linux-kernel - Re: [PATCH -next v2] include/linux/mm.h: move nr_free_buffer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <YRkzKZ7yvKlCehR9@casper.infradead.org>
Date:   Sun, 15 Aug 2021 16:30:49 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Mianhan Liu <liumh1@...nghaitech.edu.cn>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH -next v2] include/linux/mm.h: move nr_free_buffer_pages
 from swap.h to mm.h

On Sun, Aug 15, 2021 at 07:50:57PM +0800, Mianhan Liu wrote:
> nr_free_buffer_pages could be exposed through mm.h instead of swap.h.
> The advantage of this change is that it can reduce the obsolete includes.
> For example, net/ipv4/tcp.c wouldn't need swap.h any more since it has
> already included mm.h.
> Moreover, after preprocessing all the files that use nr_free_buffer_pages,
> it turns out that those files have already included mm.h.
> Thus, we can move nr_free_buffer_pages from swap.h to mm.h safely. This change
> will not affect the compilation of other files.

In general, we're trying to move in the other direction; move things out
of mm.h and reduce the number of files which include mm.h.  That said,
I don't see what nr_free_buffer_pages() has to do with the rest of
swap.h, so I'm OK with moving this over.

That said, there are a number of other files which should have swap.h
removed.  eg:

drivers/mmc/core/mmc_test.c:#include <linux/swap.h>             /* For nr_free_buffer_pages() */

and it would be good to check the other files which use
nr_free_buffer_pages() to see if they can have swap.h removed too.

> +++ b/include/linux/mm.h
> @@ -871,6 +871,7 @@ void put_pages_list(struct list_head *pages);
>  void split_page(struct page *page, unsigned int order);
>  void folio_copy(struct folio *dst, struct folio *src);
>  
> +extern unsigned long nr_free_buffer_pages(void);

Please remove the 'extern' while you're moving this.

> +++ b/net/ipv4/tcp.c

If you're interested in cleaning up the headers, it'd be nice if less
of the networking code depended on pagemap.h ...