From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-22.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE091C47082 for ; Tue, 8 Jun 2021 15:53:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97A1461351 for ; Tue, 8 Jun 2021 15:53:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231416AbhFHPzh (ORCPT ); Tue, 8 Jun 2021 11:55:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:33720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230425AbhFHPzg (ORCPT ); Tue, 8 Jun 2021 11:55:36 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AF1B360FEA; Tue, 8 Jun 2021 15:53:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623167623; bh=Y0s5y8UvUQGn8A1rWcis5dg8fyss+/kqJGCt41rubgc=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=CQbphQVsb7ZAoau4YKL8co69sN785zak6gqpK21Z6chsxG2PKYJJwXQci/icel3f0 q/KQpQ+N7AF06t+P/cVQX9+1ZrxfyRf6HtzvbH75kgS4foDHqxKb+x7zawHMyJUlWH d2GXUc/0b9lu4vy9s0f4OIpQez7Cgy6iJvGpAKJq+lNAwMiekzHvA4jf4bg25MCLy7 i8ds5JQJjGEABxVd/sl8fYXeFdnWaNj1sx8uk6Zodag/cqP9ZEfIiwDYtm5/zHcJQR 0/gbtvG2Bi/aBVA2kkivd827cUAIiVcx4KBRodMJLvw2/UyQWkxXME9J2Zl6igFgjd eB9C1dliVwwiA== Subject: Re: [kbuild-all] Re: kernel/rcu/tree.c:2073:23: warning: stack frame size of 2704 bytes in function 'rcu_gp_kthread' To: paulmck@kernel.org, Rong Chen Cc: kernel test robot , kbuild-all@lists.01.org, clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org References: <202106061253.0X2QKyyI-lkp@intel.com> <20210606044926.GJ4397@paulmck-ThinkPad-P17-Gen-1> <4696fe3d-a7ad-acae-686e-6295ca327737@intel.com> <20210607151939.GP4397@paulmck-ThinkPad-P17-Gen-1> <20210608050134.GZ4397@paulmck-ThinkPad-P17-Gen-1> From: Nathan Chancellor Message-ID: Date: Tue, 8 Jun 2021 08:53:17 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210608050134.GZ4397@paulmck-ThinkPad-P17-Gen-1> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/7/2021 10:01 PM, Paul E. McKenney wrote: > On Tue, Jun 08, 2021 at 11:14:40AM +0800, Rong Chen wrote: >> >> >> On 6/7/21 11:19 PM, Paul E. McKenney wrote: >>> On Mon, Jun 07, 2021 at 05:18:21PM +0800, Rong Chen wrote: >>>> >>>> On 6/6/21 12:49 PM, Paul E. McKenney wrote: >>>>> On Sun, Jun 06, 2021 at 12:19:57PM +0800, kernel test robot wrote: >>>>>> Hi Paul, >>>>>> >>>>>> FYI, the error/warning still remains. >>>>>> >>>>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >>>>>> head: f5b6eb1e018203913dfefcf6fa988649ad11ad6e >>>>>> commit: 7dffe01765d9309b8bd5505503933ec0ec53d192 rcu: Add lockdep_assert_irqs_disabled() to raw_spin_unlock_rcu_node() macros >>>>>> date: 5 months ago >>>>>> config: powerpc-randconfig-r023-20210606 (attached as .config) >>>>>> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 551a697c5cf33275b66add4fc467fcf59084cffb) >>>>>> reproduce (this is a W=1 build): >>>>>> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross >>>>>> chmod +x ~/bin/make.cross >>>>>> # install powerpc cross compiling tool for clang build >>>>>> # apt-get install binutils-powerpc-linux-gnu >>>>>> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7dffe01765d9309b8bd5505503933ec0ec53d192 >>>>>> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >>>>>> git fetch --no-tags linus master >>>>>> git checkout 7dffe01765d9309b8bd5505503933ec0ec53d192 >>>>>> # save the attached .config to linux build tree >>>>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc >>>>>> >>>>>> If you fix the issue, kindly add following tag as appropriate >>>>>> Reported-by: kernel test robot >>>>>> >>>>>> All warnings (new ones prefixed by >>): >>>>>> >>>>>> In file included from kernel/rcu/tree.c:21: >>>>>> In file included from include/linux/kernel.h:12: >>>>>> In file included from include/linux/bitops.h:29: >>>>>> In file included from arch/powerpc/include/asm/bitops.h:62: >>>>>> arch/powerpc/include/asm/barrier.h:49:9: warning: '__lwsync' macro redefined [-Wmacro-redefined] >>>>>> #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") >>>>>> ^ >>>>>> :310:9: note: previous definition is here >>>>>> #define __lwsync __builtin_ppc_lwsync >>>>>> ^ >>>>>>>> kernel/rcu/tree.c:2073:23: warning: stack frame size of 2704 bytes in function 'rcu_gp_kthread' [-Wframe-larger-than=] >>>>>> static int __noreturn rcu_gp_kthread(void *unused) >>>>> Does -rcu commit 2f20de99a63b ("rcu: Make rcu_gp_cleanup() be noinline >>>>> for tracing") help? >>>> Hi Paul, >>>> >>>> The stack frame size decreased to 2256 bytes: >>>> >>>>   kernel/rcu/tree.c:2129:23: warning: stack frame size of 2256 bytes in >>>> function 'rcu_gp_kthread' [-Wframe-larger-than=] >>> Very good, thank you! Does the following patch (in addition to that >>> commit) also help? >> >> Hi Paul, >> >> I applied the below patch on commit 2f20de99a63b and the warning is gone. > > Very good, and thank you for your testing. I have applied the requested > Reported-by and your Tested-by on the commit shown below. Please let > me know if you would prefer some other Reported/Tested setup. > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 336e92638287615d47c07af4ff6feb397cfe2084 > Author: Paul E. McKenney > Date: Mon Jun 7 21:57:02 2021 -0700 > > rcu: Make rcu_gp_init() and rcu_gp_fqs_loop noinline to conserve stack > > The kbuild test project found an oversized stack frame in rcu_gp_kthread() > for some kernel configurations. This oversizing was due to a very large > amount of inlining, which is unnecessary due to the fact that this code > executes infrequently. This commit therefore marks rcu_gp_init() and > rcu_gp_fqs_loop noinline to conserve stack space. > > Reported-by: kernel test robot > Tested-by: Rong Chen > Signed-off-by: Paul E. McKenney > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 13bd8eee62bf..ef435aeac993 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1737,7 +1737,7 @@ static void rcu_strict_gp_boundary(void *unused) > /* > * Initialize a new grace period. Return false if no grace period required. > */ > -static bool rcu_gp_init(void) > +static noinline bool rcu_gp_init(void) Small comment if it is not too late. noinline_for_stack expands to the same thing but is self documenting :) that way people do not have to git blame to see why these are marked as noinline (not that too many people are probably touching this but still). > { > unsigned long firstseq; > unsigned long flags; > @@ -1931,7 +1931,7 @@ static void rcu_gp_fqs(bool first_time) > /* > * Loop doing repeated quiescent-state forcing until the grace period ends. > */ > -static void rcu_gp_fqs_loop(void) > +static noinline void rcu_gp_fqs_loop(void) > { > bool first_gp_fqs; > int gf = 0; > Cheers, Nathan