The patch titled
Subject: x86, mm: unify exit paths in gup_pte_range()
has been added to the -mm tree. Its filename is
x86-mm-unify-exit-paths-in-gup_pte_range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-mm-unify-exit-paths-in-gup_pte_range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-mm-unify-exit-paths-in-gup_pte_range.patch
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From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: x86, mm: unify exit paths in gup_pte_range()
All exit paths from gup_pte_range() require pte_unmap() of the original
pte page before returning. Refactor the code to have a single exit point
to do the unmap.
This mirrors the flow of the generic gup_pte_range() in mm/gup.c.
Link: http://lkml.kernel.org/r/148804251828.36605.14910389618497006945.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/gup.c | 41 +++++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 20 deletions(-)
diff -puN arch/x86/mm/gup.c~x86-mm-unify-exit-paths-in-gup_pte_range arch/x86/mm/gup.c
--- a/arch/x86/mm/gup.c~x86-mm-unify-exit-paths-in-gup_pte_range
+++ a/arch/x86/mm/gup.c
@@ -106,36 +106,35 @@ static noinline int gup_pte_range(pmd_t
unsigned long end, int write, struct page **pages, int *nr)
{
struct dev_pagemap *pgmap = NULL;
- int nr_start = *nr;
- pte_t *ptep;
+ int nr_start = *nr, ret = 0;
+ pte_t *ptep, *ptem;
- ptep = pte_offset_map(&pmd, addr);
+ /*
+ * Keep the original mapped PTE value (ptem) around since we
+ * might increment ptep off the end of the page when finishing
+ * our loop iteration.
+ */
+ ptem = ptep = pte_offset_map(&pmd, addr);
do {
pte_t pte = gup_get_pte(ptep);
struct page *page;
/* Similar to the PMD case, NUMA hinting must take slow path */
- if (pte_protnone(pte)) {
- pte_unmap(ptep);
- return 0;
- }
-
- if (!pte_allows_gup(pte_val(pte), write)) {
- pte_unmap(ptep);
- return 0;
- }
+ if (pte_protnone(pte))
+ break;
+
+ if (!pte_allows_gup(pte_val(pte), write))
+ break;
if (pte_devmap(pte)) {
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, pages);
- pte_unmap(ptep);
- return 0;
+ break;
}
- } else if (pte_special(pte)) {
- pte_unmap(ptep);
- return 0;
- }
+ } else if (pte_special(pte))
+ break;
+
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
page = pte_page(pte);
get_page(page);
@@ -145,9 +144,11 @@ static noinline int gup_pte_range(pmd_t
(*nr)++;
} while (ptep++, addr += PAGE_SIZE, addr != end);
- pte_unmap(ptep - 1);
+ if (addr == end)
+ ret = 1;
+ pte_unmap(ptem);
- return 1;
+ return ret;
}
static inline void get_head_page_multiple(struct page *page, int nr)
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
x86-mm-fix-gup_pte_range-vs-dax-mappings.patch
x86-mm-unify-exit-paths-in-gup_pte_range.patch
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