[PATCH] x86: cpu_init(): avoid GFP_KERNEL allocation while atomic

The patch fixes two issues:

1.  cpu_init is called with interrupt disabled.  Allocating gdt table
   there isn't good at runtime.

2. gdt table page cause memory leak in CPU hotplug case.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 20 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 44f2c5f2dda..640364d9b66 100644
--- a/arch/i386/kernel/cpu/common.c
+++ b/arch/i386/kernel/cpu/common.c
@@ -613,6 +613,12 @@ void __cpuinit cpu_init(void)
                 set_in_cr4(X86_CR4_TSD);
         }
 
+        /* The CPU hotplug case */
+        if (cpu_gdt_descr->address) {
+                gdt = (struct desc_struct *)cpu_gdt_descr->address;
+                memset(gdt, 0, PAGE_SIZE);
+                goto old_gdt;
+        }
         /*
          * This is a horrible hack to allocate the GDT.  The problem
          * is that cpu_init() is called really early for the boot CPU
@@ -631,7 +637,7 @@ void __cpuinit cpu_init(void)
                                 local_irq_enable();
                 }
         }
-
+old_gdt:
         /*
          * Initialize the per-CPU GDT with the boot GDT,
          * and set up the GDT descriptor:
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index bce5470ecb4..9466a3c9ff0 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -1056,6 +1056,7 @@ static int __cpuinit __smp_prepare_cpu(int cpu)
         struct warm_boot_cpu_info info;
         struct work_struct task;
         int     apicid, ret;
+        struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
 
         apicid = x86_cpu_to_apicid[cpu];
         if (apicid == BAD_APICID) {
@@ -1063,6 +1064,18 @@ static int __cpuinit __smp_prepare_cpu(int cpu)
                 goto exit;
         }
 
+        /*
+         * the CPU isn't initialized at boot time, allocate gdt table here.
+         * cpu_init will initialize it
+         */
+        if (!cpu_gdt_descr->address) {
+                cpu_gdt_descr->address = get_zeroed_page(GFP_KERNEL);
+                if (!cpu_gdt_descr->address)
+                        printk(KERN_CRIT "CPU%d failed to allocate GDT\n", cpu);
+                        ret = -ENOMEM;
+                        goto exit;
+        }
+
         info.complete = &done;
         info.apicid = apicid;
         info.cpu = cpu;