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From:   NeilBrown <neilb@suse.de>
To:     Chuck Lever <chuck.lever@oracle.com>
Date:   Mon, 08 Feb 2021 10:42:08 +1100
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: releasing result pages in svc_xprt_release()
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On Fri, Feb 05 2021, Chuck Lever wrote:
>
> Baby steps.
>
> Because I'm perverse I started with bulk page freeing. In the course
> of trying to invent a new API, I discovered there already is a batch
> free_page() function called release_pages().
>
> It seems to work as advertised for pages that are truly no longer
> in use (ie RPC/RDMA pages) but not for pages that are still in flight
> but released (ie TCP pages).
>
> release_pages() chains the pages in the passed-in array onto a list
> by their page->lru fields. This seems to be a problem if a page
> is still in use.

But if a page is still in use, it is not put on the list.

		if (!put_page_testzero(page))
			continue;

NeilBrown

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