[BUG report]xfs_btree_make_block_unfull generated an OOPS

[hank peng]

2009/12/15 Dave Chinner <david at fromorbit.com>:
> On Tue, Dec 15, 2009 at 08:49:37AM +0800, hank peng wrote:
>> Hi, Eric:
>> I add some code like this:
>> if (*stat) {
>>                 printk("*stat = 0x%08x, oindex = %p, index = %p\n",
>>                                 *stat, oindex, index);
>>                 if (oindex == NULL || index == NULL) {
>
> This won't catch bad non-NULL pointers like you are seeing.
>
>>                         printk("BUG occured!\n");
>>                         printk("oindex = %p, index = %p\n", oindex, index);
>>                         BUG();
>>                 }
>>                 *oindex = *index = cur->bc_ptrs[level];
>>                 return 0;
>>         }
>>
>> And the same OOPS happened again but a little different, kernel messages are:
>>
>> <snip>
>> *stat = 0x00000001, oindex = e87d7bf8, index = e87d7bfc
>> *stat = 0x00000001, oindex = e87d7bf8, index = e87d7bfc
>> *stat = 0x00000001, oindex = e87d7bf8, index = e87d7bfc
>> *stat = 0x00000001, oindex = e87d7bf8, index = e87d7bfc
>> *stat = 0x00000001, oindex = 00000501, index = 22008424
>> Unable to handle kernel paging request for data at address 0x22008424
>
> Given that oindex and index are stack varibles, this indicates some

In xfs_btree_make_block_unfull, it seems that oindex and index are
optimised to register variables. So, it become more odd.

> thing is probably smashing the stack. Possibly a buffer overrun. To
> narrow down the possible cause, can you add the debug:
>
>        printk("%s:%s: oindex = %p, index = %p\n",
>                        __func__, __LINE__, oindex, index);
>
> throughout the xfs_btree_make_block_unfull() function? i.e. at
> first entry, before the xfs_btree_rshift() call, before the
> xfs_btree_lshift() call, etc, to see if any of the parameters
> are being modified during execution of the function?
>
> If the variables being passed into xfs_btree_make_block_unfull() are
> already bad, then do the same thing for the caller
> xfs_btree_insert(). This may help narrow down where the problem
> is coming from....
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david at fromorbit.com
>



-- 
The simplest is not all best but the best is surely the simplest!