mm/hmm: do not unconditionally set pfns when returning EBUSY (846babe8) · Commits · 戴 / test

In hmm_vma_handle_pte() and hmm_vma_walk_hugetlb_entry() if fault happens then -EBUSY will be returned and the pfns input flags will have been destroyed. For hmm_vma_handle_pte() set HMM_PFN_NONE only on the success returns that don't otherwise store to pfns. For hmm_vma_walk_hugetlb_entry() all exit paths already set pfns, so remove the redundant store. Fixes: ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Link: https://lore.kernel.org/r/20200327200021.29372-8-jgg@ziepe.ca Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Jason Gunthorpe <jgg@mellanox.com>

mm/hmm.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -250,11 +250,11 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
		pte_t pte = *ptep;
		uint64_t orig_pfn = *pfn;

		*pfn = range->values[HMM_PFN_NONE];
		if (pte_none(pte)) {
		required_fault = hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0);
		if (required_fault)
		goto fault;
		*pfn = range->values[HMM_PFN_NONE];
		return 0;
		}

		@@ -275,8 +275,10 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
		}

		required_fault = hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0);
		if (!required_fault)
		if (!required_fault) {
		*pfn = range->values[HMM_PFN_NONE];
		return 0;
		}

		if (!non_swap_entry(entry))
		goto fault;
		@@ -494,7 +496,6 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,

		i = (start - range->start) >> PAGE_SHIFT;
		orig_pfn = range->pfns[i];
		range->pfns[i] = range->values[HMM_PFN_NONE];
		cpu_flags = pte_to_hmm_pfn_flags(range, entry);
		required_fault = hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags);
		if (required_fault) {

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