If the frontend pass a bad index of production request, the backend will enter an endless loop and then cause a excessive CPU consumption. This issue has been fixed in upstream by: changeset: 391:77f831cbb91d user: Keir Fraser <keir.fraser> date: Fri Jan 18 16:52:25 2008 +0000 summary: blkback: Request-processing loop is unbounded and hence requires a http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/77f831cbb91d changeset: 392:7070d34f251c user: Keir Fraser <keir.fraser> date: Mon Jan 21 11:43:31 2008 +0000 summary: blkback/blktap: Check for kthread_should_stop() in inner loop, http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/7070d34f251c Version-Release number of selected component (if applicable): 2.6.18-194.el5xen How reproducible: Steps to Reproduce: 1. build a guest kernel with the patch attached. 2. run domU with the patched kernel Actual results: Dom0 got hung. Expected results: Dom0 shouldn't be impacted by a bad guest.
This issue has been addressed in following products: Red Hat Enterprise Linux 5 Via RHSA-2011:0004 https://rhn.redhat.com/errata/RHSA-2011-0004.html