Bug 210453

Summary:	gnbd handles signals outside process context
Product:	[Retired] Red Hat Cluster Suite	Reporter:	Bryn M. Reeves <bmr>
Component:	gnbd	Assignee:	Ben Marzinski <bmarzins>
Status:	CLOSED ERRATA	QA Contact:	Cluster QE <mspqa-list>
Severity:	high	Docs Contact:
Priority:	medium
Version:	4	CC:	cluster-maint, tao
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	RHBA-2007-0144	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2007-05-10 21:06:11 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	215099

Description Bryn M. Reeves 2006-10-12 08:26:40 UTC

Description of problem:
Processes accessing a GFS filesystem backed by gnbd devices become stuck in D
state. 

At the time of the hangs messages appear on the client nodes from gnbd:

Sep  4 14:06:01 HPC2 sshd(pam_unix)[18706]: session closed for user jopan
Sep  4 14:08:54 HPC2 kernel: gnbd (pid 18821: MakeNearBnBtJPE) got signal 9
Sep  4 14:08:54 HPC2 kernel: gnbd5: Send control failed (result -4)
Sep  4 14:10:17 HPC2 sshd(pam_unix)[18844]: session opened for user jopan by (uid=0)
Sep  4 14:10:19 HPC2 sshd(pam_unix)[18844]: session closed for user jopan

It looks like sock_xmit is being called via do_gnbd_request and gnbd_send_req
outside process context (softirq?).

At this time, current evaluates to the last process to be scheduled instead of
the gnbd thread. If the process happens to have a signal pending when we return
from sock_sendmsg, sock_xmit incorrectly dequeues it and returns -EINTR.

We should only attempt signal handling when running in the context of the gnbd
thread.

Comment 5 Red Hat Bugzilla 2007-05-10 21:06:11 UTC

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-2007-0144.html