Re: corrupted log causes infinite loop at mount

[Eric Sandeen <sandeen@sandeen.net>]

David Chatterton wrote:
> I assume the loop is further up the chain since kmem_alloc should return NULL
> when asked to alloc 0. So then the problem also lies further up the chain in
> checking for a 0 length before calling down, and/or not assuming we are out of
> memory when xfs_buf_get_noaddr fails.

Well, I set kdb breakpoints, and we only entered xfs_buf_get_noaddr once, so I 
assume it's looping inside.  But I was looking for bugs on, um, another 
filesystem at the time, so didn't investigate much.

I can put it on my list of spare-time bugs to look at, or just thought you guys 
may be interested as well.

-Eric

p.s. ok can't help but look just a bit further...

a test module which does:

int __init test_init(void)
{
         void *data;
         int size = 0;

         data = kmalloc(size, GFP_KERNEL);
         if (data == NULL) {
                 printk("got NULL for alloc return\n");
                 return -1;
         } else {
                 printk("allocated %d bytes at %p\n", size, data);
                 return 0;
         }

}

yields:

allocated 0 bytes at ffff810029d88480

not NULL... nifty eh!

-Eric