Re: [PATCH] mm: swap: check for xa_zero_entry() on vma in swapoff path

[David Hildenbrand]

On 11.08.25 17:48, Lorenzo Stoakes wrote:
> On Mon, Aug 11, 2025 at 05:39:32PM +0200, David Hildenbrand wrote:
> > > I could make a function that frees all new vmas and destroys the tree
> > > specifically for this failure state?
> >
> > I think the problem is that some page tables were already copied, so we
> > would have to zap them as well.
>
> This shouldn't be too much more egregious?
>
> The issues arise when it might be an OOM issue, but if it's a fatal signal we
> can take the time to clean up.
>
> > Maybe just factoring stuff from the exit_mmap() function could be one way to
> > do it.
>
> Is exit_mmap() a problem here? Or maybe I don't understand what you're getting
> at.

We are dropping the write lock in between, allowing for these races.

--
Cheers,

David / dhildenb