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: <20130123014959.GB2723@blaptop>
Date:	Wed, 23 Jan 2013 10:49:59 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	paul.szabo@...ney.edu.au
Cc:	linux-mm@...ck.org, 695182@...s.debian.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Subtract min_free_kbytes from dirtyable memory

On Mon, Jan 21, 2013 at 02:15:49PM +1100, paul.szabo@...ney.edu.au wrote:
> When calculating amount of dirtyable memory, min_free_kbytes should be
> subtracted because it is not intended for dirty pages.

So what's the effect for user?
It would be better to include that in description if possible.

> 
> Using an "extern int" because that is the only interface to some such
> sysctl values.
> 
> (This patch does not solve the PAE OOM issue.)
> 
> Paul Szabo   psz@...hs.usyd.edu.au   http://www.maths.usyd.edu.au/u/psz/
> School of Mathematics and Statistics   University of Sydney    Australia
> 
> Reported-by: Paul Szabo <psz@...hs.usyd.edu.au>
> Reference: http://bugs.debian.org/695182
> Signed-off-by: Paul Szabo <psz@...hs.usyd.edu.au>
> 
> --- mm/page-writeback.c.old	2012-12-06 22:20:40.000000000 +1100
> +++ mm/page-writeback.c	2013-01-21 13:57:05.000000000 +1100
> @@ -343,12 +343,16 @@
>  unsigned long determine_dirtyable_memory(void)
>  {
>  	unsigned long x;
> +	extern int min_free_kbytes;
>  
>  	x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
>  
>  	if (!vm_highmem_is_dirtyable)
>  		x -= highmem_dirtyable_memory(x);
>  
> +	/* Subtract min_free_kbytes */
> +	x -= min(x, min_free_kbytes >> (PAGE_SHIFT - 10));

It seems you saw old kernel.
Current kernel includes following logic.

static unsigned long global_dirtyable_memory(void)
{
        unsigned long x;

        x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
        x -= min(x, dirty_balance_reserve);

        if (!vm_highmem_is_dirtyable)
                x -= highmem_dirtyable_memory(x);

        return x + 1;   /* Ensure that we never return 0 */
}

And dirty_lanace_reserve already includes high_wmark_pages.
Look at calculate_totalreserve_pages.

So I think we don't need this patch.
Thanks.

> +
>  	return x + 1;	/* Ensure that we never return 0 */
>  }
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@...ck.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>

-- 
Kind regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ