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Subject[RFC PATCH 18/37] mm: enable speculative fault handling in do_numa_page()
Date
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 <michel@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
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