lkml.org 
[lkml]   [2021]   [Oct]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 12/66] mmap: Change zeroing of maple tree in __vma_adjust
Date
Only write to the maple tree if we are not inserting or the insert isn't
going to overwrite the area to clear. This avoids spanning writes and
node coealescing when unnecessary.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
mm/mmap.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index c51d739d7411..9f047204fa93 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -626,6 +626,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
bool vma_changed = false;
long adjust_next = 0;
int remove_next = 0;
+ unsigned long old_start;

if (next && !insert) {
struct vm_area_struct *exporter = NULL, *importer = NULL;
@@ -751,25 +752,29 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
vma_interval_tree_remove(next, root);
}

+ old_start = vma->vm_start;
if (start != vma->vm_start) {
- if (vma->vm_start < start)
- vma_mt_szero(mm, vma->vm_start, start);
- else
- vma_changed = true;
+ vma_changed = true;
vma->vm_start = start;
}
if (end != vma->vm_end) {
- if (vma->vm_end > end)
- vma_mt_szero(mm, end, vma->vm_end);
- else
+ if (vma->vm_end > end) {
+ if (!insert || (insert && (insert->vm_start != end)))
+ vma_mt_szero(mm, end, vma->vm_end);
+ } else
vma_changed = true;
vma->vm_end = end;
if (!next)
mm->highest_vm_end = vm_end_gap(vma);
}

- if (vma_changed)
+ if (vma_changed) {
vma_mt_store(mm, vma);
+ if (old_start < start) {
+ if (insert && (insert->vm_start != old_start))
+ vma_mt_szero(mm, old_start, start);
+ }
+ }

vma->vm_pgoff = pgoff;
if (adjust_next) {
--
2.30.2
\
 
 \ /
  Last update: 2021-10-05 03:33    [W:0.547 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site