linux-kernel - Re: [PATCH] memory_hotplug: always initialize pageblock bitmap.

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 for Android: free password hash cracker in your pocket

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

Date:	Fri, 9 May 2008 15:39:10 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Heiko Carstens <heiko.carstens@...ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Whitcroft <apw@...dowen.org>,
	Dave Hansen <haveblue@...ibm.com>,
	Gerald Schaefer <gerald.schaefer@...ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] memory_hotplug: always initialize pageblock bitmap.

On Fri, 9 May 2008 08:06:09 +0200
Heiko Carstens <heiko.carstens@...ibm.com> wrote:

> From: Heiko Carstens <heiko.carstens@...ibm.com>
> 
> Trying to online a new memory section that was added via memory hotplug
> sometimes results in crashes when the new pages are added via
> __free_page. Reason for that is that the pageblock bitmap isn't
> initialized and hence contains random stuff.

Hmm, curious. In my understanding, memmap_init_zone() initializes it.

 __add_pages()
	-> __add_section()
		-> sparse-add_one_section() // allocate usemap
		-> __add_zone()
			-> memmap_init_zone() // reset pageblock's bitmap 

Can't memmap_init_zone() does proper initialization ?
........................
Ah, ok. I see. grow_zone_span() is not called at __add_zone(), then,
memmap_init_zone() doesn't initialize usemap because memmap is not in zone's
range.

Recently, I added a check "zone's start_pfn < pfn < zone's end"
to memmap_init_zone()'s usemap initialization for !SPARSEMEM case bug FIX.
(and I think the fix itself is sane.)

How about calling grow_pgdat_span()/grow_zone_span() from __add_zone() ?

Thanks,
-Kame

--
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/