Re: [PATCH v2 1/4] mm: memcontrol: correct the type of stats_updates to unsigned long

Lorenzo Stoakes (Oracle)
2026-03-26T08:06:09Z

On Thu, Mar 26, 2026 at 10:32:43AM +0800, Qi Zheng wrote:
>
>
> On 3/25/26 11:28 PM, Lorenzo Stoakes (Oracle) wrote:
> > On Wed, Mar 25, 2026 at 10:13:22PM +0800, Qi Zheng wrote:
> > > From: Qi Zheng <zhengqi.arch@bytedance.com>
> > >
> > > The memcg_rstat_updated() tracks updates for vmstats_percpu->state
> > > and lruvec_stats_percpu->state. Since these state values are of type long,
> > > change the val parameter passed to memcg_rstat_updated() to long as well.
> > >
> > > Correspondingly, change the type of stats_updates in struct
> > > memcg_vmstats_percpu and struct memcg_vmstats from unsigned int and
> > > atomic_t to unsigned long and atomic_long_t respectively to prevent
> > > potential overflow when handling large state updates during the
> > > reparenting of LRU folios.
> >
> > Do we need a Fixes, possibly cc: stable for that? Apologies if already
> > asked + answered.
>
> Before LRU folio reparenting was introduced, we wouldn’t pass in such a
> large value, so this wasn’t a problem. Since LRU folio reparenting is
> still in mm-unstable, so I didn't add a Fixes tag in [4/4].

Ah, well these patches should be _before_ the LRU folio reparenting then?

Andrew - can we ensure correct ordering here?

>
> >
> > >
> > > Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> >
> > Anyway logic seems fine to me, so:
> >
> > Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
>
> Thanks!
>
>

Thanks, Lorenzo