Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161524AbbBDSai (ORCPT ); Wed, 4 Feb 2015 13:30:38 -0500 Received: from mga14.intel.com ([192.55.52.115]:48677 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932986AbbBDSae (ORCPT ); Wed, 4 Feb 2015 13:30:34 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,519,1418112000"; d="scan'208";a="680915239" Message-ID: <1423074632.9530.110.camel@schen9-desk2.jf.intel.com> Subject: Re: [PATCH] pci-dma: Fix x86 dma_alloc_coherent to fully clear all pages returned From: Tim Chen To: Sergei Shtylyov Cc: Jiri Slaby , "H. Peter Anvin" , Akinobu Mita , Mathias Nyman , Andi Kleen , Ingo Molnar , Andrew Morton , Marek Szyprowski , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, linux-usb@vger.kernel.org, stable Date: Wed, 04 Feb 2015 10:30:32 -0800 In-Reply-To: <54CFA836.6010309@cogentembedded.com> References: <1422647641.9530.2.camel@schen9-desk2.jf.intel.com> <54CBF1A0.9080005@cogentembedded.com> <1422654849.9530.8.camel@schen9-desk2.jf.intel.com> <54CF8374.80704@suse.cz> <54CFA836.6010309@cogentembedded.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.8.5 (3.8.5-2.fc19) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2203 Lines: 71 On Mon, 2015-02-02 at 19:39 +0300, Sergei Shtylyov wrote: > > > Hi, is this an open-coded version of PAGE_ALIGN? > > Yes, it appears so. :-) > > WBR, Sergei > Thanks for the suggestion by Jiri. I updated the patch to use PAGE_ALIGN below. Regards, Tim --->8--- From: Tim Chen Subject: [PATCH] pci-dma: Fix x86 dma_alloc_coherent to fully clear all pages returned Commit d92ef66c4f8f ("x86: make dma_alloc_coherent() return zeroed memory if CMA is enabled") changed the dma_alloc_coherent page clearance from using an __GFP_ZERO in page allocation to not setting the flag but doing an explicit memory clear at the end. However the memory clear only covered the memory size that was requested, but may not be up to the full extent of the last page, if the total pages returned exceed the memory size requested. This behavior has caused problem with XHCI and caused it to hang: kernel: xhci_hcd 0000:00:14.0: Stopped the command ring failed, maybe the host is dead kernel: xhci_hcd 0000:00:14.0: Abort command ring failed kernel: xhci_hcd 0000:00:14.0: HC died; cleaning up kernel: xhci_hcd 0000:00:14.0: Error while assigning device slot ID kernel: xhci_hcd 0000:00:14.0: Max number of devices this xHCI host supports is 64. Other drivers may have similar issue if it assumes that the pages allocated are completely zeroed. This patch ensures that the pages returned are fully cleared. Signed-off-by: Tim Chen Cc: stable@vger.kernel.org --- arch/x86/kernel/pci-dma.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index a25e202..3bdee55 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -125,6 +125,8 @@ again: return NULL; } + /* round up to full page size */ + size = PAGE_ALIGN(size); memset(page_address(page), 0, size); *dma_addr = addr; return page_address(page); -- 1.9.3 -- 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/