Re: 2.6.7: preempt + sysfs = BUG on ppc

[Andrew Morton]

Tom Vier <tmv@xxxxxxxxxxx> wrote:
>
> i forgot to exclude /sys when i ran rsync. this is easily reproducable.
> 
>  kernel BUG in fill_read_buffer at fs/sysfs/file.c:92!

Please add this patch, then retest:

--- 25/fs/sysfs/file.c~sysfs-overflow-debug	2004-06-20 14:44:44.272707136 -0700
+++ 25-akpm/fs/sysfs/file.c	2004-06-20 14:48:23.580367304 -0700
@@ -5,6 +5,8 @@
 #include <linux/module.h>
 #include <linux/dnotify.h>
 #include <linux/kobject.h>
+#include <linux/kallsyms.h>
+
 #include <asm/uaccess.h>
 
 #include "sysfs.h"
@@ -83,7 +85,13 @@ static int fill_read_buffer(struct file 
 		return -ENOMEM;
 
 	count = ops->show(kobj,attr,buffer->page);
-	BUG_ON(count > PAGE_SIZE);
+	if (count > PAGE_SIZE) {
+		printk("%s: show handler overrun\n", __FUNCTION__);
+		printk("->show handler: 0x%p",  ops->show);
+		print_symbol(" (%s)", (unsigned long)ops->show);
+		printk("\n");
+		BUG();
+	}
 	if (count >= 0)
 		buffer->count = count;
 	else
_

-
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