Subject: Re: linux-next: manual merge of the akpm-current tree with the folio tree

From: Stephen Rothwell <[email-masked]>
Date: Mon, 6 Sep 2021 14:48:07 +1000

Hi all,

On Wed, 21 Jul 2021 16:31:18 +1000 Stephen Rothwell <[email-masked]> wrote:
> 
> Today's linux-next merge of the akpm-current tree got conflicts in:
> 
>   include/linux/memcontrol.h
>   mm/memcontrol.c
> 
> between commits:
> 
>   05bb7bbab428 ("mm/memcg: Convert mem_cgroup_charge() to take a folio")
>   8b2afb6a1c34 ("mm/memcg: Convert mem_cgroup_uncharge() to take a folio")
> 
> from the folio tree and commit:
> 
>   1f4c6a1cf274 ("mm, memcg: inline mem_cgroup_{charge/uncharge} to improve disabled memcg config")
> 
> from the akpm-current tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> diff --cc include/linux/memcontrol.h
> index af9c44bb1e42,406058a0c480..000000000000
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@@ -704,15 -691,37 +702,36 @@@ static inline bool mem_cgroup_below_min
>   		page_counter_read(&memcg->memory);
>   }
>   
> - int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp);
>  -int __mem_cgroup_charge(struct page *page, struct mm_struct *mm,
>  -			gfp_t gfp_mask);
>  -static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
>  -				    gfp_t gfp_mask)
> ++int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp);
> ++static inline int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm,
> ++				    gfp_t gfp)
> + {
> + 	if (mem_cgroup_disabled())
> + 		return 0;
>  -	return __mem_cgroup_charge(page, mm, gfp_mask);
> ++	return __mem_cgroup_charge(folio, mm, gfp);
> + }
> + 
>   int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
>   				  gfp_t gfp, swp_entry_t entry);
>   void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);
>   
> - void mem_cgroup_uncharge(struct folio *folio);
> - void mem_cgroup_uncharge_list(struct list_head *page_list);
>  -void __mem_cgroup_uncharge(struct page *page);
>  -static inline void mem_cgroup_uncharge(struct page *page)
> ++void __mem_cgroup_uncharge(struct folio *folio);
> ++static inline void mem_cgroup_uncharge(struct folio *folio)
> + {
> + 	if (mem_cgroup_disabled())
> + 		return;
>  -	__mem_cgroup_uncharge(page);
> ++	__mem_cgroup_uncharge(folio);
> + }
> + 
> + void __mem_cgroup_uncharge_list(struct list_head *page_list);
> + static inline void mem_cgroup_uncharge_list(struct list_head *page_list)
> + {
> + 	if (mem_cgroup_disabled())
> + 		return;
> + 	__mem_cgroup_uncharge_list(page_list);
> + }
>   
>  -void mem_cgroup_migrate(struct page *oldpage, struct page *newpage);
>  +void mem_cgroup_migrate(struct folio *old, struct folio *new);
>   
>   /**
>    * mem_cgroup_lruvec - get the lru list vector for a memcg & node
> diff --cc mm/memcontrol.c
> index 1d77c873463c,c010164172dd..000000000000
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@@ -6712,29 -6718,27 +6708,26 @@@ out
>   }
>   
>   /**
> -  * mem_cgroup_charge - Charge a newly allocated folio to a cgroup.
>  - * __mem_cgroup_charge - charge a newly allocated page to a cgroup
>  - * @page: page to charge
>  - * @mm: mm context of the victim
>  - * @gfp_mask: reclaim mode
> ++ * __mem_cgroup_charge - Charge a newly allocated folio to a cgroup.
>  + * @folio: Folio to charge.
>  + * @mm: mm context of the allocating task.
>  + * @gfp: Reclaim mode.
>    *
>  - * Try to charge @page to the memcg that @mm belongs to, reclaiming
>  - * pages according to @gfp_mask if necessary. if @mm is NULL, try to
>  + * Try to charge @folio to the memcg that @mm belongs to, reclaiming
>  + * pages according to @gfp if necessary.  If @mm is NULL, try to
>    * charge to the active memcg.
>    *
>  - * Do not use this for pages allocated for swapin.
>  + * Do not use this for folios allocated for swapin.
>    *
>  - * Returns 0 on success. Otherwise, an error code is returned.
>  + * Return: 0 on success. Otherwise, an error code is returned.
>    */
> - int mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
>  -int __mem_cgroup_charge(struct page *page, struct mm_struct *mm,
>  -			gfp_t gfp_mask)
> ++int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
>   {
>   	struct mem_cgroup *memcg;
>   	int ret;
>   
> - 	if (mem_cgroup_disabled())
> - 		return 0;
> - 
>   	memcg = get_mem_cgroup_from_mm(mm);
>  -	ret = charge_memcg(page, memcg, gfp_mask);
>  +	ret = charge_memcg(folio, memcg, gfp);
>   	css_put(&memcg->css);
>   
>   	return ret;
> @@@ -6906,20 -6909,17 +6899,17 @@@ static void uncharge_folio(struct foli
>   }
>   
>   /**
> -  * mem_cgroup_uncharge - Uncharge a folio.
>  - * __mem_cgroup_uncharge - uncharge a page
>  - * @page: page to uncharge
> ++ * __mem_cgroup_uncharge - Uncharge a folio.
>  + * @folio: Folio to uncharge.
>    *
>  - * Uncharge a page previously charged with __mem_cgroup_charge().
>  + * Uncharge a folio previously charged with mem_cgroup_charge().
>    */
> - void mem_cgroup_uncharge(struct folio *folio)
>  -void __mem_cgroup_uncharge(struct page *page)
> ++void __mem_cgroup_uncharge(struct folio *folio)
>   {
>   	struct uncharge_gather ug;
>   
> - 	if (mem_cgroup_disabled())
> - 		return;
> - 
>  -	/* Don't touch page->lru of any random page, pre-check: */
>  -	if (!page_memcg(page))
>  +	/* Don't touch folio->lru of any random page, pre-check: */
>  +	if (!folio_memcg(folio))
>   		return;
>   
>   	uncharge_gather_clear(&ug);
> @@@ -6932,19 -6932,16 +6922,16 @@@
>    * @page_list: list of pages to uncharge
>    *
>    * Uncharge a list of pages previously charged with
> -  * mem_cgroup_charge().
> +  * __mem_cgroup_charge().
>    */
> - void mem_cgroup_uncharge_list(struct list_head *page_list)
> + void __mem_cgroup_uncharge_list(struct list_head *page_list)
>   {
>   	struct uncharge_gather ug;
>  -	struct page *page;
>  +	struct folio *folio;
>   
> - 	if (mem_cgroup_disabled())
> - 		return;
> - 
>   	uncharge_gather_clear(&ug);
>  -	list_for_each_entry(page, page_list, lru)
>  -		uncharge_page(page, &ug);
>  +	list_for_each_entry(folio, page_list, lru)
>  +		uncharge_folio(folio, &ug);
>   	if (ug.memcg)
>   		uncharge_batch(&ug);
>   }

This is now a conflict between the folio tree and Linus' tree.

-- 
Cheers,
Stephen Rothwell