Re: [PATCH v5 27/45] vmw_balloon: dynamically allocate the vmw-balloon shrinker

[Qi Zheng]

Hi Nadav,

On 2023/8/24 23:28, Nadav Amit wrote:
> > On Aug 23, 2023, at 8:42 PM, Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
> >
> > In preparation for implementing lockless slab shrink, use new APIs to
> > dynamically allocate the vmw-balloon shrinker, so that it can be freed
> > asynchronously via RCU. Then it doesn't need to wait for RCU read-side
> > critical section when releasing the struct vmballoon.
> >
> > And we can simply exit vmballoon_init() when registering the shrinker
> > fails. So the shrinker_registered indication is redundant, just remove it.
>
> ...
>
> Ugh. We should have already moved to OOM notifier instead...
>
> > static void vmballoon_unregister_shrinker(struct vmballoon *b)
> > {
> > -	if (b->shrinker_registered)
> > -		unregister_shrinker(&b->shrinker);
> > -	b->shrinker_registered = false;
> > +	shrinker_free(b->shrinker);
> > }
>
> If the patch goes through another iteration, please add:
>
> 	b->shrinker = NULL;
>
> Not that this is a real issue, but I prefer it so in order to more easily
> identify UAF if the function is called elsewhere.

OK, will add it.

> Otherwise, LGTM. Thanks.

Thanks for your review!

Qi

>