linux-kernel - Re: [PATCH v1 06/29] mm/zsmalloc: make PageZsmalloc() sticky until the page is freed

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Message-ID: <7a194ee3-f5c3-416e-8de2-d2beb32479a8@redhat.com>
Date: Tue, 1 Jul 2025 10:27:24 +0200
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
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Subject: Re: [PATCH v1 06/29] mm/zsmalloc: make PageZsmalloc() sticky until
 the page is freed

On 30.06.25 18:03, Lorenzo Stoakes wrote:
> On Mon, Jun 30, 2025 at 02:59:47PM +0200, David Hildenbrand wrote:
>> Let the page freeing code handle clearing the page type.
>>
>> Acked-by: Zi Yan <ziy@...dia.com>
>> Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
>> Acked-by: Harry Yoo <harry.yoo@...cle.com>
>> Signed-off-by: David Hildenbrand <david@...hat.com>
> 
> On basis of sanity of UINT_MAX thing:
> 
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> 
>> ---
>>   mm/zpdesc.h   | 5 -----
>>   mm/zsmalloc.c | 3 +--
>>   2 files changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/mm/zpdesc.h b/mm/zpdesc.h
>> index 5cb7e3de43952..5763f36039736 100644
>> --- a/mm/zpdesc.h
>> +++ b/mm/zpdesc.h
>> @@ -163,11 +163,6 @@ static inline void __zpdesc_set_zsmalloc(struct zpdesc *zpdesc)
>>   	__SetPageZsmalloc(zpdesc_page(zpdesc));
>>   }
>>
>> -static inline void __zpdesc_clear_zsmalloc(struct zpdesc *zpdesc)
>> -{
>> -	__ClearPageZsmalloc(zpdesc_page(zpdesc));
>> -}
>> -
>>   static inline struct zone *zpdesc_zone(struct zpdesc *zpdesc)
>>   {
>>   	return page_zone(zpdesc_page(zpdesc));
>> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
>> index 7f1431f2be98f..f98747aed4330 100644
>> --- a/mm/zsmalloc.c
>> +++ b/mm/zsmalloc.c
>> @@ -880,7 +880,7 @@ static void reset_zpdesc(struct zpdesc *zpdesc)
>>   	ClearPagePrivate(page);
>>   	zpdesc->zspage = NULL;
>>   	zpdesc->next = NULL;
>> -	__ClearPageZsmalloc(page);
>> +	/* PageZsmalloc is sticky until the page is freed to the buddy. */
>>   }
>>
>>   static int trylock_zspage(struct zspage *zspage)
>> @@ -1055,7 +1055,6 @@ static struct zspage *alloc_zspage(struct zs_pool *pool,
>>   		if (!zpdesc) {
>>   			while (--i >= 0) {
>>   				zpdesc_dec_zone_page_state(zpdescs[i]);
> 
> Maybe for consistency put a
> 
> /* PageZsmalloc is sticky until the page is freed to the buddy. */
> 

I'll add that inside free_zpdesc(), before the __free_page().

Thanks!

-- 
Cheers,

David / dhildenb