The patch titled
Subject: mm/mremap: calculate extent in one place
has been added to the -mm tree. Its filename is
mm-mremap-calculate-extent-in-one-place.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mremap-calculate-extent-in-one-place.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mremap-calculate-extent-in-one-place.patch
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------------------------------------------------------
From: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Subject: mm/mremap: calculate extent in one place
Page tables is moved on the base of PMD. This requires both source and
destination range should meet the requirement.
Current code works well since move_huge_pmd() and move_normal_pmd() would
check old_addr and new_addr again. And then return to move_ptes() if the
either of them is not aligned.
In stead of calculating the extent separately, it is better to calculate
in one place, so we know it is not necessary to try move pmd. By doing
so, the logic seems a little clear.
Link: http://lkml.kernel.org/r/20200117232254.2792-5-richardw.yang@xxxxxxxxxxxxxxx
Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mremap.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- a/mm/mremap.c~mm-mremap-calculate-extent-in-one-place
+++ a/mm/mremap.c
@@ -240,7 +240,7 @@ unsigned long move_page_tables(struct vm
unsigned long new_addr, unsigned long len,
bool need_rmap_locks)
{
- unsigned long extent, next, old_end;
+ unsigned long extent, old_next, new_next, old_end;
struct mmu_notifier_range range;
pmd_t *old_pmd, *new_pmd;
@@ -253,8 +253,9 @@ unsigned long move_page_tables(struct vm
for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
cond_resched();
- next = pmd_addr_end(old_addr, old_end);
- extent = next - old_addr;
+ old_next = pmd_addr_end(old_addr, old_end);
+ new_next = pmd_addr_end(new_addr, new_addr + len);
+ extent = min((old_next - old_addr), (new_next - new_addr));
old_pmd = get_old_pmd(vma->vm_mm, old_addr);
if (!old_pmd)
continue;
@@ -298,9 +299,6 @@ unsigned long move_page_tables(struct vm
if (pte_alloc(new_vma->vm_mm, new_pmd))
break;
- next = pmd_addr_end(new_addr, new_addr + len);
- if (extent > next - new_addr)
- extent = next - new_addr;
move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma,
new_pmd, new_addr, need_rmap_locks);
}
_
Patches currently in -mm which might be from richardw.yang@xxxxxxxxxxxxxxx are
mm-thp-remove-the-defer-list-related-code-since-this-will-not-happen.patch
mm-gupc-use-is_vm_hugetlb_page-to-check-whether-to-follow-huge.patch
mm-mremap-format-the-check-in-move_normal_pmd-same-as-move_huge_pmd.patch
mm-mremap-it-is-sure-to-have-enough-space-when-extent-meets-requirement.patch
mm-mremap-use-pmd_addr_end-to-calculate-next-in-move_page_tables.patch
mm-mremap-calculate-extent-in-one-place.patch
mm-mremap-start-addresses-are-properly-aligned.patch
mm-huge_memoryc-use-head-to-check-huge-zero-page.patch
mm-huge_memoryc-use-head-to-emphasize-the-purpose-of-page.patch
mm-huge_memoryc-reduce-critical-section-protected-by-split_queue_lock.patch
mm-remove-dead-code-totalram_pages_set.patch
