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    SubjectRe: [2.6.37-rc1] /proc/vmstat failure.
    On Thu, Nov 04, 2010 at 10:52:51AM +0800, Américo Wang wrote:
    > On Thu, Nov 04, 2010 at 10:20:52AM +0800, Wu Fengguang wrote:
    > >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.
    > >
    >
    > Yup! I think it is good to have this.
    >
    > >/cc/linux-next/scripts/mod/file2alias.c:88: warning: pointer of type ‘void *’ used in arithmetic
    > ...
    > >/cc/linux-next/scripts/mod/modpost.c:1565: warning: pointer of type ‘void *’ used in arithmetic
    > >
    >
    > No problem, this is from kbuild and most of them that I checked are actually fine,
    > we can send patches to remove these warnings.

    Confirmed. Now my full kernel build is complete and the above are the
    only warnings I see. So it should be easy to add the -Wpointer-arith
    check.

    Thanks,
    Fengguang
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