From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hiroshi DOYU Subject: Re: dma_alloc_coherent fragmentation Date: Thu, 19 Mar 2009 08:42:48 +0200 (EET) Message-ID: <20090319.084248.183029086.Hiroshi.DOYU@nokia.com> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.nokia.com ([192.100.122.230]:20561 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751715AbZCSGnM (ORCPT ); Thu, 19 Mar 2009 02:43:12 -0400 In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: nm@ti.com Cc: linux-arm-kernel@lists.arm.linux.org.uk, nskamat@ti.com, linux-omap@vger.kernel.org, x00omar@ti.com, h-kanigeri2@ti.com, x0095840@ti.com, khilman@deeprootsystems.com, 2ameya@gmail.com Hi Nishant, From: "ext Kamat, Nishant" Subject: dma_alloc_coherent fragmentation Date: Wed, 18 Mar 2009 14:03:45 +0100 > Forwarding on behalf of Nishanth Menon: > > -----Original Message----- > From: Menon, Nishanth > Sent: Tuesday, March 17, 2009 8:17 AM > To: 'linux-arm-kernel@lists.arm.linux.org.uk' > Cc: Gupta, Ramesh; Kevin Hilman; linux-omap@vger.kernel.org; Ramirez Luna, Omar; Kanigeri, Hari; Ameya Palande; Guzman Lugo, Fernando; Ameya Palande > Subject: dma_alloc_coherent fragmentation > > Looping in linux-arm ML: > > Discussion Ref: [1](linux-omap mailing list) > While working with Linux OMAP kernel[2] we found that on allocating > 4 meg chunks using dma_alloc_coherent and de-allocating with > dma_free_coherent in a loop using a test driver[7], the memory is > getting fragmented as shown by Ameya's observation [3] finally > resulting in dump_stack due to lack of pages. What would happen with __GFP_RECLAIMABLE for dma_alloc_coherent()?