Re: BUG #6425: Bus error in slot_deform_tuple

On 2 Feb 2012, at 18:02, Duncan Rance wrote:
>
> At last I have been able to reproduce this problem in a relatively simple (yet contrived) way.

Doh! Should have mentioned this already, but in case a Sparc is not available, the latest on the debugging is as follows:

As well as the bus error, I also saw the same symptom as described in BUG #6200. I changed the four places that did an elog ERROR "invalid memory alloc request size" to PANIC instead and got a raft of core files.

I have not dug any further as yet, but at the following function on the stack:

char *
text_to_cstring(const text *t)

The values t and tunpacked are the same, so pg_detoast_datum_packed() did not modify t. And len comes out as -4.

A couple of bits from dbx:

(dbx) print -fx t->vl_len_[0]
t->vl_len_[0] = 0xffffff84
(dbx) examine tunpacked /2x
0x0000010000ceb9dc: 0x8474 0x776f

Going to have a look further up the stack now.

Cheers,
Dunc