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

On 22.11.24 07:19, Andrew Morton wrote:

On Wed, 20 Nov 2024 15:27:46 -0500 "Liam R. Howlett" Liam.Howlett@oracle.com 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; }

_

?

Why not, at least for documentation purposes. Because I don't think this is any fast-path we really care about, so expect the runtime effects to be mostly negligible. Thanks!