From: Jason Gunthorpe jgg@mellanox.com
The pagewalker does not call most ops with NULL vma, those are all routed to hmm_vma_walk_hole() via ops->pte_hole instead.
Thus hmm_vma_fault() is only called with a NULL vma from hmm_vma_walk_hole(), so hoist the NULL vma 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().
Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Jason Gunthorpe jgg@mellanox.com --- mm/hmm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c index e875d9ef0968fd..31d0f68689c32b 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) { if (!(vma->vm_flags & VM_WRITE)) return -EPERM; @@ -170,6 +167,11 @@ 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;