[PATCH v9 49/69] fork: use VMA iterator

From: Liam Howlett
Date: Tue May 03 2022 - 21:17:39 EST


From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>

The VMA iterator is faster than the linked list and removing the linked
list will shrink the vm_area_struct.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
kernel/fork.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 4af22dd65fc6..9fcbd0b5c0be 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1291,13 +1291,16 @@ int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
/* Forbid mm->exe_file change if old file still mapped. */
old_exe_file = get_mm_exe_file(mm);
if (old_exe_file) {
+ VMA_ITERATOR(vmi, mm, 0);
mmap_read_lock(mm);
- for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
+ for_each_vma(vmi, vma) {
if (!vma->vm_file)
continue;
if (path_equal(&vma->vm_file->f_path,
- &old_exe_file->f_path))
+ &old_exe_file->f_path)) {
ret = -EBUSY;
+ break;
+ }
}
mmap_read_unlock(mm);
fput(old_exe_file);
--
2.35.1