Bug#392986: linux-image-2.6.16-2-em64t-p4-smp: megaraid_sas issues warnings and RESETs
After being advised that upgrading to more recent firmware fixes
this problem, I've installed Dell driver update R149666, which
upgrades the Perc 5i firmware to version v5.1.1-0040. That seems to
solve this problem for me even when I boot back into the unmodified
2.6.16 kernel. I therefore believe that this bug should be considered
a firmware bug instead of a kernel bug, and closed in Debian's BTS.