_page(vmf);
 
+       if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
+               pte_unmap(vmf->pte);
+               return VM_FAULT_RETRY;
+       }
+
        vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
        spin_lock(vmf->ptl);
        entry = vmf->orig_pte;
-- 
2.20.1