From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752726AbdKWJmV (ORCPT ); Thu, 23 Nov 2017 04:42:21 -0500 Received: from mailgw01.mediatek.com ([210.61.82.183]:28927 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752007AbdKWJmQ (ORCPT ); Thu, 23 Nov 2017 04:42:16 -0500 X-UUID: 5a2d7504c809488582fe9743b9f62822-20171123 From: To: Christoph Hellwig , Marek Szyprowski , Robin Murphy CC: , , , , Miles Chen Subject: [PATCH v5] dma-debug: fix incorrect pfn calculation Date: Thu, 23 Nov 2017 17:42:09 +0800 Message-ID: <1511430129-4210-1-git-send-email-miles.chen@mediatek.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miles Chen dma-debug reports the following warning: [name:panic&]WARNING: CPU: 3 PID: 298 at kernel-4.4/lib/dma-debug.c:604 debug _dma_assert_idle+0x1a8/0x230() DMA-API: cpu touching an active dma mapped cacheline [cln=0x00000882300] CPU: 3 PID: 298 Comm: vold Tainted: G W O 4.4.22+ #1 Hardware name: MT6739 (DT) Call trace: [] dump_backtrace+0x0/0x1d4 [] show_stack+0x14/0x1c [] dump_stack+0xa8/0xe0 [] warn_slowpath_common+0xf4/0x11c [] warn_slowpath_fmt+0x60/0x80 [] debug_dma_assert_idle+0x1a8/0x230 [] wp_page_copy.isra.96+0x118/0x520 [] do_wp_page+0x4fc/0x534 [] handle_mm_fault+0xd4c/0x1310 [] do_page_fault+0x1c8/0x394 [] do_mem_abort+0x50/0xec I found that debug_dma_alloc_coherent() and debug_dma_free_coherent() assume that dma_alloc_coherent() always returns a linear address. However it's possible that dma_alloc_coherent() returns a non-linear address. In this case, page_to_pfn(virt_to_page(virt)) will return an incorrect pfn. If the pfn is valid and mapped as a COW page, we will hit the warning when doing wp_page_copy(). Fix this by calculating pfn for linear and non-linear addresses. Some changes are added to this patch according to Christoph's comment in patch v3 and a bugfix in patch v4: a. use normal if/else statement for better readability b. exclude non-linear and non-vmalloc addresses c. use virt_addr_valid() to check linear addresses Signed-off-by: Miles Chen --- lib/dma-debug.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/lib/dma-debug.c b/lib/dma-debug.c index ea4cc3d..4c08eb6 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -1495,14 +1495,22 @@ void debug_dma_alloc_coherent(struct device *dev, size_t size, if (!entry) return; + /* handle vmalloc and linear addresses */ + if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt)) + return; + entry->type = dma_debug_coherent; entry->dev = dev; - entry->pfn = page_to_pfn(virt_to_page(virt)); entry->offset = offset_in_page(virt); entry->size = size; entry->dev_addr = dma_addr; entry->direction = DMA_BIDIRECTIONAL; + if (is_vmalloc_addr(virt)) + entry->pfn = vmalloc_to_pfn(virt); + else + entry->pfn = page_to_pfn(virt_to_page(virt)); + add_dma_entry(entry); } EXPORT_SYMBOL(debug_dma_alloc_coherent); @@ -1513,13 +1521,21 @@ void debug_dma_free_coherent(struct device *dev, size_t size, struct dma_debug_entry ref = { .type = dma_debug_coherent, .dev = dev, - .pfn = page_to_pfn(virt_to_page(virt)), .offset = offset_in_page(virt), .dev_addr = addr, .size = size, .direction = DMA_BIDIRECTIONAL, }; + /* handle vmalloc and linear addresses */ + if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt)) + return; + + if (is_vmalloc_addr(virt)) + ref.pfn = vmalloc_to_pfn(virt); + else + ref.pfn = page_to_pfn(virt_to_page(virt)); + if (unlikely(dma_debug_disabled())) return; -- 1.9.1