Re: [PATCH] acpi: Fix potential call to a freed memory section.

["Aaron Durbin" <adurbin@google.com>]

On 5/16/07, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed, 16 May 2007 09:09:11 -0700 Aaron Durbin <adurbin@google.com> wrote:
>
> > Strip __cpuinit[data] from Node <-> PXM routines and supporting data structures.
> > Also make pxm_to_node_map and node_to_pxm_map local to the numa acpi module.
> >
> > This fixes a bug triggered by the following conditions:
> > - boot on a machine with a SLIT table defined
> > - kernel is configured w/ CONFIG_HOTPLUG_CPU=n
> > - cat /sys/devices/system/node/node*/distance
> > This will cause an oops by calling into a freed memory section.
> >
> > In particular, on x86_64, __node_distance calls node_to_pxm().
> >
>
> Yeah, those section warnings we get aren't just noise.
>
> I think this patch is also needed in 2.6.21.x, yes?

Yes, this bug exists in 2.6.21 as well.

>
> > ---
> >
> > diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> > index 8fcd6a1..a2efae8 100644
> > --- a/drivers/acpi/numa.c
> > +++ b/drivers/acpi/numa.c
> > @@ -40,19 +40,19 @@ #define PXM_INVAL -1
> >  #define NID_INVAL    -1
> >
> >  /* maps to convert between proximity domain and logical node ID */
> > -int __cpuinitdata pxm_to_node_map[MAX_PXM_DOMAINS]
> > +static int pxm_to_node_map[MAX_PXM_DOMAINS]
> >                               = { [0 ... MAX_PXM_DOMAINS - 1] = NID_INVAL };
> > -int __cpuinitdata node_to_pxm_map[MAX_NUMNODES]
> > +static int node_to_pxm_map[MAX_NUMNODES]
> >                               = { [0 ... MAX_NUMNODES - 1] = PXM_INVAL };
> >
> > -int __cpuinit pxm_to_node(int pxm)
> > +int pxm_to_node(int pxm)
> >  {
> >       if (pxm < 0)
> >               return NID_INVAL;
> >       return pxm_to_node_map[pxm];
> >  }
> >
> > -int __cpuinit node_to_pxm(int node)
> > +int node_to_pxm(int node)
> >  {
> >       if (node < 0)
> >               return PXM_INVAL;
> > diff --git a/include/acpi/acpi_numa.h b/include/acpi/acpi_numa.h
> > index f9d2bde..b62cd36 100644
> > --- a/include/acpi/acpi_numa.h
> > +++ b/include/acpi/acpi_numa.h
> > @@ -11,11 +11,8 @@ #else
> >  #define MAX_PXM_DOMAINS (256)        /* Old pxm spec is defined 8 bit */
> >  #endif
> >
> > -extern int __cpuinitdata pxm_to_node_map[MAX_PXM_DOMAINS];
> > -extern int __cpuinitdata node_to_pxm_map[MAX_NUMNODES];
> > -
> > -extern int __cpuinit pxm_to_node(int);
> > -extern int __cpuinit node_to_pxm(int);
> > +extern int pxm_to_node(int);
> > +extern int node_to_pxm(int);
> >  extern int __cpuinit acpi_map_pxm_to_node(int);
> >  extern void __cpuinit acpi_unmap_pxm_to_node(int);
> >
>
> Moving from __fooinit into .text is always safe.  Len, do you want me to
> merge this up?
>
>