From 160c820023bbfe7c478ed3041cc50604d664f047 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Tue, 6 Sep 2022 19:48:58 +0000
Subject: [PATCH] acct: use VMA iterator instead of linked list

The VMA iterator is faster than the linked list.

Link: https://lkml.kernel.org/r/20220906194824.2110408-47-Liam.Howlett@oracle.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 kernel/acct.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/acct.c b/kernel/acct.c
index 1370635..62200d7 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -555,15 +555,14 @@ void acct_collect(long exitcode, int group_dead)
 	unsigned long vsize = 0;
 
 	if (group_dead && current->mm) {
+		struct mm_struct *mm = current->mm;
+		VMA_ITERATOR(vmi, mm, 0);
 		struct vm_area_struct *vma;
 
-		mmap_read_lock(current->mm);
-		vma = current->mm->mmap;
-		while (vma) {
+		mmap_read_lock(mm);
+		for_each_vma(vmi, vma)
 			vsize += vma->vm_end - vma->vm_start;
-			vma = vma->vm_next;
-		}
-		mmap_read_unlock(current->mm);
+		mmap_read_unlock(mm);
 	}
 
 	spin_lock_irq(&current->sighand->siglock);
-- 
2.7.4