Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755413AbZJ1Rzd (ORCPT ); Wed, 28 Oct 2009 13:55:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755340AbZJ1Rzc (ORCPT ); Wed, 28 Oct 2009 13:55:32 -0400 Received: from nfitmail.nfit.au.dk ([130.225.31.129]:11543 "EHLO smtp.nfit.au.dk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755323AbZJ1Rzc convert rfc822-to-8bit (ORCPT ); Wed, 28 Oct 2009 13:55:32 -0400 To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, a.p.zijlstra@chello.nl Subject: [PATCH 1/2] Fix race in debug_kmap_atomic() which could cause warn_count to underflow References: From: Soeren Sandmann Date: 28 Oct 2009 18:55:36 +0100 In-Reply-To: Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.4 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT X-NFIT-RelayAddr: 130.225.16.142 X-NFIT-Solido-Score: 0. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1108 Lines: 31 debug_kmap_atomic() tries to prevent ever printing more than 10 warnings, but it does so by testing whether an unsigned integer is equal to 0. However, if the warning is caused by a nested IRQ, then this counter may underflow and the stream of warnings will never end. Fix that by using a signed integer instead. Signed-off-by: Søren Sandmann Pedersen --- mm/highmem.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/highmem.c b/mm/highmem.c index 25878cc..33587de 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -426,9 +426,9 @@ void __init page_address_init(void) void debug_kmap_atomic(enum km_type type) { - static unsigned warn_count = 10; + static int warn_count = 10; - if (unlikely(warn_count == 0)) + if (unlikely(warn_count < 0)) return; if (unlikely(in_interrupt())) { -- 1.6.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/