mm/hmm: return error for non-vma snapshots (bd5d3587) · Commits · 戴 / test

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>

mm/hmm.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -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;

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