From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754024Ab0KDDnx (ORCPT ); Wed, 3 Nov 2010 23:43:53 -0400 Received: from mga02.intel.com ([134.134.136.20]:55033 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753477Ab0KDDnw (ORCPT ); Wed, 3 Nov 2010 23:43:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.58,293,1286175600"; d="scan'208";a="570197122" Date: Thu, 4 Nov 2010 11:43:49 +0800 From: Wu Fengguang To: =?utf-8?Q?Am=C3=A9rico?= Wang Cc: Tetsuo Handa , "mrubin@google.com" , "david@fromorbit.com" , "axboe@kernel.dk" , "kosaki.motohiro@jp.fujitsu.com" , "nickpiggin@yahoo.com.au" , "akpm@linux-foundation.org" , "torvalds@linux-foundation.org" , "linux-kernel@vger.kernel.org" Subject: Re: [2.6.37-rc1] /proc/vmstat failure. Message-ID: <20101104034349.GA20775@localhost> References: <201011010053.ADE86905.JMLFHVtSQOOFOF@I-love.SAKURA.ne.jp> <201011032011.BAB21899.OHVQtFLSFJMFOO@I-love.SAKURA.ne.jp> <20101103174643.GA4985@localhost> <201011040654.GDB05271.SOFJFFtOMLHOQV@I-love.SAKURA.ne.jp> <20101104022052.GA7800@localhost> <20101104025251.GA5210@cr0.nay.redhat.com> <20101104025341.GA18429@localhost> <20101104033148.GB5210@cr0.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20101104033148.GB5210@cr0.nay.redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 04, 2010 at 11:31:48AM +0800, Américo Wang wrote: > On Thu, Nov 04, 2010 at 10:53:41AM +0800, Wu Fengguang wrote: > >On Thu, Nov 04, 2010 at 10:52:51AM +0800, Américo Wang wrote: > >> On Thu, Nov 04, 2010 at 10:20:52AM +0800, Wu Fengguang wrote: > >> >On Thu, Nov 04, 2010 at 05:54:48AM +0800, Tetsuo Handa wrote: > >> >> Wu Fengguang wrote: > >> >> > On Wed, Nov 03, 2010 at 07:11:11PM +0800, Tetsuo Handa wrote: > >> >> > > Hello. > >> >> > > > >> >> > > "cat /proc/vmstat" triggered below failure. > >> >> > > > >> >> > > BUG: unable to handle kernel paging request at 07c06d16 > >> >> > > IP: [] strnlen+0x6/0x20 > >> >> > > >> >> > It seems that m->private is of type (void *) while the original v is > >> >> > (unsigned long *). Can be fixed by the following patch. > >> >> > >> >> Fixed by this patch. Thank you. > >> > > >> >Great, thanks! > >> > > >> >> By the way, GCC treats "(void *) + offset" as "(char *) + offset" > >> >> but it is GCC specific extention. Maybe we should avoid such usage > >> >> in order to avoid build failure for other compilers. > >> > > >> >"(void *) + offset" seems to be used quite often. > >> > > >> >I tried enable this gcc option, only to see huge amount of warnings. > >> > > >> > -Wpointer-arith > >> > Warn about anything that depends on the "size of" a > >> > function type or of "void". GNU C assigns these types a > >> > size of 1, for convenience in calculations with "void *" > >> > pointers and pointers to functions. > >> > > >> > >> Yup! I think it is good to have this. > >> > >> >/cc/linux-next/scripts/mod/file2alias.c:88: warning: pointer of type ‘void *’ used in arithmetic > >> ... > >> >/cc/linux-next/scripts/mod/modpost.c:1565: warning: pointer of type ‘void *’ used in arithmetic > >> > > >> > >> No problem, this is from kbuild and most of them that I checked are actually fine, > >> we can send patches to remove these warnings. > > > >Confirmed. Now my full kernel build is complete and the above are the > >only warnings I see. So it should be easy to add the -Wpointer-arith > >check. > > > > Well, after I tried to compile with it, I got lots of warnings. > Most of them that I checked is something like: > > (void *) CONST_PTR + OFFSET > > in macros. In order to fix this, we need to: > > (void *) ((char *) CONST_PTR + OFFSET) > > So, we have to make some efforts to kill all the warnings. :-/ Sorry I didn't run allyesconfig/allmodconfig as suggested by Tetsuo. So expect more warnings.. Thanks, Fengguang