Re: [PATCH -tip] x86: uv - prevent NULL dereference in uv_system_init

Cyrill Gorcunov
2009-05-03T09:01:24Z

[Ingo Molnar - Sun, May 03, 2009 at 10:48:47AM +0200]
|
| * Jack Steiner <steiner@sgi.com> wrote:
|
| > > arch/x86/kernel/apic/x2apic_uv_x.c | 3 +++
| > > 1 file changed, 3 insertions(+)
| > >
| > > Index: linux-2.6.git/arch/x86/kernel/apic/x2apic_uv_x.c
| > > =====================================================================
| > > --- linux-2.6.git.orig/arch/x86/kernel/apic/x2apic_uv_x.c
| > > +++ linux-2.6.git/arch/x86/kernel/apic/x2apic_uv_x.c
| > > @@ -584,15 +584,18 @@ void __init uv_system_init(void)
| > >
| > > bytes = sizeof(struct uv_blade_info) * uv_num_possible_blades();
| > > uv_blade_info = kmalloc(bytes, GFP_KERNEL);
| > > + BUG_ON(!uv_blade_info);
| > >
| > > get_lowmem_redirect(&lowmem_redir_base, &lowmem_redir_size);
| > >
| > > bytes = sizeof(uv_node_to_blade[0]) * num_possible_nodes();
| > > uv_node_to_blade = kmalloc(bytes, GFP_KERNEL);
| > > + BUG_ON(!uv_node_to_blade);
| > > memset(uv_node_to_blade, 255, bytes);
| > >
| > > bytes = sizeof(uv_cpu_to_blade[0]) * num_possible_cpus();
| > > uv_cpu_to_blade = kmalloc(bytes, GFP_KERNEL);
| > > + BUG_ON(!uv_cpu_to_blade);
| > > memset(uv_cpu_to_blade, 255, bytes);
|
| Hm, would be nice if we had a __GFP_PANIC variant in kmalloc that
| would just panic straight in the allocator, when allocation failure
| is not acceptable. (Andrew Cc:-ed)
|
| It does not increase the priority of the allocation nor does it
| trigger any 'dont fail' logic - it is simply the central expression
| of 'this should not have failed, panic'.
|
| Thus we'd avoid all these duplicated BUG_ON() places.
|
| Ingo
|

Yes, we have SLAB_PANIC, the similar (in behaviour) could be
done for kmalloc. (Pekka and Rik CC'ed as well)

-- Cyrill