2.6 /proc/interrupts fails on systems with many CPUs

[Erik Jacobson]

Howdy.

On systems with lots of processors (512 for example), catting /proc/interrupts
fails with a "not enough memory" error.

This was observed in 2.6.0-test8

I tracked this down to this in proc_misc.c:

static int interrupts_open(struct inode *inode, struct file *file)
{
   unsigned size = 4096 * (1 + num_online_cpus() / 8);
   char *buf = kmalloc(size, GFP_KERNEL);

The kmalloc fails here.

I'm looking for suggestions on how to fix this.  I came up with one fix
that seems to work OK for ia64.  I have attached it to this message.
I'm looking for advice on what should be proposed for the real fix.

Thanks!

--
Erik Jacobson - Linux System Software - Silicon Graphics - Eagan, Minnesota
===========================================================================
linux/fs/proc/proc_misc.c
===========================================================================

--- /usr/tmp/TmpDir.18901-0/linux/fs/proc/proc_misc.c_1.52	Tue Nov 11 09:55:19 2003
+++ linux/fs/proc/proc_misc.c	Tue Nov 11 09:43:32 2003
@@ -445,7 +445,7 @@
 	/* don't ask for more than the kmalloc() max size, currently 128 KB */
 	if (size > 128 * 1024)
 		size = 128 * 1024;
-	buf = kmalloc(size, GFP_KERNEL);
+	buf = __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -476,20 +476,21 @@
 extern int show_interrupts(struct seq_file *p, void *v);
 static int interrupts_open(struct inode *inode, struct file *file)
 {
-	unsigned size = 4096 * (1 + num_online_cpus() / 8);
-	char *buf = kmalloc(size, GFP_KERNEL);
+	unsigned size = 4096 * (1 + num_online_cpus() / 8); 
+	char *buf = __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 	struct seq_file *m;
 	int res;
 
-	if (!buf)
+	if (!buf) 
 		return -ENOMEM;
+	
 	res = single_open(file, show_interrupts, NULL);
 	if (!res) {
 		m = file->private_data;
 		m->buf = buf;
 		m->size = size;
 	} else
-		kfree(buf);
+		vfree(buf);
 	return res;
 }
 static struct file_operations proc_interrupts_operations = {

===========================================================================
linux/fs/seq_file.c
===========================================================================

--- /usr/tmp/TmpDir.18901-0/linux/fs/seq_file.c_1.8	Tue Nov 11 09:55:19 2003
+++ linux/fs/seq_file.c	Tue Nov 11 09:18:06 2003
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
@@ -29,6 +30,7 @@
 int seq_open(struct file *file, struct seq_operations *op)
 {
 	struct seq_file *p = kmalloc(sizeof(*p), GFP_KERNEL);
+
 	if (!p)
 		return -ENOMEM;
 	memset(p, 0, sizeof(*p));
@@ -61,7 +63,7 @@
 	down(&m->sem);
 	/* grab buffer if we didn't have one */
 	if (!m->buf) {
-		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
+		m->buf = __vmalloc(m->size = PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 		if (!m->buf)
 			goto Enomem;
 	}
@@ -94,8 +96,8 @@
 		if (m->count < m->size)
 			goto Fill;
 		m->op->stop(m, p);
-		kfree(m->buf);
-		m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
+		vfree(m->buf);
+		m->buf = __vmalloc(m->size <<= 1, GFP_KERNEL, PAGE_KERNEL);
 		if (!m->buf)
 			goto Enomem;
 		m->count = 0;
@@ -160,7 +162,7 @@
 	if (!offset)
 		return 0;
 	if (!m->buf) {
-		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
+		m->buf = __vmalloc(m->size = PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
 		if (!m->buf)
 			return -ENOMEM;
 	}
@@ -192,8 +194,8 @@
 
 Eoverflow:
 	m->op->stop(m, p);
-	kfree(m->buf);
-	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
+	vfree(m->buf);
+	m->buf = __vmalloc(m->size <<= 1, GFP_KERNEL, PAGE_KERNEL);
 	return !m->buf ? -ENOMEM : -EAGAIN;
 }
 
@@ -246,7 +248,7 @@
 int seq_release(struct inode *inode, struct file *file)
 {
 	struct seq_file *m = (struct seq_file *)file->private_data;
-	kfree(m->buf);
+	vfree(m->buf);
 	kfree(m);
 	return 0;
 }