linux-kernel - Re: [v5 PATCH 2/2] mm: swap: add comment for swap_vma

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Message-ID: <87imz5tb04.fsf@yhuang-dev.intel.com>
Date:   Fri, 04 Jan 2019 10:25:15 +0800
From:   "Huang\, Ying" <ying.huang@...el.com>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     <tim.c.chen@...el.com>, <minchan@...nel.org>,
        <daniel.m.jordan@...cle.com>, <akpm@...ux-foundation.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [v5 PATCH 2/2] mm: swap: add comment for swap_vma_readahead

Yang Shi <yang.shi@...ux.alibaba.com> writes:

> swap_vma_readahead()'s comment is missed, just add it.
>
> Cc: Huang Ying <ying.huang@...el.com>
> Cc: Tim Chen <tim.c.chen@...el.com>
> Cc: Minchan Kim <minchan@...nel.org>
> Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>

Thank!

Reviewed-by: "Huang, Ying" <ying.huang@...el.com>

Best Regards,
Huang, Ying

> ---
> v5: Fixed the comments per Ying Huang
>
>  mm/swap_state.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 78d500e..c8730d7 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -523,7 +523,7 @@ static unsigned long swapin_nr_pages(unsigned long offset)
>   * This has been extended to use the NUMA policies from the mm triggering
>   * the readahead.
>   *
> - * Caller must hold down_read on the vma->vm_mm if vmf->vma is not NULL.
> + * Caller must hold read mmap_sem if vmf->vma is not NULL.
>   */
>  struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
>  				struct vm_fault *vmf)
> @@ -698,6 +698,20 @@ static void swap_ra_info(struct vm_fault *vmf,
>  	pte_unmap(orig_pte);
>  }
>  
> +/**
> + * swap_vma_readahead - swap in pages in hope we need them soon
> + * @entry: swap entry of this memory
> + * @gfp_mask: memory allocation flags
> + * @vmf: fault information
> + *
> + * Returns the struct page for entry and addr, after queueing swapin.
> + *
> + * Primitive swap readahead code. We simply read in a few pages whoes
> + * virtual addresses are around the fault address in the same vma.
> + *
> + * Caller must hold read mmap_sem if vmf->vma is not NULL.
> + *
> + */
>  static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
>  				       struct vm_fault *vmf)
>  {