Re: [PATCH v7 2/4] lib/test_bitmap.c: Add for_each_set_clump test cases

[Rong Chen]

On 6/7/20 7:15 AM, Syed Nayyar Waris wrote:
> On Fri, Jun 5, 2020 at 5:54 PM Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > On Fri, Jun 05, 2020 at 02:12:54AM +0530, Syed Nayyar Waris wrote:
> > > On Sun, May 31, 2020 at 12:50 AM kbuild test robot <lkp@xxxxxxxxx> wrote:
> > > > > > WARNING: modpost: lib/test_bitmap.o(.data+0xe80): Section mismatch in reference from the variable clump_test_data to the variable .init.rodata:clump_exp1
> > > > The variable clump_test_data references
> > > > the variable __initconst clump_exp1
> > > > If the reference is valid then annotate the
> > > > variable with or __refdata (see linux/init.h) or name the variable:
> > > >
> > > > --
> > > > > > WARNING: modpost: lib/test_bitmap.o(.data+0xec8): Section mismatch in reference from the variable clump_test_data to the variable .init.rodata:clump_exp2
> > > > The variable clump_test_data references
> > > > the variable __initconst clump_exp2
> > > > If the reference is valid then annotate the
> > > > variable with or __refdata (see linux/init.h) or name the variable:
> > > >
> > > > --
> > > > > > WARNING: modpost: lib/test_bitmap.o(.data+0xf10): Section mismatch in reference from the variable clump_test_data to the variable .init.rodata:clump_exp3
> > > > The variable clump_test_data references
> > > > the variable __initconst clump_exp3
> > > > If the reference is valid then annotate the
> > > > variable with or __refdata (see linux/init.h) or name the variable:
> > > >
> > > > --
> > > > > > WARNING: modpost: lib/test_bitmap.o(.data+0xf58): Section mismatch in reference from the variable clump_test_data to the variable .init.rodata:clump_exp4
> > > > The variable clump_test_data references
> > > > the variable __initconst clump_exp4
> > > > If the reference is valid then annotate the
> > > > variable with or __refdata (see linux/init.h) or name the variable:
> > > I am unable to reproduce the compilation warning.
> > You have to enable section mismatch checker.
> >
> > > I ran the command:
> > > make W=1 C=1 ARCH=x86_64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'  lib/
> > >
> > > But the compilation warning didn't show up. Can anyone please point to me
> > > what I am doing wrong here? How shall I reproduce the warning? Thanks !
> > You put some data into init section of the object, while you are trying to
> > access it from non-init one. It's easy-to-fix issue.
> >
> > --
> > With Best Regards,
> > Andy Shevchenko
> Thanks! I have made code changes for the above warning. Actually I am
> still unable to reproduce the compilation warning. But I believe the
> following code fix will fix the compilation warning:
>
> In file lib/test_bitmap.c
>
> @@ -692,7 +692,7 @@ struct clump_test_data_params {
>          unsigned long const *exp;
>   };
>
> -struct clump_test_data_params clump_test_data[] =
> +static struct clump_test_data_params clump_test_data[] __initdata =
>                                          { {{0}, 2, 0, 64, 8, clump_exp1},
>                                          {{0}, 8, 2, 240, 24, clump_exp2},
>                                          {{0}, 8, 10, 240, 30, clump_exp3},
>
>
>
> Let me know if I should submit a new patchset (v8) for
> 'for_each_set_clump' including above code fix.
>
> Just to share how I attempted to reproduce the warning (but unsuccessful):
>
> Step 1: Use the config file in attachment. Download, extract, rename
> file to .config at the root of the tree.
> Step 2: '$ make lib/'
> No warning reproduced after above step 2.
> Step 3: '$ make W=1 C=1 ARCH=x86_64 CF='-fdiagnostic-prefix
> -D__CHECK_ENDIAN__' lib/'
> After step 3 I got error in build:
> scripts/kconfig/conf  --syncconfig Kconfig
>    CHECK   scripts/mod/empty.c
> No such file: asan-globals=1
> scripts/Makefile.build:266: recipe for target 'scripts/mod/empty.o' failed
> make[1]: *** [scripts/mod/empty.o] Error 1
> Makefile:1147: recipe for target 'prepare0' failed
> make: *** [prepare0] Error 2
>
> The command in above step 3 was mentioned in the bot mail.
>
> Regards
> Syed Nayyar Waris

Hi Syed Nayyar Waris,

We can reproduce the warning with the steps in original report,
you may need to build the whole kernel instead of the 'lib'.

Best Regards,
Rong Chen