From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vikram Mulukutla Subject: [PATCH] tracing: Fix unmapping loop in tracing_mark_write Date: Wed, 17 Dec 2014 18:50:56 -0800 Message-ID: <1418871056-6614-1-git-send-email-markivx@codeaurora.org> Return-path: Received: from smtp.codeaurora.org ([198.145.11.231]:37626 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751452AbaLRCvM (ORCPT ); Wed, 17 Dec 2014 21:51:12 -0500 Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Steven Rostedt , Ingo Molnar Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Lime Yang , Stephen Boyd , Vikram Mulukutla Commit 6edb2a8a385f0cdef51dae37ff23e74d76d8a6ce introduced an array map_pages that contains the addresses returned by kmap_atomic. However, when unmapping those pages, map_pages[0] is unmapped before map_pages[1], breaking the nesting requirement as specified in the documentation for kmap_atomic/kunmap_atomic. This was caught by the highmem debug code present in kunmap_atomic. Fix the loop to do the unmapping properly. Reviewed-by: Stephen Boyd Reported-by: Lime Yang Signed-off-by: Vikram Mulukutla --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ab76b7b..bceed34 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4931,7 +4931,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, *fpos += written; out_unlock: - for (i = 0; i < nr_pages; i++){ + for (i = nr_pages - 1; i >= 0; i--) { kunmap_atomic(map_page[i]); put_page(pages[i]); } -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project