Re: [PATCH] fix can_share_swap_page() when !CONFIG_SWAP

[Nick Piggin]

Hua Zhong wrote:

> Hi,
>
> can_share_swap_page() is used to check if the page has the last reference. This avoids allocating a new page for COW if it's the last page.
>
> However, if CONFIG_SWAP is not set, can_share_swap_page() is defined as 0, thus always causes a copy for the last COW page. The below simple patch fixes it.
>
> I'm not sure if it's the best fix. Maybe we should rename can_share_swap_page() and move it out of swapfile.c. Comments?

Looks like a good patch, nice catch. You should run it past Hugh but tend to
agree it would be nice to reuse the out of line can_share_swap_page, 
which would
fold beautifully with PageSwapCache a constant 0.

Nick
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