Re: [PATCH 2/3] mm/zswap: Implement proactive writeback

[Hao Jia]

On 2026/5/12 03:54, Nhat Pham wrote:
> On Mon, May 11, 2026 at 3:52 AM Hao Jia <jiahao.kernel@xxxxxxxxx> wrote:
> > diff --git a/mm/zswap.c b/mm/zswap.c
> > index 19538d6f169a..1173ac6836fa 100644
> > --- a/mm/zswap.c
> > +++ b/mm/zswap.c
> > @@ -36,6 +36,7 @@
> >   #include <linux/workqueue.h>
> >   #include <linux/list_lru.h>
> >   #include <linux/zsmalloc.h>
> > +#include <linux/timekeeping.h>
> >
> >   #include "swap.h"
> >   #include "internal.h"
> > @@ -160,6 +161,12 @@ struct zswap_pool {
> >          char tfm_name[CRYPTO_MAX_ALG_NAME];
> >   };
> >
> > +struct zswap_shrink_walk_arg {
> > +       ktime_t cutoff_time;
> > +       bool proactive;
> > +       bool encountered_page_in_swapcache;
> > +};
> > +
> >   /* Global LRU lists shared by all zswap pools. */
> >   static struct list_lru zswap_list_lru;
> >
> > @@ -183,6 +190,7 @@ static struct shrinker *zswap_shrinker;
> >    * handle - zsmalloc allocation handle that stores the compressed page data
> >    * objcg - the obj_cgroup that the compressed memory is charged to
> >    * lru - handle to the pool's lru used to evict pages.
> > + * store_time - Time when the entry was stored, for proactive writeback.
> >    */
> >   struct zswap_entry {
> >          swp_entry_t swpentry;
> > @@ -192,6 +200,7 @@ struct zswap_entry {
> >          unsigned long handle;
> >          struct obj_cgroup *objcg;
> >          struct list_head lru;
> > +       ktime_t store_time;
>
> On the implementation side - will this blow up struct zswap_entry
> memory footprint? If so, can you guard this behind a CONFIG option, if
> we are to go this route?

Thanks for the review. I'll address this in v2.

Thanks,
Hao