Re: [kbuild-all] Re: drivers/video/backlight/ltv350qv.c:192:12: warning: stack frame size of 13472 bytes in function 'ltv350qv_power'

[Chen, Rong A]

On 10/29/2020 11:28 PM, Andrey Konovalov wrote:
> On Sun, Oct 25, 2020 at 8:17 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > On Mon, 26 Oct 2020 02:15:37 +0800 kernel test robot <lkp@xxxxxxxxx> wrote:
> >
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > > head:   d76913908102044f14381df865bb74df17a538cb
> > > commit: cae9dc35ed9ff82a99754e51d57ff6c332e1f7e4 kasan: allow enabling stack tagging for tag-based mode
> > > date:   3 months ago
> > > config: arm64-randconfig-r005-20201026 (attached as .config)
> > > compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 1c8371692dfe8245bc6690ff1262dcced4649d21)
> > > 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 arm64 cross compiling tool for clang build
> > >          # apt-get install binutils-aarch64-linux-gnu
> > >          # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cae9dc35ed9ff82a99754e51d57ff6c332e1f7e4
> > >          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > >          git fetch --no-tags linus master
> > >          git checkout cae9dc35ed9ff82a99754e51d57ff6c332e1f7e4
> > >          # save the attached .config to linux build tree
> > >          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > > > > drivers/video/backlight/ltv350qv.c:192:12: warning: stack frame size of 13472 bytes in function 'ltv350qv_power' [-Wframe-larger-than=]
> >
> > That's a lot of stack.
> >
> > >     static int ltv350qv_power(struct ltv350qv *lcd, int power)
> > >                ^
> > >     1 warning generated.
> > >
> > > vim +/ltv350qv_power +192 drivers/video/backlight/ltv350qv.c
> >
> > Odd - the code looks pretty normal.  It is possible that your compiler
> > is (crazily) inlining ltv350qv_write_reg()?
>
> This is the same issue in LLVM that was reported by Arnd for generic
> KASAN (also see KASAN_STACK_ENABLE option description). By default
> KASAN shouldn't have stack instrumentation enabled unless
> KASAN_STACK_ENABLE is specified. Perhaps it makes sense to disable it
> for KASAN_SW_TAGS config on the kernel test robot.

Hi Andrey,

Thanks for your advice, we'll take a look.

Best Regards,
Rong Chen

> [1] https://bugs.llvm.org/show_bug.cgi?id=38809
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