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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
References: <20200413111810.GA801367@xps-13>
        <87a73f7d71.fsf@yhuang-dev.intel.com> <20200413133150.GA810380@xps-13>
        <87wo6i6efn.fsf@yhuang-dev.intel.com> <20200414130520.GF810380@xps-13>
        <87v9m1zd83.fsf@yhuang-dev.intel.com> <20200415073239.GG810380@xps-13>
Date:   Wed, 15 Apr 2020 15:44:08 +0800
In-Reply-To: <20200415073239.GG810380@xps-13> (Andrea Righi's message of "Wed,
        15 Apr 2020 09:32:39 +0200")
Message-ID: <87imi1yz07.fsf@yhuang-dev.intel.com>
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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