From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Fri, 9 Nov 2018 16:37:54 +0000 Subject: [PATCH 06/10] swiotlb: use swiotlb_map_page in swiotlb_map_sg_attrs In-Reply-To: <20181109074955.GA27489@lst.de> References: <20181008080246.20543-1-hch@lst.de> <20181008080246.20543-7-hch@lst.de> <20181109074955.GA27489@lst.de> Message-ID: <9922f377-ee87-ba36-8d28-26af0f7822e5@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 09/11/2018 07:49, Christoph Hellwig wrote: > On Tue, Nov 06, 2018 at 05:27:14PM -0800, John Stultz wrote: >> But at that point if I just re-apply "swiotlb: use swiotlb_map_page in >> swiotlb_map_sg_attrs", I reproduce the hangs. >> >> Any suggestions for how to further debug what might be going wrong >> would be appreciated! > > Very odd. In the end map_sg and map_page are defined to do the same > things to start with. The only real issue we had in this area was: > > "[PATCH v2] of/device: Really only set bus DMA mask when appropriate" > > so with current mainline + that you still see a problem, and if you > rever the commit we are replying to it still goes away? OK, after quite a bit of trying I have managed to provoke a similar-looking problem with straight 4.20-rc1 on my Juno board - so far my "reproducer" is to decompress a ~10GB .tar.xz off an external USB hard disk, wherein after somewhere between 5 minutes and half an hour or so it tends to falls over with xz choking on corrupt data and/or a USB error. From the presentation, this really smells like there's some corner in which we're either missing cache maintenance or doing it to the wrong address - I've not seen any issues with Juno's main PCIe-attached I/O, but the EHCI here is non-coherent (and 32-bit, so the bus_dma_mask thing doesn't matter) as are the HiKey UFS and SD controller. I'll keep digging... Robin.