Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "This set of updates contains:

   - Another bugfix for the pathologic vm86 machinery.  Clear
     thread.vm86 on fork to prevent corrupting the parent state.  This
     comes along with an update to the vm86 selftest case

   - Fix another corner case in the ioapic setup code which causes a
     boot crash on some oddball systems

   - Fix the fallout from the dma allocation consolidation work, which
     leads to a NULL pointer dereference when the allocation code is
     called with a NULL device"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vm86: Set thread.vm86 to NULL on fork/clone
  selftests/x86: Add a fork() to entry_from_vm86 to catch fork bugs
  x86/ioapic: Prevent NULL pointer dereference in setup_ioapic_dest()
  x86/dma-mapping: Fix arch_dma_alloc_attrs() oops with NULL dev

4 files changed, 13 insertions, 3 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index bb6bfc01cb82..4f2821527014 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2547,7 +2547,9 @@ void __init setup_ioapic_dest(void)
                         mask = apic->target_cpus();
 
                 chip = irq_data_get_irq_chip(idata);
-                chip->irq_set_affinity(idata, mask, false);
+                /* Might be lapic_chip for irq 0 */
+                if (chip->irq_set_affinity)
+                        chip->irq_set_affinity(idata, mask, false);
         }
 }
 #endif
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 1b55de1267cf..cd99433b8ba1 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -131,11 +131,12 @@ void dma_generic_free_coherent(struct device *dev, size_t size, void *vaddr,
 
 bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp)
 {
+        if (!*dev)
+                *dev = &x86_dma_fallback_dev;
+
         *gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
         *gfp = dma_alloc_coherent_gfp_flags(*dev, *gfp);
 
-        if (!*dev)
-                *dev = &x86_dma_fallback_dev;
         if (!is_device_dma_capable(*dev))
                 return false;
         return true;
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index e28db181e4fc..9f7c21c22477 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -84,6 +84,9 @@ EXPORT_SYMBOL_GPL(idle_notifier_unregister);
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
         memcpy(dst, src, arch_task_struct_size);
+#ifdef CONFIG_VM86
+        dst->thread.vm86 = NULL;
+#endif
 
         return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
 }
diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c
index 421c607a8856..d075ea0e5ca1 100644
--- a/tools/testing/selftests/x86/entry_from_vm86.c
+++ b/tools/testing/selftests/x86/entry_from_vm86.c
@@ -230,5 +230,9 @@ int main(void)
         }
         clearhandler(SIGSEGV);
 
+        /* Make sure nothing explodes if we fork. */
+        if (fork() > 0)
+                return 0;
+
         return (nerrs == 0 ? 0 : 1);
 }