From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932208AbbA3TyG (ORCPT ); Fri, 30 Jan 2015 14:54:06 -0500 Received: from mga01.intel.com ([192.55.52.88]:20045 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757402AbbA3TyE (ORCPT ); Fri, 30 Jan 2015 14:54:04 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,493,1418112000"; d="scan'208";a="678731793" Message-ID: <1422647641.9530.2.camel@schen9-desk2.jf.intel.com> Subject: [PATCH] pci-dma: Fix x86 dma_alloc_coherent to fully clear all pages returned From: Tim Chen To: "H. Peter Anvin" , Akinobu Mita , Mathias Nyman Cc: Andi Kleen , Ingo Molnar , Andrew Morton , Marek Szyprowski , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, linux-usb@vger.kernel.org Date: Fri, 30 Jan 2015 11:54:01 -0800 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 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 and froze usb: 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 --- 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..534470f 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 = (((size-1) >> PAGE_SHIFT) + 1) * PAGE_SIZE; memset(page_address(page), 0, size); *dma_addr = addr; return page_address(page); -- 1.9.3