linux-kernel - Re: [PATCH] sys_getppid oopses on debug kernel (v2)

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Date:	Tue, 08 Aug 2006 09:09:21 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	Kirill Korotaev <dev@...ru>
Cc:	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	alan@...rguk.ukuu.org.uk, muli@...ibm.com, B.Steinbrink@....de,
	stable@...nel.org
Subject: Re: [PATCH] sys_getppid oopses on debug kernel (v2)

On Tue, 2006-08-08 at 19:50 +0400, Kirill Korotaev wrote:
> sys_getppid() optimization can access a freed memory.
> On kernels with DEBUG_SLAB turned ON, this results in Oops.
> As Dave Hansen noted, this optimization is also unsafe
> for memory hotplug. 

Yeah, I just tried coding up something to do a seqlock to note when
tasks are freed, but it doesn't work.  Unless somebody is really going
crazy with getppid() on a very large system, this should be just fine.

-- Dave


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