linux-kernel - Re: [PATCH 4/7] mm: shmem: extend shmem_partial_swap

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Message-ID: <qlk2dpg2fmro5vzjks45ciwt3qk6nzlurfmlqnjr4ecskgg7ln@w5ba55tgtcsb>
Date: Mon, 10 Jun 2024 14:53:22 +0000
From: Daniel Gomez <da.gomez@...sung.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
CC: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"hughd@...gle.com" <hughd@...gle.com>, "willy@...radead.org"
	<willy@...radead.org>, "david@...hat.com" <david@...hat.com>,
	"wangkefeng.wang@...wei.com" <wangkefeng.wang@...wei.com>,
	"chrisl@...nel.org" <chrisl@...nel.org>, "ying.huang@...el.com"
	<ying.huang@...el.com>, "21cnbao@...il.com" <21cnbao@...il.com>,
	"ryan.roberts@....com" <ryan.roberts@....com>, "shy828301@...il.com"
	<shy828301@...il.com>, "ziy@...dia.com" <ziy@...dia.com>,
	"ioworker0@...il.com" <ioworker0@...il.com>, Pankaj Raghav
	<p.raghav@...sung.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] mm: shmem: extend shmem_partial_swap_usage() to
 support large folio swap

Hi Baolin,
On Thu, Jun 06, 2024 at 07:58:54PM +0800, Baolin Wang wrote:
> To support shmem large folio swapout in the following patches, using
> xa_get_order() to get the order of the swap entry to calculate the swap
> usage of shmem.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
>  mm/shmem.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index eefdf5c61c04..0ac71580decb 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -865,13 +865,16 @@ unsigned long shmem_partial_swap_usage(struct address_space *mapping,
>  	struct page *page;
>  	unsigned long swapped = 0;
>  	unsigned long max = end - 1;
> +	int order;
>  
>  	rcu_read_lock();
>  	xas_for_each(&xas, page, max) {
>  		if (xas_retry(&xas, page))
>  			continue;
> -		if (xa_is_value(page))
> -			swapped++;
> +		if (xa_is_value(page)) {
> +			order = xa_get_order(xas.xa, xas.xa_index);
> +			swapped += 1 << order;

I'd get rid of order and simply do:

	swapped += 1UL << xa_get_order()


> +		}
>  		if (xas.xa_index == max)
>  			break;
>  		if (need_resched()) {
> -- 
> 2.39.3
>