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

[Hao Jia <jiahao.kernel@gmail.com>]

On 2026/5/12 03:54, Nhat Pham wrote:
> On Mon, May 11, 2026 at 3:52 AM Hao Jia <jiahao.kernel@gmail.com> 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