linux-kernel - Re: [RFC 3/8] shmem: account for high order folios

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Date:   Fri, 21 Apr 2023 23:46:58 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     hughd@...gle.com, akpm@...ux-foundation.org, brauner@...nel.org,
        djwong@...nel.org, p.raghav@...sung.com, da.gomez@...sung.com,
        a.manzanares@...sung.com, dave@...olabs.net, yosryahmed@...gle.com,
        keescook@...omium.org, hare@...e.de, kbusch@...nel.org,
        patches@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC 3/8] shmem: account for high order folios

On Fri, Apr 21, 2023 at 02:43:55PM -0700, Luis Chamberlain wrote:
> -		if (xa_is_value(page))
> -			swapped++;
> +		if (xa_is_value(folio))
> +			swapped+=(folio_nr_pages(folio));

			swapped += folio_nr_pages(folio);

>  			if (xa_is_value(folio)) {
> +				long swaps_freed = 0;
>  				if (unfalloc)
>  					continue;
> -				nr_swaps_freed += !shmem_free_swap(mapping,
> -							indices[i], folio);
> +				swaps_freed = folio_nr_pages(folio);

Why initialise it to 0 when you're about to set it to folio_nr_pages()?

> +				if (!shmem_free_swap(mapping, indices[i], folio)) {
> +					if (swaps_freed > 1)
> +						pr_warn("swaps freed > 1 -- %lu\n", swaps_freed);

Debug code that escaped into this patch?

> -		info->swapped++;
> +		info->swapped+=folio_nr_pages(folio);

Same comment as earlier.

> -	info->alloced--;
> -	info->swapped--;
> +	info->alloced-=num_swap_pages;
> +	info->swapped-=num_swap_pages;

Spacing

> -	info->swapped--;
> +	info->swapped-= folio_nr_pages(folio);

Spacing.