From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: rcar_sata DMA warnings on Salvator-X Date: Tue, 1 Mar 2016 12:12:18 -0500 Message-ID: <20160301171218.GH3965@htj.duckdns.org> References: <20160225214036.GI6092@mtj.duckdns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-renesas-soc-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Vladimir Barinov , "linux-ide@vger.kernel.org" , linux-renesas-soc@vger.kernel.org, dmaengine@vger.kernel.org, Harvey Hunt List-Id: linux-ide@vger.kernel.org Hello, On Mon, Feb 29, 2016 at 02:44:16PM +0100, Geert Uytterhoeven wrote: > sata_rcar ee300000.sata: DMA-API: cpu touching an active dma mapped > cacheline [cln=0x000000000090ff40] > ------------[ cut here ]------------ > WARNING: at lib/dma-debug.c:604 > Modules linked in: > > CPU: 2 PID: 329 Comm: udevd Not tainted ... > [] debug_dma_assert_idle+0x180/0x1d0 > [] wp_page_copy.isra.109+0xfc/0x57c > [] handle_mm_fault+0x125c/0x1300 > [] do_page_fault+0x184/0x328 > [] do_mem_abort+0x40/0x9c So, somehow udev has mmapped a page which is dma mapped and trying to falut that in? > Mapped at: > [] dma_entry_alloc+0x98/0xac > [] debug_dma_alloc_coherent+0x48/0xe0 > [] dmam_alloc_coherent+0xa8/0xf8 > [] ata_bmdma_port_start+0x40/0x5c > [] ata_host_start+0xf8/0x19c And that region was originally allocated by ata_bmdma_port_start()? The only thing which gets allocated there is the PRD table which is the scatter-gather list for the DMA engine and has no reason to be ever accessed from userland. Any chance you can find out what udev is doing at that point? Thanks. -- tejun