[PATCH] x86_64: Remove excessive stack allocation in MCE code with large NR_CPUS

Remove excessive stack allocation in MCE code with large NR_CPUS

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c
index 6ca066424dee..3a89d735a4f6 100644
--- a/arch/x86_64/kernel/mce.c
+++ b/arch/x86_64/kernel/mce.c
@@ -379,18 +379,23 @@ static void collect_tscs(void *data)
 
 static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize, loff_t *off)
 {
-        unsigned long cpu_tsc[NR_CPUS];
+        unsigned long *cpu_tsc;
         static DECLARE_MUTEX(mce_read_sem);
         unsigned next;
         char __user *buf = ubuf;
         int i, err;
 
+        cpu_tsc = kmalloc(NR_CPUS * sizeof(long), GFP_KERNEL);
+        if (!cpu_tsc)
+                return -ENOMEM;
+
         down(&mce_read_sem); 
         next = rcu_dereference(mcelog.next);
 
         /* Only supports full reads right now */
         if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) { 
                 up(&mce_read_sem);
+                kfree(cpu_tsc);
                 return -EINVAL;
         }
 
@@ -421,6 +426,7 @@ static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize, loff
                 }
         }       
         up(&mce_read_sem);
+        kfree(cpu_tsc);
         return err ? -EFAULT : buf - ubuf; 
 }