Re: [PATCH v2] mm: swap: use fixed-size readahead during swapoff

From: "Huang\, Ying" <ying.huang@intel.com>
To: Andrea Righi <andrea.righi@canonical.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Minchan Kim <minchan@kernel.org>,
	Anchal Agarwal <anchalag@amazon.com>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mm: swap: use fixed-size readahead during swapoff
Date: Wed, 15 Apr 2020 15:44:08 +0800	[thread overview]
Message-ID: <87imi1yz07.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <20200415073239.GG810380@xps-13> (Andrea Righi's message of "Wed, 15 Apr 2020 09:32:39 +0200")

Andrea Righi <andrea.righi@canonical.com> writes:

>  mm/swapfile.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 9fd47e6f7a86..cb9eb517178d 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1944,7 +1944,9 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
>  		vmf.pmd = pmd;
>  		last_ra = atomic_read(&last_readahead_pages);
>  		atomic_set(&swapin_readahead_hits, last_ra);

You need to remove the above 2 lines firstly.

Best Regards,
Huang, Ying

> -		page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf);
> +		page = lookup_swap_cache(entry, vma, addr);
> +		if (!page)
> +			page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf);
>  		if (!page) {
>  			if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD)
>  				goto try_next;
>
> Thanks!
> -Andrea