From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id 471956B0033 for ; Thu, 14 Sep 2017 23:00:15 -0400 (EDT) Received: by mail-it0-f70.google.com with SMTP id u2so3745553itb.7 for ; Thu, 14 Sep 2017 20:00:15 -0700 (PDT) Received: from smtpproxy19.qq.com (smtpproxy19.qq.com. [184.105.206.84]) by mx.google.com with ESMTPS id d14si5636230oic.537.2017.09.14.20.00.10 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 14 Sep 2017 20:00:11 -0700 (PDT) From: Huacai Chen Subject: [PATCH V4 2/3] mm: dmapool: Align to ARCH_DMA_MINALIGN in non-coherent DMA mode Date: Fri, 15 Sep 2017 11:00:54 +0800 Message-Id: <1505444454-21321-1-git-send-email-chenhc@lemote.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Fuxin Zhang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huacai Chen , stable@vger.kernel.org In non-coherent DMA mode, kernel uses cache flushing operations to maintain I/O coherency, so the dmapool objects should be aligned to ARCH_DMA_MINALIGN. Otherwise, it will cause data corruption, at least on MIPS: Step 1, dma_map_single Step 2, cache_invalidate (no writeback) Step 3, dma_from_device Step 4, dma_unmap_single If a DMA buffer and a kernel structure share a same cache line, and if the kernel structure has dirty data, cache_invalidate (no writeback) will cause data lost. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen --- mm/dmapool.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/dmapool.c b/mm/dmapool.c index 4d90a64..2ac6f4a 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -140,6 +140,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, else if (align & (align - 1)) return NULL; + if (!plat_device_is_coherent(dev)) + align = max_t(size_t, align, dma_get_cache_alignment()); + if (size == 0) return NULL; else if (size < 4) -- 2.7.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org