Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934362AbXHLMXo (ORCPT ); Sun, 12 Aug 2007 08:23:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758126AbXHLMXf (ORCPT ); Sun, 12 Aug 2007 08:23:35 -0400 Received: from ug-out-1314.google.com ([66.249.92.172]:48145 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757422AbXHLMXe (ORCPT ); Sun, 12 Aug 2007 08:23:34 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:date:from:to:cc:subject:message-id:references:mime-version:content-type:content-disposition:in-reply-to:user-agent; b=ZIj9iD5+ePS5aVZSJKs7tnaLpGv142VuDQ4sj72D8pEVX7O+85pm23RYOVtATPvP129wUggVeUgnrSg0+UhUkj0n4DHwSyO44N/03YSN1jY4dDtaNeNotq24vYqPh2h47HQnLmhckRVMZDa7/GAhSAG3AqUAahDTc+mPmxASg2U= Date: Sun, 12 Aug 2007 16:23:20 +0400 From: Cyrill Gorcunov To: Balbir Singh Cc: Andrew Morton , linux-kernel , Fengguang Wu Subject: Re: [BUGFIX] NULL pointer dereference in __vm_enough_memory() Message-ID: <20070812122320.GA15501@cvg> References: <386838491.27058@ustc.edu.cn> <661de9470708110730r1267bdfdp1e76546e11b64f78@mail.gmail.com> <20070811100015.2417788e.akpm@linux-foundation.org> <46BDF965.3050402@linux.vnet.ibm.com> <20070812054831.GB8992@mail.ustc.edu.cn> <386909088.16432@ustc.edu.cn> <46BED20C.308@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46BED20C.308@linux.vnet.ibm.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1693 Lines: 44 [Balbir Singh - Sun, Aug 12, 2007 at 02:55:32PM +0530] | WU Fengguang wrote: | > On Sun, Aug 12, 2007 at 01:48:31PM +0800, WU Fengguang wrote: | >> On Sat, Aug 11, 2007 at 11:31:09PM +0530, Balbir Singh wrote: | >>> Andrew Morton wrote: | >>>> On Sat, 11 Aug 2007 20:00:12 +0530 "Balbir Singh" wrote: | >>>>> Shouldn't we just not stop vm accounting for kernel threads? | >>>>> | >>>> Could be. It'd help heaps if we knew which patch in -mm caused | >>>> this, but from a quick peek it seems to me that mainline should be | >>>> vulnerable as well. | >>> Thats a valid point. It would be interesting to see what the overcommit | >>> setting was, when the panic occurred. | >> FYI, I do have nondefault overcommit settings: | >> | >> vm.overcommit_memory = 2 | >> vm.lowmem_reserve_ratio = 1 1 | > | > Yes, the bug disappears when changing to default overcommit_memory! | > | | Great! So the problem might have existed for some time, but we never | saw it due to default over commit values? Were you using these values | for over commit even before? | | -- | Warm Regards, | Balbir Singh | Linux Technology Center | IBM, ISTL So the problem is that __vm_enough_memory is just _not_ capable to be called from a thread with OVERCOMMIT_NEVER and Fengguang's patch does fix it. The scenario Fengguang show us is growing from keventd that starts a new user task. So Fengguang's patch seems right to me ;) Cyrill - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/