Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933294AbcK3Jat (ORCPT ); Wed, 30 Nov 2016 04:30:49 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60392 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752376AbcK3J2K (ORCPT ); Wed, 30 Nov 2016 04:28:10 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John David Anglin , Helge Deller Subject: [PATCH 4.4 15/21] parisc: Fix race in pci-dma.c Date: Wed, 30 Nov 2016 10:27:31 +0100 Message-Id: <20161130092655.631318879@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161130092654.890709900@linuxfoundation.org> References: <20161130092654.890709900@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1534 Lines: 42 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: John David Anglin commit c0452fb9fb8f49c7d68ab9fa0ad092016be7b45f upstream. We are still troubled by occasional random segmentation faults and memory memory corruption on SMP machines. The causes quite a few package builds to fail on the Debian buildd machines for parisc. When gcc-6 failed to build three times in a row, I looked again at the TLB related code. I found a couple of issues. This is the first. In general, we need to ensure page table updates and corresponding TLB purges are atomic. The attached patch fixes an instance in pci-dma.c where the page table update was not guarded by the TLB lock. Tested on rp3440 and c8000. So far, no further random segmentation faults have been observed. Signed-off-by: John David Anglin Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- arch/parisc/kernel/pci-dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/parisc/kernel/pci-dma.c +++ b/arch/parisc/kernel/pci-dma.c @@ -95,8 +95,8 @@ static inline int map_pte_uncached(pte_t if (!pte_none(*pte)) printk(KERN_ERR "map_pte_uncached: page already exists\n"); - set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC)); purge_tlb_start(flags); + set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC)); pdtlb_kernel(orig_vaddr); purge_tlb_end(flags); vaddr += PAGE_SIZE;