RE: [PATCH] sysinfo: include availram field in sysinfo struct

[David Laight <David.Laight@ACULAB.COM>]

> > These are the header changes for quick look:
> > {{{
> > diff --git a/include/uapi/linux/sysinfo.h b/include/uapi/linux/sysinfo.h
> > index 6e77e90..fe84c6a 100644
> > --- a/include/uapi/linux/sysinfo.h
> > +++ b/include/uapi/linux/sysinfo.h
> > @@ -12,7 +12,6 @@ struct sysinfo {
> >         __kernel_ulong_t freeram;       /* Available memory size */
> >         __kernel_ulong_t sharedram;     /* Amount of shared memory */
> >         __kernel_ulong_t bufferram;     /* Memory used by buffers */
> > -       __kernel_ulong_t availram;      /* Memory available for allocation */
> >         __kernel_ulong_t totalswap;     /* Total swap space size */
> >         __kernel_ulong_t freeswap;      /* swap space still available */
> >         __u16 procs;                    /* Number of current processes */
> > @@ -20,7 +19,8 @@ struct sysinfo {
> >         __kernel_ulong_t totalhigh;     /* Total high memory size */
> >         __kernel_ulong_t freehigh;      /* Available high memory size */
> >         __u32 mem_unit;                 /* Memory unit size in bytes */
> > -       char _f[20-2*sizeof(__kernel_ulong_t)-sizeof(__u32)];   /*
> > Padding: libc5 uses this.. */
> > +       __kernel_ulong_t availram;      /* Memory available for allocation */
> > +       char _f[20-3*sizeof(__kernel_ulong_t)-sizeof(__u32)];   /*
> > Padding: libc5 uses this.. */
> >  };
> > }}}
> >
> > If this is fine, I will push the new patch set.
> 
> Please CC linux-api@vger.kernel.org on the new posting.

That is probably still broken.
If __kernel_ulong_t is 64bit there is architecture
dependant padding after mem_unit.

In particular a 32bit x86 app running on a 64bit kernel
will probably see the wrong layout.

You definitely need a compile-time assert on the total structure size.

	David

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