Re: [PATCH v2 3/3] NFS: Fix a memory leak in nfs_readdir

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 01 Dec 2010 18:21:16 -0500
Trond Myklebust <Trond.Myklebust@netapp.com> wrote:

> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -108,6 +108,10 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
>  	clear_page_mlock(page);
>  	remove_from_page_cache(page);
>  	ClearPageMappedToDisk(page);
> +
> +	if (mapping->a_ops->freepage)
> +		mapping->a_ops->freepage(page);
> +
>  	page_cache_release(page);	/* pagecache ref */
>  	return 0;
>  }

So here we're assuming that `mapping' was pinned by other means.

Fair enough, although subtle.  Even drop_pagecache_sb() got it right ;)

> @@ -390,6 +394,10 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
>  	__remove_from_page_cache(page);
>  	spin_unlock_irq(&mapping->tree_lock);
>  	mem_cgroup_uncharge_cache_page(page);
> +
> +	if (mapping->a_ops->freepage)
> +		mapping->a_ops->freepage(page);
> +
>  	page_cache_release(page);	/* pagecache ref */
>  	return 1;
>  failed:

And here.