From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bryan Holty Subject: Re: [PATCH] scsi: properly count the number of pages in scsi_req_map_sg() Date: Thu, 23 Mar 2006 10:51:51 -0600 Message-ID: <200603231051.51519.lgeek@frontiernet.net> References: <20060321083830.GA2364@localdomain> <20060321161912.GA32051@localdomain> <20060323145203.GA13637@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20060323145203.GA13637@infradead.org> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Dan Aloni , James Bottomley , linux-scsi , Linux Kernel List , brking@us.ibm.com, dror@xiv.co.il List-Id: linux-scsi@vger.kernel.org On Thursday 23 March 2006 08:52, Christoph Hellwig wrote: > On Tue, Mar 21, 2006 at 06:19:12PM +0200, Dan Aloni wrote: > > These scatterlists can be generated using the sg driver. Though I am > > actually running a customized version of the sg driver, it seems the > > conversion from a userspace array of sg_iovec_t to scatterlist stays > > the same and also applies to the original driver (see > > st_map_user_pages()). > > What kernel version did you reproduce this with? Since 2.6.16 sg should > obey all request size/alingment limitations. If not that's a bug in > scsi_execute_async and it's helpers and should be fixed there. > - > 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/ I am able to reproduce this with 2.6.16-rc5 - 2.6.16. There is a problem in scsi_req_map_sg which is called by scsi_execute_async. Currently, scsi_req_map_sg assumes every sgl entry is page aligned. It will cause later slab corruption by under-allocating the number of bio entries if sgl[0].offset + sgl[last].length > PAGE_SIZE. Dan pointed this out, and I have submitted a patch that I believe correctly fixes the issue. Just waiting for some feedback. -- Bryan Holty