2.5.2: swapon failing with errno=0 (sys_swapon)

[Alex Riesen]

Tried to use 2.5.2. And got the message from swapon:
swapon: /dev/hda6: Success

strace showed some strange return value from swapon(2),
looking like a pointer.

The patch will cure the problem, though i'm not sure
about the reasons setting the error to pointer.
Are the kernel pointers handled specially in errors?
-alex

--- linux/mm/swapfile.c Mon Jan 14 18:38:36 2002
+++ linux/mm/swapfile.c-        Thu Jan 17 08:50:28 2002
@@ -904,7 +904,7 @@
        swap_file = filp_open(name, O_RDWR, 0);
        putname(name);
        error = PTR_ERR(swap_file);
-       if (error)
+       if (IS_ERR(swap_file))
                goto bad_swap_2;
 
        p->swap_file = swap_file;