Re: [PATCH] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb

[Andrew Morton]

On Wed, 17 Jan 2024 14:37:29 -0800 Lokesh Gidra <lokeshgidra@xxxxxxxxxx> wrote:

> In mfill_atomic_hugetlb(), mmap_changing isn't being checked
> again if we drop mmap_lock and reacquire it. When the lock is not held,
> mmap_changing could have been incremented. This is also inconsistent
> with the behavior in mfill_atomic().

Thanks. Could you and reviewers please consider

- what might be the userspace-visible runtime effects?

- Should the fix be backported into earlier kernels?

- A suitable Fixes: target?