This bug has been copied from bug #542954 and has been proposed to be backported to 5.5 z-stream (EUS).
Comment from Kevin, QE please take note and make sure the suggestions made by Kevin are well covered. ======================= Anything that uses lots of synchronous reads/writes (i.e. metadata operations). Long snapshots chains where a lot of COW happens seems to be a good candidate. It's probably enough to test intensively with one backing file format, preferably qcow2 which may issue synchronous metadata I/O again and therefore makes the scenario more complex. For verification of the fix, you need to use virtio-blk (multiple requests running at once are required to even trigger this bug). On the other hand, only IDE can directly call synchronous bdrv_read/write which is touched by this patch, so in order to avoid regressions some tests on IDE should be run, too. Kevin
Tested with the steps in bug #542954, and that issue does not happen on kvm-83-164.el5_5.12. Besides, we will do more test for this bug, and will upload the test result after finished.
Test runners for verifying this bug: https://tcms.engineering.redhat.com/run/10370/ (NFS) https://tcms.engineering.redhat.com/run/10369/ (block device) Result: Passed. kvm version: kvm-83-164.el5_5.12
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 therefore 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-2010-0479.html