From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Mon, 21 Sep 2020 16:22:15 +0000 (-0400)
Subject: mm: Change mmap do_brk_flags() to populate the existing VMA
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d854db8bd54b39b72ae421edd5287667b68c6cb6;p=users%2Fjedix%2Flinux-maple.git

mm: Change mmap do_brk_flags() to populate the existing VMA

do_brk_flags has already located the modified VMA, so just populate the
region.  Add mm_populate_vma() to mm/gup.c and call the new function
which ignores errors.

Benckmarks in KVM before:
$ ./mmtests/work/sources/wis-0-installed/brk1_threads
testcase:brk increase/decrease of one page
warmup
min:886150 max:886150 total:886150
min:901488 max:901488 total:901488
min:897594 max:897594 total:897594
min:897422 max:897422 total:897422
min:900700 max:900700 total:900700
min:900714 max:900714 total:900714
measurement
min:903016 max:903016 total:903016
min:901224 max:901224 total:901224
min:902626 max:902626 total:902626
min:900518 max:900518 total:900518

Benchmark in KVM after change:
/mmtests/work/sources/wis-0-installed/brk1_threads
testcase:brk increase/decrease of one page
warmup
min:895650 max:895650 total:895650
min:904936 max:904936 total:904936
min:904776 max:904776 total:904776
min:905358 max:905358 total:905358
min:908792 max:908792 total:908792
min:907648 max:907648 total:907648
measurement
min:904368 max:904368 total:904368
min:903936 max:903936 total:903936
min:904720 max:904720 total:904720
min:906626 max:906626 total:906626

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/mm/gup.c b/mm/gup.c
index 102877ed77a4..522f8fd491ea 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1431,6 +1431,26 @@ long populate_vma_page_range(struct vm_area_struct *vma,
 				NULL, NULL, locked);
 }
 
+/*
+ * mm_populate_vma() - Populate a single range in a single vma.
+ * @vma: The vma to populate.
+ * @start: The start address to populate
+ * @end: The end address to stop populating
+ *
+ * Note: Ignores errors.
+ */
+void mm_populate_vma(struct vm_area_struct *vma, unsigned long start,
+		unsigned long end)
+{
+	struct mm_struct *mm = current->mm;
+	int locked = 1;
+
+	mmap_read_lock(mm);
+	populate_vma_page_range(vma, start, end, &locked);
+	if (locked)
+		mmap_read_unlock(mm);
+}
+
 /*
  * __mm_populate - populate and/or mlock pages within a range of address space.
  *
diff --git a/mm/mmap.c b/mm/mmap.c
index cffa49eaf2b8..3e8426baba8b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -277,7 +277,7 @@ success:
 		mmap_write_unlock(mm);
 	userfaultfd_unmap_complete(mm, &uf);
 	if (populate)
-		mm_populate(oldbrk, newbrk - oldbrk);
+		mm_populate_vma(vma_brk, oldbrk, newbrk);
 	return brk;
 
 out: