From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Breuer Subject: Re: Hang: 2.6.32.4 sky2/DMAR (was [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync) Date: Thu, 28 Jan 2010 13:46:17 -0500 Message-ID: <4B61DB79.4080703@majjas.com> References: <20100120094103.GA6225@ff.dom.local> <4B58B217.8030001@majjas.com> <20100121204133.GB3085@del.dom.local> <4B59E7EB.3050605@majjas.com> <20100122215304.GA3105@del.dom.local> <4B5A2362.6000306@majjas.com> <20100122230605.GB3105@del.dom.local> <4B5A33D8.90501@majjas.com> <20100122234656.GC3105@del.dom.local> <4B5A39BD.8020305@majjas.com> <20100123232133.GA3487@del.dom.local> <4B605D1B.60402@majjas.com> <20100127085049.5b5048e9@nehalam> <4B60707F.1000608@majjas.com> <20100127095614.14313677@nehalam> <4B608128.7090607@majjas.com> <4B6089C7.4010803@majjas.com> <4B61ADF1.7060705@majjas.com> <4B61BEA4.1030905@majjas.com> <20100128090835.0d93e53a@nehalam> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7BIT Cc: Jarek Poplawski , David Miller , akpm@linux-foundation.org, flyboy@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Michael Chan , Don Fry , Francois Romieu , Matt Carlson To: Stephen Hemminger Return-path: In-reply-to: <20100128090835.0d93e53a@nehalam> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 1/28/2010 12:08 PM, Stephen Hemminger wrote: > On Thu, 28 Jan 2010 11:43:16 -0500 > Michael Breuer wrote: > > >> Update: I played with dma-debug. Was being disabled due to lack of >> memory. I forced it back on while pumping traffic through and got this: >> Jan 28 11:39:30 mail kernel: ------------[ cut here ]------------ >> Jan 28 11:39:30 mail kernel: WARNING: at lib/dma-debug.c:902 >> check_sync+0xc1/0x43f() >> Jan 28 11:39:30 mail kernel: Hardware name: System Product Name >> Jan 28 11:39:30 mail kernel: sky2 0000:06:00.0: DMA-API: device driver >> tries to sync DMA memory it has not allocated [device >> > This test in dma-debug is bogus. Because the debug code matches > dma based on address and size; and is perfectly valid to sync a value > less than size. This is the patch I sent earlier, it isn't 100% > correct but it will let you keep testing > .................................... > > > This should fix the dma-debug API code (and documentation), to > avoid false positives when sync is done on a partial map. > > Signed-off-by: Stephen Hemminger > > --- a/Documentation/DMA-API.txt 2010-01-20 15:17:01.390143729 -0800 > +++ b/Documentation/DMA-API.txt 2010-01-20 15:18:48.967875255 -0800 > @@ -377,9 +377,10 @@ void > pci_dma_sync_sg(struct pci_dev *hwdev, struct scatterlist *sg, > int nelems, int direction) > > -Synchronise a single contiguous or scatter/gather mapping. All the > -parameters must be the same as those passed into the single mapping > -API. > +Synchronise a single contiguous or scatter/gather mapping. The > +device and handle must be the same as those passed into the single mapping > +API. The size can be less than the original mapping if only part > +of the mapping needs to be accessed. > > Notes: You must do this: > > --- a/lib/dma-debug.c 2010-01-20 15:22:55.919519883 -0800 > +++ b/lib/dma-debug.c 2010-01-20 15:26:31.648895638 -0800 > @@ -285,11 +285,9 @@ static struct dma_debug_entry *hash_buck > } > > /* > - * If we have multiple matches but no perfect-fit, just return > - * NULL. > + * If we have multiple matches but no perfect-fit > + * return best value and let caller deal with it. > */ > - ret = (matches == 1) ? ret : NULL; > - > return ret; > } > > Ok - applied. Noise gone... however I'm not sure whether I'll be able to keep dma-debug going long enough to catch anything. num_free_entries keeps dropping... looks like entries are not freed. I'm running with a huge number for now & sky2 as the driver filter. Is there a reason that entries wouldn't be unmapped, or is dma-debug.c just not processing the unmap correctly?