From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
The pagewalker does not call most ops with NULL vma, those are all routed
to pte_hole instead.
Thus hmm_vma_fault() is only called with a NULL vma from
hmm_vma_walk_hole(), so hoist the check to there.
Now it is clear that snapshotting with no vma is a HMM_PFN_ERROR as
without a vma we have no path to call hmm_vma_fault().
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
---
mm/hmm.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c
index 14c33e1225866c..df0574061b37d3 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -83,9 +83,6 @@ static int hmm_vma_fault(unsigned long addr, unsigned long end,
WARN_ON_ONCE(!required_fault);
hmm_vma_walk->last = addr;
- if (!vma)
- return -EFAULT;
-
if ((required_fault & HMM_NEED_WRITE_FAULT) == HMM_NEED_WRITE_FAULT) {
if (!(vma->vm_flags & VM_WRITE))
return -EPERM;
@@ -175,6 +172,11 @@ static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
npages = (end - addr) >> PAGE_SHIFT;
pfns = &range->pfns[i];
required_fault = hmm_range_need_fault(hmm_vma_walk, pfns, npages, 0);
+ if (!walk->vma) {
+ if (required_fault)
+ return -EFAULT;
+ return hmm_pfns_fill(addr, end, range, HMM_PFN_ERROR);
+ }
if (required_fault)
return hmm_vma_fault(addr, end, required_fault, walk);
hmm_vma_walk->last = addr;
--
2.25.2
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