From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752210Ab0CSX1g (ORCPT ); Fri, 19 Mar 2010 19:27:36 -0400 Received: from hera.kernel.org ([140.211.167.34]:54470 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752138Ab0CSX1e (ORCPT ); Fri, 19 Mar 2010 19:27:34 -0400 Message-ID: <4BA407B8.7070503@kernel.org> Date: Fri, 19 Mar 2010 16:24:40 -0700 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100228 SUSE/3.0.3-1.1.1 Thunderbird/3.0.3 MIME-Version: 1.0 To: "H. Peter Anvin" CC: Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, Ian Campbell , Peter Zijlstra , Linus Torvalds Subject: Re: [PATCH -v3] x86: do not free zero sized per cpu areas References: <4B914A61.20409@kernel.org> <4BA3F82D.5090807@kernel.org> <4BA3F8ED.2090600@zytor.com> In-Reply-To: <4BA3F8ED.2090600@zytor.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19/2010 03:21 PM, H. Peter Anvin wrote: > On 03/19/2010 03:18 PM, Yinghai Lu wrote: >> From: Ian Campbell >> >> This avoids an infinite loop in free_early_partial(). >> >> Add a warning to free_early_partial to catch future problems. >> >> -v3: according to hpa, don't bother caller. >> >> Signed-off-by: Ian Campbell >> Signed-off-by: Yinghai Lu >> Cc: Peter Zijlstra >> Cc: Ingo Molnar >> --- >> kernel/early_res.c | 5 +++++ >> 1 files changed, 5 insertions(+), 0 deletions(-) >> >> diff --git a/kernel/early_res.c b/kernel/early_res.c >> index 3cb2c66..f3a861b 100644 >> --- a/kernel/early_res.c >> +++ b/kernel/early_res.c >> @@ -333,6 +333,11 @@ void __init free_early_partial(u64 start, u64 end) >> struct early_res *r; >> int i; >> >> + if (WARN_ONCE(start >= end, >> + "free_early_partial got wrong start/end %#llx/%#llx\n", >> + start, end)) >> + return; >> + >> try_next: >> i = find_overlapped_early(start, end); >> if (i >= max_early_res) > > No, that's wrong. > > The workaround is still needed for the case of equality to avoid the > infinite loop. > > So you need an: > > if (start == end) > return; > confused, do you mean like this if (start < end), find_overlapped_early will stop the loop. From: Ian Campbell This avoids an infinite loop in free_early_partial(). Add a warning to free_early_partial to catch future problems. -v3: according to hpa, don't bother caller. Signed-off-by: Ian Campbell Signed-off-by: Yinghai Lu Cc: Peter Zijlstra Cc: Ingo Molnar --- kernel/early_res.c | 8 ++++++++ 1 file changed, 8 insertions(+) Index: linux-2.6/kernel/early_res.c =================================================================== --- linux-2.6.orig/kernel/early_res.c +++ linux-2.6/kernel/early_res.c @@ -333,6 +333,14 @@ void __init free_early_partial(u64 start struct early_res *r; int i; + if (start >= end) { + WARN_ONCE(1, + "free_early_partial got wrong start/end %#llx/%#llx\n", + start, end); + + return; + } + try_next: i = find_overlapped_early(start, end); if (i >= max_early_res)