mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling (40550627) · Commits · 戴 / test

Currently if a special PTE is encountered hmm_range_fault() immediately returns EFAULT and sets the HMM_PFN_SPECIAL error output (which nothing uses). EFAULT should only be returned after testing with hmm_pte_need_fault(). Also pte_devmap() and pte_special() are exclusive, and there is no need to check IS_ENABLED, pte_special() is stubbed out to return false on unsupported architectures. Fixes: ("mm/hmm: allow to mirror vma of a file on a DAX backed filesystem") Reviewed-by:

Ralph Campbell <rcampbell@nvidia.com> Reviewed-by:

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

Jason Gunthorpe <jgg@mellanox.com>

mm/hmm.c

+12 −7

Original line number	Diff line number	Diff line
		@@ -339,16 +339,21 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
		pte_unmap(ptep);
		return -EBUSY;
		}
		} else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) {
		if (!is_zero_pfn(pte_pfn(pte))) {
		pte_unmap(ptep);
		*pfn = range->values[HMM_PFN_SPECIAL];
		return -EFAULT;
		}

		/*
		* Since each architecture defines a struct page for the zero
		* page, just fall through and treat it like a normal page.
		* Since each architecture defines a struct page for the zero page, just
		* fall through and treat it like a normal page.
		*/
		if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) {
		hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0, &fault,
		&write_fault);
		if (fault \|\| write_fault) {
		pte_unmap(ptep);
		return -EFAULT;
		}
		*pfn = range->values[HMM_PFN_SPECIAL];
		return 0;
		}

		*pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) \| cpu_flags;

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