Re: [2.6.37-rc1] /proc/vmstat failure.

[Wu Fengguang <fengguang.wu@intel.com>]

On Thu, Nov 04, 2010 at 05:54:48AM +0800, Tetsuo Handa wrote:
> Wu Fengguang wrote:
> > On Wed, Nov 03, 2010 at 07:11:11PM +0800, Tetsuo Handa wrote:
> > > Hello.
> > > 
> > > "cat /proc/vmstat" triggered below failure.
> > > 
> > > BUG: unable to handle kernel paging request at 07c06d16
> > > IP: [<c050c336>] strnlen+0x6/0x20
> > 
> > It seems that m->private is of type (void *) while the original v is
> > (unsigned long *). Can be fixed by the following patch.
> 
> Fixed by this patch. Thank you.

Great, thanks!

> By the way, GCC treats "(void *) + offset" as "(char *) + offset"
> but it is GCC specific extention. Maybe we should avoid such usage
> in order to avoid build failure for other compilers.

"(void *) + offset" seems to be used quite often.

I tried enable this gcc option, only to see huge amount of warnings.

       -Wpointer-arith
           Warn about anything that depends on the "size of" a
           function type or of "void".  GNU C assigns these types a
           size of 1, for convenience in calculations with "void *"
           pointers and pointers to functions.

/cc/linux-next/scripts/mod/file2alias.c: In function ‘device_id_check’:
/cc/linux-next/scripts/mod/file2alias.c:88: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:88: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:88: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:94: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:94: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:94: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c: In function ‘do_usb_table’:
/cc/linux-next/scripts/mod/file2alias.c:275: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c: In function ‘do_table’:
/cc/linux-next/scripts/mod/file2alias.c:870: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c: In function ‘handle_moddevtable’:
/cc/linux-next/scripts/mod/file2alias.c:897: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/file2alias.c:897: warning: pointer of type ‘void *’ used in arithmetic
  HOSTCC  scripts/mod/modpost.o
/cc/linux-next/scripts/mod/modpost.c: In function ‘parse_elf’:
/cc/linux-next/scripts/mod/modpost.c:412: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:456: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:472: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:489: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:491: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:491: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:494: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:501: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:503: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:503: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c: In function ‘sec_name’:
/cc/linux-next/scripts/mod/modpost.c:716: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:717: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c: In function ‘sech_name’:
/cc/linux-next/scripts/mod/modpost.c:723: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:724: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c: In function ‘reloc_location’:
/cc/linux-next/scripts/mod/modpost.c:1443: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:1444: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:1444: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c: In function ‘section_rela’:
/cc/linux-next/scripts/mod/modpost.c:1520: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:1521: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c: In function ‘section_rel’:
/cc/linux-next/scripts/mod/modpost.c:1564: warning: pointer of type ‘void *’ used in arithmetic
/cc/linux-next/scripts/mod/modpost.c:1565: warning: pointer of type ‘void *’ used in arithmetic

Thanks,
Fengguang