Red Hat Bugzilla – Bug 460846
Deadlock possibility with nested LVMs with snapshots
Last modified: 2009-01-20 15:17:25 EST
When using nested LVMs (volume group built from physical devices that are logical devices in another volume group), there is possibility of deadlock in snapshot target because it uses shared mempool. If the upper-layer LVM drains the mempool, the lower layer can deadlock unable to allocate any memory.
It nees to be changed to per-device mempools.
This deadlocky configuration is very unusual, but supported by Red Hat, so it should be fixed.
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
Created attachment 315497 [details]
A patch for the problem. Use per-snapshot mempools.
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 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.