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mm/hmm: return error for non-vma snapshots

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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().

Link: https://lore.kernel.org/r/20200327200021.29372-10-jgg@ziepe.ca
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2020-03-27 17:00:21 -03:00
parent 53bfe17ff8
commit bd5d3587b2
1 changed files with 5 additions and 3 deletions
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8
mm/hmm.c
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@ -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;