linux-kernel - Re: [PATCH v5 3/5] mm/readahead: Make space in struct file_ra

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

Message-ID: <20250611-mitleid-ablief-1e7f1f03394d@brauner>
Date: Wed, 11 Jun 2025 11:57:32 +0200
From: Christian Brauner <brauner@...nel.org>
To: Ryan Roberts <ryan.roberts@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, 
	"Matthew Wilcox (Oracle)" <willy@...radead.org>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Jan Kara <jack@...e.cz>, David Hildenbrand <david@...hat.com>, 
	Dave Chinner <david@...morbit.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Kalesh Singh <kaleshsingh@...gle.com>, Zi Yan <ziy@...dia.com>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	linux-mm@...ck.org
Subject: Re: [PATCH v5 3/5] mm/readahead: Make space in struct file_ra_state

On Mon, Jun 09, 2025 at 10:27:25AM +0100, Ryan Roberts wrote:
> We need to be able to store the preferred folio order associated with a
> readahead request in the struct file_ra_state so that we can more
> accurately increase the order across subsequent readahead requests. But
> struct file_ra_state is per-struct file, so we don't really want to
> increase it's size.
> 
> mmap_miss is currently 32 bits but it is only counted up to 10 *
> MMAP_LOTSAMISS, which is currently defined as 1000. So 16 bits should be
> plenty. Redefine it to unsigned short, making room for order as unsigned
> short in follow up commit.
> 
> Acked-by: David Hildenbrand <david@...hat.com>
> Reviewed-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---
>  include/linux/fs.h |  2 +-
>  mm/filemap.c       | 11 ++++++-----
>  2 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 05abdabe9db7..87e7d5790e43 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1052,7 +1052,7 @@ struct file_ra_state {
>  	unsigned int size;
>  	unsigned int async_size;
>  	unsigned int ra_pages;
> -	unsigned int mmap_miss;
> +	unsigned short mmap_miss;

Thanks for not making struct file grow!