From 4e8455d5812358e7c21cdac9c9cb24dc88b8b398 Mon Sep 17 00:00:00 2001 From: Daniel J Blueman Date: Mon, 1 Oct 2012 14:42:05 +0800 Subject: [PATCH] x86, amd, mce: Avoid NULL pointer reference on CPU northbridge lookup When booting on a federated multi-server system (NumaScale), the processor Northbridge lookup returns NULL; add guards to prevent this causing an oops. On those systems, the northbridge is accessed through MMIO and the "normal" northbridge enumeration in amd_nb.c doesn't work since we're generating the northbridge ID from the initial APIC ID and the last is not unique on those systems. Long story short, we end up without northbridge descriptors. Signed-off-by: Daniel J Blueman Cc: stable@vger.kernel.org # 3.6 Link: http://lkml.kernel.org/r/1349073725-14093-1-git-send-email-daniel@numascale-asia.com [ Boris: beef up commit message ] Signed-off-by: Borislav Petkov Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/mcheck/mce_amd.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c index c4e916d773780..698b6ec12e0f4 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c @@ -576,12 +576,10 @@ static __cpuinit int threshold_create_bank(unsigned int cpu, unsigned int bank) int err = 0; if (shared_bank[bank]) { - nb = node_to_amd_nb(amd_get_nb_id(cpu)); - WARN_ON(!nb); /* threshold descriptor already initialized on this node? */ - if (nb->bank4) { + if (nb && nb->bank4) { /* yes, use it */ b = nb->bank4; err = kobject_add(b->kobj, &dev->kobj, name); @@ -615,8 +613,10 @@ static __cpuinit int threshold_create_bank(unsigned int cpu, unsigned int bank) atomic_set(&b->cpus, 1); /* nb is already initialized, see above */ - WARN_ON(nb->bank4); - nb->bank4 = b; + if (nb) { + WARN_ON(nb->bank4); + nb->bank4 = b; + } } err = allocate_threshold_blocks(cpu, bank, 0, -- 2.39.5