In write operation dm-crypt needs to allocate new bio request and run crypto operation on this clone. Cloned request has always the same size, but number of physical segments can be increased and violate max_phys_segments restriction. This can lead to data corruption and serious hardware malfunction. See http://www2.kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/dm-crypt-use-bio_add_page.patch
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
Fix is upstream - commit 91e106259214b40e992a58fb9417da46868e19b2
in 2.6.18-62.el5 You can download this test kernel from http://people.redhat.com/dzickus/el5
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2008-0314.html