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

From: Andrew Morton <[email-masked]>
Date: Wed, 25 Jul 2012 11:57:13 -0700

On Wed, 25 Jul 2012 09:35:03 +0200
Johannes Weiner <[email-masked]> wrote:

> As this is unlikely to reappear in this merge window, the conflict
> resolution is quite simple.  All that's needed is remove the 3 hunks
> from my patch that converted a user in Peter's patch to a new API.  I
> can resend the series if needed, but it's probably easier to just
> remove the hunks against mm/migrate.c::migrate_misplaced_page():
> 
> @@ -1519,10 +1512,9 @@ migrate_misplaced_page(struct page *page, struct mm_struct *mm, int node)
>  {
>  	struct page *oldpage = page, *newpage;
>  	struct address_space *mapping = page_mapping(page);
> -	struct mem_cgroup *mcg;
> +	struct mem_cgroup *memcg;
>  	unsigned int gfp;
>  	int rc = 0;
> -	int charge = -ENOMEM;
>  
>  	VM_BUG_ON(!PageLocked(page));
>  	VM_BUG_ON(page_mapcount(page));
> @@ -1556,12 +1548,7 @@ migrate_misplaced_page(struct page *page, struct mm_struct *mm, int node)
>  	if (!trylock_page(newpage))
>  		BUG();		/* new page should be unlocked!!! */
>  
> -	// XXX hnaz, is this right?
> -	charge = mem_cgroup_prepare_migration(page, newpage, &mcg, gfp);
> -	if (charge == -ENOMEM) {
> -		rc = charge;
> -		goto out;
> -	}
> +	mem_cgroup_prepare_migration(page, newpage, &memcg);
>  
>  	newpage->index = page->index;
>  	newpage->mapping = page->mapping;
> @@ -1581,11 +1568,9 @@ migrate_misplaced_page(struct page *page, struct mm_struct *mm, int node)
>  		page = newpage;
>  	}
>  
> +	mem_cgroup_end_migration(memcg, oldpage, newpage, !rc);
>  out:
> -	if (!charge)
> -		mem_cgroup_end_migration(mcg, oldpage, newpage, !rc);
> -
> -       if (oldpage != page)
> +	if (oldpage != page)
>                 put_page(oldpage);
>  
>  	if (rc) {

Yes, that worked out OK.

This means that if the above code reappears in linux-next or mainline,
the current copy of
mm-memcg-fix-compaction-migration-failing-due-to-memcg-limits.patch
will no longer update it, and I probably won't notice that omission.