Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933699Ab1CXIZr (ORCPT ); Thu, 24 Mar 2011 04:25:47 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:41996 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932228Ab1CXIZm (ORCPT ); Thu, 24 Mar 2011 04:25:42 -0400 Date: Thu, 24 Mar 2011 08:25:21 +0000 From: Russell King - ARM Linux To: Nicolas Ferre Cc: dedekind1@gmail.com, "'linux-arm-kernel@lists.infradead.org'" , Linux Kernel list , Patrice VILCHEZ , Hong XU , Jean-Christophe PLAGNIOL-VILLARD , Andrew Victor , linux-mtd Subject: Re: Hit BUG_ON in dma-mapping.c:425 (RFC) Message-ID: <20110324082521.GB9844@n2100.arm.linux.org.uk> References: <4D24A108.2080609@atmel.com> <4D8AFE45.8050609@atmel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D8AFE45.8050609@atmel.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1099 Lines: 34 On Thu, Mar 24, 2011 at 04:18:13PM +0800, Nicolas Ferre wrote: > diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c > --- a/drivers/spi/atmel_spi.c > +++ b/drivers/spi/atmel_spi.c > @@ -647,6 +647,22 @@ static void atmel_spi_next_message(struct spi_master *master) > atmel_spi_next_xfer(master, msg); > } > > +static void *adjust_buffer_location(struct device *dev, void *buf) > +{ > + if (likely(buf < high_memory)) { > + return buf; > + } else { > + struct page *pg; > + > + pg = vmalloc_to_page(buf); > + if (pg == 0) { > + dev_err(dev, "failed to vmalloc_to_page\n"); > + return NULL; > + } > + return page_address(pg) + ((size_t)buf & ~PAGE_MASK); > + } > +} > + This really doesn't fix the problem. If the page is read or written via the vmalloc mapping, you'll have stale data. DMA to vmalloc areas is dodgy at best. -- 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/