linux-kernel - Re: [PATCH] hibernate / memory hotplug: always use for_each_populated

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: <4A70309A.3030304@de.ibm.com>
Date:	Wed, 29 Jul 2009 13:20:58 +0200
From:	Gerald Schaefer <gerald.schaefer@...ibm.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Nigel Cunningham <ncunningham@...a.org.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Yasunori Goto <y-goto@...fujitsu.com>,
	Nick Piggin <npiggin@...e.de>, linux-mm@...ck.org
Subject: Re: [PATCH] hibernate / memory hotplug: always use for_each_populated_zone()

Rafael J. Wysocki wrote:
>>> So it looks like checking for pfn_valid() and afterwards checking
>>> for PG_Reserved (?) might give what one would expect.
>> I think so, too. If memory is offline, PG_reserved is always set.
>>
>> In general, it's expected that "page is contiguous in MAX_ORDER range"
>> and no memory holes in MAX_ORDER. In most case, PG_reserved is checked
>> for skipping not-existing memory.
> 
> PG_reserved is also set for kernel text, at least on some architectures, and
> for some other areas that we want to save.

How about checking for PG_reserved && ZONE_MOVABLE? I think we don't
have any special cases for PG_reserved inside ZONE_MOVABLE, but I'm not
sure if this is true for all architectures and NUMA systems.

If this would work, it could be a simple way to determine which hotplug
memory should be saved.

--
Regards,
Gerald
--
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/