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=-21.2 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,SPF_HELO_NONE,SPF_PASS 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 D5BB4C48BCF for ; Wed, 9 Jun 2021 17:23:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B572661040 for ; Wed, 9 Jun 2021 17:23:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231512AbhFIRZF (ORCPT ); Wed, 9 Jun 2021 13:25:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:57734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231356AbhFIRZE (ORCPT ); Wed, 9 Jun 2021 13:25:04 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D026A61376; Wed, 9 Jun 2021 17:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623259389; bh=Vb6McRiT2/CHdsESXthRynLQK21J9OQeIFmCE6RS/G4=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ZaiiBDy7oq+hibjvGfxp/Qu/VwZ17V1vmC29alYpv3he42i+ut3t9N+LHvgMVpaha fMnY6gLduoYXkx6gW/sP8/aZC6U2v2L4TiHkWK/+/iXVuoeiccs/M2to21LYCtJh60 xVJonVyUcqWuW1Ssyw5z0dYsxOjHsyK/2u8PUtgYErhAAUlOZ3fjvEgwfRZlWucym3 UWWc0nLDuFP5tLO9bESY0brdiC26TWMUHV/s6rmphsYvwHX++D9iclkQE1pKFWk6WY tixFboUOO6tNgTFOr9LXApH4+/r2nCRLCFox9AY6mmabefLija4ZuzNdW8VnPv3z2v RYbjaWWZrkyig== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B35445C039E; Wed, 9 Jun 2021 10:23:09 -0700 (PDT) Date: Wed, 9 Jun 2021 10:23:09 -0700 From: "Paul E. McKenney" To: Nathan Chancellor Cc: Rong Chen , kernel test robot , kbuild-all@lists.01.org, clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [kbuild-all] Re: kernel/rcu/tree.c:2073:23: warning: stack frame size of 2704 bytes in function 'rcu_gp_kthread' Message-ID: <20210609172309.GG4397@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@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> <20210609035805.GA4397@paulmck-ThinkPad-P17-Gen-1> <7f03e5bc-d8a3-74a4-273a-f8047b62ab02@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7f03e5bc-d8a3-74a4-273a-f8047b62ab02@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 08, 2021 at 09:14:29PM -0700, Nathan Chancellor wrote: > On 6/8/2021 8:58 PM, Paul E. McKenney wrote: > > On Tue, Jun 08, 2021 at 08:53:17AM -0700, Nathan Chancellor wrote: > > > 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). > > > > How about like the following? > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 8aa0ceef4264012abd7b98d29f0a968f0f0046cb > > 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_for_stack to conserve stack space. > > Reported-by: kernel test robot > > Tested-by: Rong Chen > > [ paulmck: noinline_for_stack per Nathan Chancellor. ] > > Signed-off-by: Paul E. McKenney > > Reviewed-by: Nathan Chancellor Applied, thank you! Thanx, Paul > Thanks! > > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 13bd8eee62bf..d8052adcdcb1 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_for_stack bool rcu_gp_init(void) > > { > > 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_for_stack void rcu_gp_fqs_loop(void) > > { > > bool first_gp_fqs; > > int gf = 0; > >