Re: [v4 PATCH 2/2] mm: swap: add comment for swap_vma_readahead
From: Huang\, Ying
Date: Thu Jan 03 2019 - 02:41:12 EST
Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> writes:
> swap_vma_readahead()'s comment is missed, just add it.
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Cc: Tim Chen <tim.c.chen@xxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
> mm/swap_state.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 78d500e..dd8f698 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -698,6 +698,23 @@ static void swap_ra_info(struct vm_fault *vmf,
> + * swap_vm_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.
> + *
> + * This has been extended to use the NUMA policies from the mm triggering
> + * the readahead.
What is this? I know you copy it from swap_cluster_readahead(), but we
have only one mm for vma readahead.
> + * Caller must hold down_read on the vma->vm_mm if vmf->vma is not NULL.
Better to make it explicit that your are talking about mmap_sem?
> + *
> + */
> static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
> struct vm_fault *vmf)