The patch titled
Subject: mm/hmm: do not differentiate between empty entry or missing directory
has been added to the -mm tree. Its filename is
mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory.patch
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------------------------------------------------------
From: Jérôme Glisse <jglisse@xxxxxxxxxx>
Subject: 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 an 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/20180316191414.3223-10-jglisse@xxxxxxxxxx
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/hmm.h | 8 ++-----
mm/hmm.c | 45 ++++++++++++++----------------------------
2 files changed, 18 insertions(+), 35 deletions(-)
diff -puN include/linux/hmm.h~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory include/linux/hmm.h
--- a/include/linux/hmm.h~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory
+++ a/include/linux/hmm.h
@@ -84,7 +84,6 @@ struct hmm;
* HMM_PFN_VALID: pfn is valid
* 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
diff -puN mm/hmm.c~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory mm/hmm.c
--- a/mm/hmm.c~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory
+++ a/mm/hmm.c
@@ -305,6 +305,16 @@ static void hmm_pfns_clear(uint64_t *pfn
*pfns = 0;
}
+/*
+ * hmm_vma_walk_hole() - handle a range back by no pmd or no pte
+ * @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 is an helper call whenever pmd_none() or pte_none() returns true
+ * or when there is no directory covering the range.
+ */
static int hmm_vma_walk_hole(unsigned long addr,
unsigned long end,
struct mm_walk *walk)
@@ -317,31 +327,6 @@ static int hmm_vma_walk_hole(unsigned lo
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++) {
pfns[i] = 0;
if (hmm_vma_walk->fault) {
int ret;
@@ -397,10 +382,10 @@ 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;
@@ -419,7 +404,7 @@ again:
pfns[i] = 0;
if (pte_none(pte)) {
- pfns[i] = HMM_PFN_EMPTY;
+ pfns[i] = 0;
if (hmm_vma_walk->fault)
goto fault;
continue;
@@ -470,8 +455,8 @@ again:
fault:
pte_unmap(ptep);
- /* Fault all pages in range */
- return hmm_vma_walk_clear(start, end, walk);
+ /* Fault all pages in range if ask for */
+ return hmm_vma_walk_hole(start, end, walk);
}
pte_unmap(ptep - 1);
_
Patches currently in -mm which might be from jglisse@xxxxxxxxxx are
mm-hmm-fix-header-file-if-else-endif-maze.patch
mm-hmm-hmm_pfns_bad-was-accessing-wrong-struct.patch
mm-hmm-use-struct-for-hmm_vma_fault-hmm_vma_get_pfns-parameters.patch
mm-hmm-remove-hmm_pfn_read-flag-and-ignore-peculiar-architecture.patch
mm-hmm-use-uint64_t-for-hmm-pfn-instead-of-defining-hmm_pfn_t-to-ulong.patch
mm-hmm-cleanup-special-vma-handling-vm_special.patch
mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory.patch
mm-hmm-rename-hmm_pfn_device_unaddressable-to-hmm_pfn_device_private.patch
mm-hmm-move-hmm_pfns_clear-closer-to-where-it-is-use.patch
mm-hmm-factor-out-pte-and-pmd-handling-to-simplify-hmm_vma_walk_pmd.patch
mm-hmm-change-hmm_vma_fault-to-allow-write-fault-on-page-basis.patch
mm-hmm-use-device-driver-encoding-for-hmm-pfn.patch
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