Re: [PATCH v4 06/22] mm/zsmalloc: convert create_page_chain() and its users to use zpdesc

[Alex Shi]

On 8/3/24 3:09 AM, Vishal Moola wrote:
> On Mon, Jul 29, 2024 at 07:25:18PM +0800, alexs@xxxxxxxxxx wrote:
>> From: Alex Shi <alexs@xxxxxxxxxx>
>>
>> Introduce a few helper functions for conversion to convert create_page_chain()
>> to use zpdesc, then use zpdesc in replace_sub_page() too.
> 
> As a general note, I've been having trouble keeping track of your helper
> functions throughout your patchset. Things get confusing when helper
> functions are "add-ons" to patches and are then replaced/rewritten
> in various subsequent patches - might just be me though.

Right, maybe too much helper doesn't give necessary help.

> 
>> Originally-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
>> Signed-off-by: Alex Shi <alexs@xxxxxxxxxx>
>> ---
>>  mm/zpdesc.h   |   6 +++
>>  mm/zsmalloc.c | 115 +++++++++++++++++++++++++++++++++-----------------
>>  2 files changed, 82 insertions(+), 39 deletions(-)
>>
>> diff --git a/mm/zpdesc.h b/mm/zpdesc.h
>> index 79ec40b03956..2293453f5d57 100644
>> --- a/mm/zpdesc.h
>> +++ b/mm/zpdesc.h
>> @@ -102,4 +102,10 @@ static inline struct zpdesc *pfn_zpdesc(unsigned long pfn)
>>  {
>>  	return page_zpdesc(pfn_to_page(pfn));
>>  }
>> +
>> +static inline void __zpdesc_set_movable(struct zpdesc *zpdesc,
>> +					const struct movable_operations *mops)
>> +{
>> +	__SetPageMovable(zpdesc_page(zpdesc), mops);
>> +}
>>  #endif
>> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
>> index bbc165cb587d..a8f390beeab8 100644
>> --- a/mm/zsmalloc.c
>> +++ b/mm/zsmalloc.c
>> @@ -248,6 +248,41 @@ static inline void *zpdesc_kmap_atomic(struct zpdesc *zpdesc)
>>  	return kmap_atomic(zpdesc_page(zpdesc));
>>  }
>>  
>> +static inline void zpdesc_set_zspage(struct zpdesc *zpdesc,
>> +				     struct zspage *zspage)
>> +{
>> +	zpdesc->zspage = zspage;
>> +}
>> +
>> +static inline void zpdesc_set_first(struct zpdesc *zpdesc)
>> +{
>> +	SetPagePrivate(zpdesc_page(zpdesc));
>> +}
>> +
> 
> I'm not a fan of the names above. IMO, naming should follow some
> semblance of consistency regarding their purpose (or have comments
> that describe their purpose instead).
> 
> At a glance zpdesc_set_zspage() and zpdesc_set_first() sound like they
> are doing similar things, but I don't think they serve similar purposes?

zpdesc_set_zspage() only used in one place, a helper maynot needed. Let me remove it.
Same thing for the alloc_zpdesc() and free_zpdesc(), they could be merge into using place.

Thanks
Alex
> 
>> +static inline void zpdesc_inc_zone_page_state(struct zpdesc *zpdesc)
>> +{
>> +	inc_zone_page_state(zpdesc_page(zpdesc), NR_ZSPAGES);
>> +}
>> +
>> +static inline void zpdesc_dec_zone_page_state(struct zpdesc *zpdesc)
>> +{
>> +	dec_zone_page_state(zpdesc_page(zpdesc), NR_ZSPAGES);
>> +}
>> +
>> +static inline struct zpdesc *alloc_zpdesc(gfp_t gfp)
>> +{
>> +	struct page *page = alloc_page(gfp);
>> +
>> +	return page_zpdesc(page);
>> +}
>> +
>> +static inline void free_zpdesc(struct zpdesc *zpdesc)
>> +{
>> +	struct page *page = zpdesc_page(zpdesc);
>> +
>> +	__free_page(page);
>> +}
>> +
>