Messages in this thread | | | Subject | Re: [kbuild-all] Re: kernel/rcu/tree.c:2073:23: warning: stack frame size of 2704 bytes in function 'rcu_gp_kthread' | From | Nathan Chancellor <> | Date | Tue, 8 Jun 2021 21:14:29 -0700 |
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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 <lkp@intel.com> >>>>>>>> >>>>>>>> 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") >>>>>>>> ^ >>>>>>>> <built-in>: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 <paulmck@kernel.org> >>> 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 <lkp@intel.com> >>> Tested-by: Rong Chen <rong.a.chen@intel.com> >>> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> >>> >>> 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 <paulmck@kernel.org> > 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 <lkp@intel.com> > Tested-by: Rong Chen <rong.a.chen@intel.com> > [ paulmck: noinline_for_stack per Nathan Chancellor. ] > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
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; >
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