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From: akpm@linux-foundation.org
To: mm-commits@vger.kernel.org, yang.shi@linux.alibaba.com,
	thellstrom@vmware.com, kirill@shutemov.name,
	dan.j.williams@intel.com, aneesh.kumar@linux.ibm.com,
	richardw.yang@linux.intel.com
Subject: + mm-mremap-calculate-extent-in-one-place.patch added to -mm tree
Date: Sat, 18 Jan 2020 16:07:13 -0800	[thread overview]
Message-ID: <20200119000713.SM_le%akpm@linux-foundation.org> (raw)


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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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Wei Yang <richardw.yang@linux.intel.com>
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@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@linux.intel.com 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

             reply	other threads:[~2020-01-19  0:07 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-19  0:07 akpm [this message]
2020-07-01  2:31 akpm
2020-07-03 22:14 incoming Andrew Morton
2020-07-08 23:16 ` + mm-mremap-calculate-extent-in-one-place.patch added to -mm tree Andrew Morton

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