Subject: Re: linux-next: build warning after merge of the akpm-current tree

From: Walter Wu <[email-masked]>
Date: Thu, 5 Mar 2020 16:54:36 +0800

On Thu, 2020-03-05 at 16:37 +1100, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the akpm-current tree, today's linux-next build (x86_64
> allmodconfig) produced this warning:
> 
> mm/kasan/common.o: warning: objtool: kasan_report()+0x17: call to report_enabled() with UACCESS enabled
> In file included from include/linux/bitmap.h:9,
>                  from include/linux/cpumask.h:12,
>                  from arch/x86/include/asm/paravirt.h:17,
>                  from arch/x86/include/asm/irqflags.h:72,
>                  from include/linux/irqflags.h:16,
>                  from include/linux/rcupdate.h:26,
>                  from include/linux/rculist.h:11,
>                  from include/linux/pid.h:5,
>                  from include/linux/sched.h:14,
>                  from include/linux/uaccess.h:6,
>                  from arch/x86/include/asm/fpu/xstate.h:5,
>                  from arch/x86/include/asm/pgtable.h:26,
>                  from include/linux/kasan.h:15,
>                  from lib/test_kasan.c:12:
> In function 'memmove',
>     inlined from 'kmalloc_memmove_invalid_size' at lib/test_kasan.c:301:2:
> include/linux/string.h:441:9: warning: '__builtin_memmove' specified bound 18446744073709551614 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
>   441 |  return __builtin_memmove(p, q, size);
>       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Introduced by commit
> 
>   519e500fac64 ("kasan: add test for invalid size in memmove")
> 
> That's a bit annoying during a normal x86_64 allmodconfig build ...
> 

Hi Stephen and Dmitry,

I'm sorry for the build warning, it doesn't generate in our local
environment(arm64/x86_64). Would you tell me what toolchains can
reproduce it?

Dmitry, Thanks for your suggestion.

Thanks

Walter