From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: SCSI breakage on non-cache coherent architectures Date: Mon, 19 Nov 2007 00:38:02 -0800 (PST) Message-ID: <20071119.003802.100741794.davem@davemloft.net> References: <1195450523.7022.37.camel@pasglop> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:52024 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752206AbXKSIiC (ORCPT ); Mon, 19 Nov 2007 03:38:02 -0500 In-Reply-To: <1195450523.7022.37.camel@pasglop> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: benh@kernel.crashing.org Cc: James.Bottomley@HansenPartnership.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, rmk@arm.linux.org.uk From: Benjamin Herrenschmidt Date: Mon, 19 Nov 2007 16:35:23 +1100 > I'm not sure what is the best way to fix that. Internally, I've done > some test whacking some ____cacheline_aligned in the scsi_cmnd data > structure to verify I no longer get random SLAB corruption when using my > USB but that significantly bloats the size of the structure on archs > such as ppc64 that don't need it and have a large cache line size. > > Unfortunately, I don't think there's any existing Kconfig symbol or arch > provided #define to tell us that we are on a non-coherent arch afaik > that could be used to make that conditional. > > Another option would be to kmalloc the buffer (wasn't it the case before > btw ?) but I suppose some people will scream at the idea due to how the > command pools are done... You could make a ____dma_cacheline_aligned and use that. It seems pretty reasonable.