From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751442AbVJKJwW (ORCPT ); Tue, 11 Oct 2005 05:52:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751440AbVJKJwW (ORCPT ); Tue, 11 Oct 2005 05:52:22 -0400 Received: from gate.crashing.org ([63.228.1.57]:25224 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S1751442AbVJKJwV (ORCPT ); Tue, 11 Oct 2005 05:52:21 -0400 Subject: Re: [PATCH] ppc highmem fix From: Benjamin Herrenschmidt To: Paolo Galtieri Cc: Linus Torvalds , Andrew Morton , Linux Kernel In-Reply-To: <1128987529.16630.14.camel@playin.mvista.com> References: <1128986427.16630.6.camel@playin.mvista.com> <1128987529.16630.14.camel@playin.mvista.com> Content-Type: text/plain Date: Tue, 11 Oct 2005 19:38:55 +1000 Message-Id: <1129023535.17365.200.camel@gaston> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2005-10-10 at 16:38 -0700, Paolo Galtieri wrote: > On Mon, 2005-10-10 at 16:20 -0700, Paolo Galtieri wrote: > > I've noticed that the calculations for seg_size and nr_segs in > > __dma_sync_page_highmem() (arch/ppc/kernel/dma-mapping.c) are wrong. > > The incorrect calculations can result in either an oops or a panic when > > running fsck depending on the size of the partition. The problem with > > the > > seg_size calculation is that it can result in a negative number if size > > is offset > size. The problem with the nr_segs caculation is returns > > the > > wrong number of segments, e.g. it returns 1 when size is 200 and offset > > is 4095, when it should return 2 or more. > > > > Here is the patch to fix the problem. Looks good, should probably still make it to 2.6.14, Andrew, Linus ? (Paolo, can you send them a clean patch ?) Acked-by: Benjamin Herrenschmidt > > --- linux-2.6.14-rc3-git8/arch/ppc/kernel/dma-mapping.c 2005-10-10 > > 13:55:37.000000000 -0700 > > +++ linux-2.6.14/arch/ppc/kernel/dma-mapping.c 2005-10-10 > > 13:57:51.000000000 -0700 > > @@ -401,10 +401,10 @@ > > static inline void __dma_sync_page_highmem(struct page *page, > > unsigned long offset, size_t size, int direction) > > { > > - size_t seg_size = min((size_t)PAGE_SIZE, size) - offset; > > + size_t seg_size = min((size_t)(PAGE_SIZE - offset), size); > > size_t cur_size = seg_size; > > unsigned long flags, start, seg_offset = offset; > > - int nr_segs = PAGE_ALIGN(size + (PAGE_SIZE - offset))/PAGE_SIZE; > > + int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE; > > int seg_nr = 0; > > > > local_irq_save(flags); > > > > > > Paolo Galtieri (pgaltieri@mvista.com) > > > > I want to apologize in advance for the previous post. When I included > the patch inline I dropped the tabs :-(. Here is the correct patch with > tabs: > > --- linux-2.6.14-rc3-git8/arch/ppc/kernel/dma-mapping.c 2005-10-10 > 13:55:37.000000000 -0700 > +++ linux-2.6.14/arch/ppc/kernel/dma-mapping.c 2005-10-10 > 13:57:51.000000000 -0700 > @@ -401,10 +401,10 @@ > static inline void __dma_sync_page_highmem(struct page *page, > unsigned long offset, size_t size, int direction) > { > - size_t seg_size = min((size_t)PAGE_SIZE, size) - offset; > + size_t seg_size = min((size_t)(PAGE_SIZE - offset), size); > size_t cur_size = seg_size; > unsigned long flags, start, seg_offset = offset; > - int nr_segs = PAGE_ALIGN(size + (PAGE_SIZE - offset))/PAGE_SIZE; > + int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE; > int seg_nr = 0; > > local_irq_save(flags); > > Paolo > > - > 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/