Re: [RFC PATCH 3/4] perf: Use vmalloc_to_folio()

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2023/8/22 4:20, Matthew Wilcox (Oracle) 写道:
> Eliminate a use of page->mapping by using vmalloc_to_folio() instead.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   include/linux/mm.h          | 5 +++++
>   kernel/events/ring_buffer.c | 4 ++--
>   2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 840bae5f23b6..7d84a2843193 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1134,6 +1134,11 @@ int region_intersects(resource_size_t offset, size_t size, unsigned long flags,
>   struct page *vmalloc_to_page(const void *addr);
>   unsigned long vmalloc_to_pfn(const void *addr);
>   
> +static inline struct folio *vmalloc_to_folio(const void *addr)
> +{
> +	return page_folio(vmalloc_to_page(addr));
> +}

Thanks a lot. This function is very wonderful. It is also what I need.

Zhu Yanjun

> +
>   /*
>    * Determine if an address is within the vmalloc range
>    *
> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
> index c73add132618..56939dc3bf33 100644
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -873,9 +873,9 @@ __perf_mmap_to_page(struct perf_buffer *rb, unsigned long pgoff)
>   
>   static void perf_mmap_unmark_page(void *addr)
>   {
> -	struct page *page = vmalloc_to_page(addr);
> +	struct folio *folio = vmalloc_to_folio(addr);
>   
> -	page->mapping = NULL;
> +	folio->mapping = NULL;
>   }
>   
>   static void rb_free_work(struct work_struct *work)