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From: Ingo Molnar <mingo@elte.hu>
To: Tony Battersby <tonyb@cybernetics.com>
Cc: linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Suresh Siddha <suresh.b.siddha@intel.com>,
	arjan@linux.intel.com, venkatesh.pallipadi@intel.com,
	jeremy@goop.org
Subject: Re: DEBUG_PAGEALLOC + order-10 alloc/free_pages = lockup
Date: Fri, 26 Dec 2008 10:48:57 +0100	[thread overview]
Message-ID: <20081226094857.GP27747@elte.hu> (raw)
In-Reply-To: <49513E33.5050001@cybernetics.com>


* Tony Battersby <tonyb@cybernetics.com> wrote:

> An order-10 alloc_pages followed by free_pages with DEBUG_PAGEALLOC
> causes a lockup during subsequent memory allocations.  Order-9 and lower
> do not trigger the problem.  This problem was introduced in 2.6.25-rc1
> and fixed in 2.6.28-rc1.  Even though the bug is now fixed, I am
> reporting it because:
> 
> 1) I am not sure that anyone ever realized that the bug existed.

Correct.

> 2) I want to make sure that the bug is really fixed and not just hidden
>    from view.

i think it got hidden. Apparently splitting up a large kernel linear page 
in IRQ context has a bug. I dont see it immediately what it could be - 
Thomas, Suresh, do you have any ideas?

> 3) To see if anyone thinks that the fix should be included in
>    2.6.27 -stable.

if 0b8fdcbcd287a1fbe66817491e6149841ae25705 applies cleanly to .27 -stable 
then i'd agree it should be added. If there's lots of dependencies then 
maybe not.

	Ingo

  reply	other threads:[~2008-12-26  9:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-23 19:38 DEBUG_PAGEALLOC + order-10 alloc/free_pages = lockup Tony Battersby
2008-12-26  9:48 ` Ingo Molnar [this message]
2008-12-26  9:55   ` Arjan van de Ven
2008-12-29 14:30     ` Tony Battersby

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