Re: [PATCH v1] mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM

[Andrew Morton]

On Wed, 20 Nov 2024 15:27:46 -0500 "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> wrote:

> I hate the extra check because syzbot can cause this as this should
> basically never happen in real life, but it seems we have to add it.

So..

--- a/mm/mempolicy.c~mm-mempolicy-fix-migrate_to_node-assuming-there-is-at-least-one-vma-in-a-mm-fix
+++ a/mm/mempolicy.c
@@ -1080,7 +1080,7 @@ static long migrate_to_node(struct mm_st
 
 	mmap_read_lock(mm);
 	vma = find_vma(mm, 0);
-	if (!vma) {
+	if (unlikely(!vma)) {
 		mmap_read_unlock(mm);
 		return 0;
 	}
_

?