Commit 5504ed29 authored by Jérôme Glisse's avatar Jérôme Glisse Committed by Linus Torvalds
Browse files

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: default avatarJérôme Glisse <jglisse@redhat.com>
Reviewed-by: default avatarJohn 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 855ce7d2

include/linux/hmm.h

+3 −5
Original line number Diff line number Diff line
@@ -84,7 +84,6 @@ struct hmm; 
 * HMM_PFN_VALID: pfn is valid. It has, at least, read permission.

 * HMM_PFN_WRITE: CPU page table has write permission set

 * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory

 * HMM_PFN_EMPTY: corresponding CPU page table entry is pte_none()

 * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the

 *      result of vm_insert_pfn() or vm_insert_page(). Therefore, it should not

 *      be mirrored by a device, because the entry will never have HMM_PFN_VALID
@@ -94,10 +93,9 @@ struct hmm; 
#define HMM_PFN_VALID (1 << 0)

#define HMM_PFN_WRITE (1 << 1)

#define HMM_PFN_ERROR (1 << 2)

#define HMM_PFN_EMPTY (1 << 3)

#define HMM_PFN_SPECIAL (1 << 4)

#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 5)

#define HMM_PFN_SHIFT 6

#define HMM_PFN_SPECIAL (1 << 3)

#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 4)

#define HMM_PFN_SHIFT 5



/*

 * hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn

mm/hmm.c

+15 −30
Original line number Diff line number Diff line
@@ -348,6 +348,16 @@ static void hmm_pfns_clear(uint64_t *pfns, 
		*pfns = 0;

}



/*

 * hmm_vma_walk_hole() - handle a range lacking valid pmd or pte(s)

 * @start: range virtual start address (inclusive)

 * @end: range virtual end address (exclusive)

 * @walk: mm_walk structure

 * Returns: 0 on success, -EAGAIN after page fault, or page fault error

 *

 * This function will be called whenever pmd_none() or pte_none() returns true,

 * or whenever there is no page directory covering the virtual address range.

 */

static int hmm_vma_walk_hole(unsigned long addr,

			     unsigned long end,

			     struct mm_walk *walk)
@@ -357,31 +367,6 @@ static int hmm_vma_walk_hole(unsigned long addr, 
	uint64_t *pfns = range->pfns;

	unsigned long i;



	hmm_vma_walk->last = addr;

	i = (addr - range->start) >> PAGE_SHIFT;

	for (; addr < end; addr += PAGE_SIZE, i++) {

		pfns[i] = HMM_PFN_EMPTY;

		if (hmm_vma_walk->fault) {

			int ret;



			ret = hmm_vma_do_fault(walk, addr, &pfns[i]);

			if (ret != -EAGAIN)

				return ret;

		}

	}



	return hmm_vma_walk->fault ? -EAGAIN : 0;

}



static int hmm_vma_walk_clear(unsigned long addr,

			      unsigned long end,

			      struct mm_walk *walk)

{

	struct hmm_vma_walk *hmm_vma_walk = walk->private;

	struct hmm_range *range = hmm_vma_walk->range;

	uint64_t *pfns = range->pfns;

	unsigned long i;



	hmm_vma_walk->last = addr;

	i = (addr - range->start) >> PAGE_SHIFT;

	for (; addr < end; addr += PAGE_SIZE, i++) {
@@ -440,10 +425,10 @@ again: 
		if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))

			goto again;

		if (pmd_protnone(pmd))

			return hmm_vma_walk_clear(start, end, walk);

			return hmm_vma_walk_hole(start, end, walk);



		if (write_fault && !pmd_write(pmd))

			return hmm_vma_walk_clear(start, end, walk);

			return hmm_vma_walk_hole(start, end, walk);



		pfn = pmd_pfn(pmd) + pte_index(addr);

		flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0;
@@ -462,7 +447,7 @@ again: 
		pfns[i] = 0;



		if (pte_none(pte)) {

			pfns[i] = HMM_PFN_EMPTY;

			pfns[i] = 0;

			if (hmm_vma_walk->fault)

				goto fault;

			continue;
@@ -513,8 +498,8 @@ again: 


fault:

		pte_unmap(ptep);

		/* Fault all pages in range */

		return hmm_vma_walk_clear(start, end, walk);

		/* Fault any virtual address we were asked to fault */

		return hmm_vma_walk_hole(start, end, walk);

	}

	pte_unmap(ptep - 1);

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