From patchwork Mon Nov 25 13:06:20 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 294036 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 23A912C00DE for ; Tue, 26 Nov 2013 04:02:05 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1VkzXn-0002wr-56; Mon, 25 Nov 2013 17:01:55 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1VkvtO-0006CC-Ij for kernel-team@lists.ubuntu.com; Mon, 25 Nov 2013 13:07:58 +0000 Received: from bl20-223-77.dsl.telepac.pt ([2.81.223.77] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1VkvtK-0003dL-0I; Mon, 25 Nov 2013 13:07:54 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.5 33/78] lib/scatterlist.c: don't flush_kernel_dcache_page on slab page Date: Mon, 25 Nov 2013 13:06:20 +0000 Message-Id: <1385384825-21681-34-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1385384825-21681-1-git-send-email-luis.henriques@canonical.com> References: <1385384825-21681-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 X-Mailman-Approved-At: Mon, 25 Nov 2013 17:01:53 +0000 Cc: Jens Axboe , Russell King - ARM Linux , Aaro Koskinen , Will Deacon , "James E.J. Bottomley" , FUJITA Tomonori , Tejun Heo , Andrew Morton , Linus Torvalds X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.26 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei commit 3d77b50c5874b7e923be946ba793644f82336b75 upstream. Commit b1adaf65ba03 ("[SCSI] block: add sg buffer copy helper functions") introduces two sg buffer copy helpers, and calls flush_kernel_dcache_page() on pages in SG list after these pages are written to. Unfortunately, the commit may introduce a potential bug: - Before sending some SCSI commands, kmalloc() buffer may be passed to block layper, so flush_kernel_dcache_page() can see a slab page finally - According to cachetlb.txt, flush_kernel_dcache_page() is only called on "a user page", which surely can't be a slab page. - ARCH's implementation of flush_kernel_dcache_page() may use page mapping information to do optimization so page_mapping() will see the slab page, then VM_BUG_ON() is triggered. Aaro Koskinen reported the bug on ARM/kirkwood when DEBUG_VM is enabled, and this patch fixes the bug by adding test of '!PageSlab(miter->page)' before calling flush_kernel_dcache_page(). Signed-off-by: Ming Lei Reported-by: Aaro Koskinen Tested-by: Simon Baatz Cc: Russell King - ARM Linux Cc: Will Deacon Cc: Aaro Koskinen Acked-by: Catalin Marinas Cc: FUJITA Tomonori Cc: Tejun Heo Cc: "James E.J. Bottomley" Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- lib/scatterlist.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 6096e89..8c2f278 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -419,7 +419,8 @@ void sg_miter_stop(struct sg_mapping_iter *miter) if (miter->addr) { miter->__offset += miter->consumed; - if (miter->__flags & SG_MITER_TO_SG) + if ((miter->__flags & SG_MITER_TO_SG) && + !PageSlab(miter->page)) flush_kernel_dcache_page(miter->page); if (miter->__flags & SG_MITER_ATOMIC) {