linux-kernel - Re: [RFC PATCH 3/4] mm: add zbud flag to page flags

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]

Date:	Thu, 08 Aug 2013 09:26:34 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Dave Hansen <dave.hansen@...el.com>
Cc:	Seth Jennings <sjenning@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [RFC PATCH 3/4] mm: add zbud flag to page flags

Hi,

On wto, 2013-08-06 at 09:58 -0700, Dave Hansen wrote:
> On 08/05/2013 11:42 PM, Krzysztof Kozlowski wrote:
> > +#ifdef CONFIG_ZBUD
> > +	/* Allocated by zbud. Flag is necessary to find zbud pages to unuse
> > +	 * during migration/compaction.
> > +	 */
> > +	PG_zbud,
> > +#endif
> 
> Do you _really_ need an absolutely new, unshared page flag?
> The zbud code doesn't really look like it uses any of the space in
> 'struct page'.
> 
> I think you could pretty easily alias PG_zbud=PG_slab, then use the
> page->{private,slab_cache} (or some other unused field) in 'struct page'
> to store a cookie to differentiate slab and zbud pages.

How about using page->_mapcount with negative value (-129)? Just like
PageBuddy()?


Best regards,
Krzysztof

--
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/