mm/hmm: do not differentiate between empty entry or missing directory
There is no point in differentiating between a range for which there is not even a directory (and thus entries) and empty entry (pte_none() or pmd_none() returns true). Simply drop the distinction ie remove HMM_PFN_EMPTY flag and merge now duplicate hmm_vma_walk_hole() and hmm_vma_walk_clear() functions. Link: http://lkml.kernel.org/r/20180323005527.758-11-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Evgeny Baskakov <ebaskakov@nvidia.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Mark Hairgrove <mhairgrove@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -84,7 +84,6 @@ struct hmm;
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* HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
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* HMM_PFN_WRITE: CPU page table has write permission set
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* HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory
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* HMM_PFN_EMPTY: corresponding CPU page table entry is pte_none()
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* HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the
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* result of vm_insert_pfn() or vm_insert_page(). Therefore, it should not
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* be mirrored by a device, because the entry will never have HMM_PFN_VALID
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@ -94,10 +93,9 @@ struct hmm;
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#define HMM_PFN_VALID (1 << 0)
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#define HMM_PFN_WRITE (1 << 1)
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#define HMM_PFN_ERROR (1 << 2)
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#define HMM_PFN_EMPTY (1 << 3)
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#define HMM_PFN_SPECIAL (1 << 4)
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#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 5)
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#define HMM_PFN_SHIFT 6
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#define HMM_PFN_SPECIAL (1 << 3)
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#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 4)
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#define HMM_PFN_SHIFT 5
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/*
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* hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn
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45
mm/hmm.c
45
mm/hmm.c
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@ -348,6 +348,16 @@ static void hmm_pfns_clear(uint64_t *pfns,
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*pfns = 0;
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}
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/*
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* hmm_vma_walk_hole() - handle a range lacking valid pmd or pte(s)
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* @start: range virtual start address (inclusive)
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* @end: range virtual end address (exclusive)
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* @walk: mm_walk structure
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* Returns: 0 on success, -EAGAIN after page fault, or page fault error
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*
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* This function will be called whenever pmd_none() or pte_none() returns true,
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* or whenever there is no page directory covering the virtual address range.
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*/
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static int hmm_vma_walk_hole(unsigned long addr,
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unsigned long end,
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struct mm_walk *walk)
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@ -357,31 +367,6 @@ static int hmm_vma_walk_hole(unsigned long addr,
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uint64_t *pfns = range->pfns;
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unsigned long i;
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hmm_vma_walk->last = addr;
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i = (addr - range->start) >> PAGE_SHIFT;
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for (; addr < end; addr += PAGE_SIZE, i++) {
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pfns[i] = HMM_PFN_EMPTY;
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if (hmm_vma_walk->fault) {
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int ret;
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ret = hmm_vma_do_fault(walk, addr, &pfns[i]);
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if (ret != -EAGAIN)
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return ret;
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}
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}
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return hmm_vma_walk->fault ? -EAGAIN : 0;
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}
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static int hmm_vma_walk_clear(unsigned long addr,
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unsigned long end,
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struct mm_walk *walk)
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{
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struct hmm_vma_walk *hmm_vma_walk = walk->private;
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struct hmm_range *range = hmm_vma_walk->range;
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uint64_t *pfns = range->pfns;
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unsigned long i;
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hmm_vma_walk->last = addr;
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i = (addr - range->start) >> PAGE_SHIFT;
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for (; addr < end; addr += PAGE_SIZE, i++) {
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@ -440,10 +425,10 @@ again:
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if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
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goto again;
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if (pmd_protnone(pmd))
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return hmm_vma_walk_clear(start, end, walk);
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return hmm_vma_walk_hole(start, end, walk);
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if (write_fault && !pmd_write(pmd))
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return hmm_vma_walk_clear(start, end, walk);
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return hmm_vma_walk_hole(start, end, walk);
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pfn = pmd_pfn(pmd) + pte_index(addr);
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flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0;
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@ -462,7 +447,7 @@ again:
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pfns[i] = 0;
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if (pte_none(pte)) {
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pfns[i] = HMM_PFN_EMPTY;
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pfns[i] = 0;
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if (hmm_vma_walk->fault)
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goto fault;
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continue;
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@ -513,8 +498,8 @@ again:
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fault:
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pte_unmap(ptep);
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/* Fault all pages in range */
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return hmm_vma_walk_clear(start, end, walk);
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/* Fault any virtual address we were asked to fault */
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return hmm_vma_walk_hole(start, end, walk);
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}
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pte_unmap(ptep - 1);
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