Red Hat Bugzilla – Bug 445054
8250 serial port lock recursion
Last modified: 2009-05-18 15:33:32 EDT
Description of problem:
Customer is running EL4.5 as a HVM guest under Xen, using a terminal window and
xm console to connect to the virtual serial console of the vm. When the user
pastes a large amount of text (>512 bytes) into the console window, the guest
kernel panics (UP) or deadlocks (SMP).
The bug is due to a recursive lock request caused by not releasing the port lock
This is the same problem as reported upstream, with a fix posted here:
The second part of this fix was introduced in el4.5 but the first part was
missed. However, the first part is needed as well.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. start a xen hvm guest running the el 4.5 kernel
2. connect to the guest console with the command "xm console <domain>"
3. copy and paste more than 512 bytes into the console window
guest kernel panic or deadlock
no guest kernel panic or deadlock
Created attachment 304435 [details]
panic stack trace
Created attachment 304436 [details]
fix for recursive lock request in 8250.c
Can't seem to get to the link above.
The second part of the patch was submitted by Aris .. cc'ing him on this BZ.
The first part of the patch makes sense and IMO is stable enough to be included.
I'll create a patch and test.
Sorry -- wrong link:
Created attachment 304667 [details]
RHEL4 fix for this issue
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
Updating PM score.
Committed in 78.9.EL . RPMS are available at http://people.redhat.com/vgoyal/rhel4/
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.