https://bugs.freedesktop.org/show_bug.cgi?id=34030
--- Comment #1 from Pavel Ondračka pavel.ondracka@email.cz 2011-02-08 04:17:13 PST --- Created an attachment (id=43093) --> (https://bugs.freedesktop.org/attachment.cgi?id=43093) screenshot without corruption for comparison
BTW reverting 8f32c6cfc6503dd234f09fb06941803866c23c65 from current mesa master makes the problem go away.