Bug 612248

Summary: splitting off the last mirror image causes error messages
Product: Red Hat Enterprise Linux 6 Reporter: Corey Marthaler <cmarthal>
Component: lvm2Assignee: Jonathan Earl Brassow <jbrassow>
Status: CLOSED CURRENTRELEASE QA Contact: Corey Marthaler <cmarthal>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.0CC: agk, dwysocha, heinzm, jbrassow, joe.thornber, mbroz, prajnoha, prockai
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: lvm2-2.02.72-2.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2010-11-10 21:08:20 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:

Description Corey Marthaler 2010-07-07 16:35:24 UTC 
Description of problem:
[root@grant-02 ~]# lvs -a -o +devices
  LV                VG         Attr   LSize   Log         Copy%  Convert Devices
  mirror            grant      mwi-a- 100.00m mirror_mlog 100.00         mirror_mimage_0(0),mirror_mimage_1(0),mirror_mimage_2(0)
  [mirror_mimage_0] grant      iwi-ao 100.00m                            /dev/sdb1(0)
  [mirror_mimage_1] grant      iwi-ao 100.00m                            /dev/sdb2(0)
  [mirror_mimage_2] grant      iwi-ao 100.00m                            /dev/sdc1(0)
  [mirror_mlog]     grant      lwi-ao   4.00m                            /dev/sdc2(0)

[root@grant-02 ~]# lvconvert --splitmirrors 1 --name newA grant/mirror /dev/sdc1
  Logical volume mirror converted.

[root@grant-02 ~]# lvs -a -o +devices
  LV                VG         Attr   LSize   Log         Copy%  Convert Devices
  mirror            grant      mwi-a- 100.00m mirror_mlog 100.00         mirror_mimage_0(0),mirror_mimage_1(0)
  [mirror_mimage_0] grant      iwi-ao 100.00m                            /dev/sdb1(0)
  [mirror_mimage_1] grant      iwi-ao 100.00m                            /dev/sdb2(0)
  [mirror_mlog]     grant      lwi-ao   4.00m                            /dev/sdc2(0)
  newA              grant      -wi-a- 100.00m                            /dev/sdc1(0)

[root@grant-02 ~]# lvconvert --splitmirrors 1 --name newB grant/mirror /dev/sdb2
  Internal error: _memlock_count has dropped below 0.
  Internal error: _memlock_count has dropped below 0.
  Logical volume mirror converted.

[root@grant-02 ~]# lvs -a -o +devices
  LV      VG         Attr   LSize   Log Copy%  Convert Devices
  mirror  grant      -wi-a- 100.00m                    /dev/sdb1(0)
  newA    grant      -wi-a- 100.00m                    /dev/sdc1(0)
  newB    grant      -wi-a- 100.00m                    /dev/sdb2(0)


Version-Release number of selected component (if applicable):
lvm2-2.02.69-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
lvm2-libs-2.02.69-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
lvm2-cluster-2.02.69-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
device-mapper-1.02.51-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
device-mapper-libs-1.02.51-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
device-mapper-event-1.02.51-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
device-mapper-event-libs-1.02.51-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010
cmirror-2.02.69-2.el6    BUILT: Fri Jul  2 07:26:01 CDT 2010

How reproducible:
everytime
Comment 1 Peter Rajnoha 2010-07-09 12:01:48 UTC 
(In reply to comment #0)
> [root@grant-02 ~]# lvconvert --splitmirrors 1 --name newB grant/mirror
> /dev/sdb2
>   Internal error: _memlock_count has dropped below 0.
>   Internal error: _memlock_count has dropped below 0.
>   Logical volume mirror converted.

Well, in this case, while splitting off the mirror in _split_mirror_image fn, a suspend is called for the original device tree as a whole. This calls just one memlock_inc internally for the tree.

When trying to resume particular devices (not the whole tree) just after that, memlock_dec gets called as many times as the resume is called, resulting in that _memlock_count to drop below 0...
Comment 3 Jonathan Earl Brassow 2010-07-12 14:31:02 UTC 
Preliminary patch sent to lvm-devel
Comment 4 Jonathan Earl Brassow 2010-07-13 21:55:08 UTC 
pending version 2.02.71
Comment 5 RHEL Program Management 2010-07-15 13:58:31 UTC 
This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release. It has
been denied for the current Red Hat Enterprise Linux release.

** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **
Comment 8 Corey Marthaler 2010-07-28 23:07:20 UTC 
Fix verified in the latest build.

2.6.32-52.el6.x86_64

lvm2-2.02.72-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
lvm2-libs-2.02.72-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
lvm2-cluster-2.02.72-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
udev-147-2.21.el6    BUILT: Mon Jul 12 04:55:00 CDT 2010
device-mapper-1.02.53-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
device-mapper-libs-1.02.53-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
device-mapper-event-1.02.53-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
device-mapper-event-libs-1.02.53-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
cmirror-2.02.72-3.el6    BUILT: Wed Jul 28 15:39:43 CDT 2010
Comment 9 releng-rhel@redhat.com 2010-11-10 21:08:20 UTC 
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.