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Bug 1321513

Summary: mdadm: failed to read /proc/mdstat while unblocking container
Product: Red Hat Enterprise Linux 6 Reporter: Zhang Yi <yizhan>
Component: mdadmAssignee: Jes Sorensen <Jes.Sorensen>
Status: CLOSED WONTFIX QA Contact: guazhang <guazhang>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 6.8CC: dledford, pawel.baldysiak, tgummels, xni
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-01-05 14:15:51 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Zhang Yi 2016-03-28 06:37:46 UTC
Description of problem:
Testing BZ1320211 found below error output

mdadm: failed to read /proc/mdstat while unblocking container

Version-Release number of selected component (if applicable):
mdadm-3.4-2.el6
2.6.32-634.el6.x86_64

How reproducible:
70%

Steps to Reproduce:
mdadm -CR /dev/md/imsm0 -e imsm -n3 /dev/sd[bcd]
mdadm -CR /dev/md/vol0 -l0 -n2 /dev/sd[bc]
cat /proc/mdstat 
mdadm --wait /dev/md/vol0
mdadm -D /dev/md126 
export MDADM_EXPERIMENTAL=1
mdadm -G /dev/md/imsm0 -n3
sleep 0.5
mdadm -Ss


Actual results:


Expected results:


Additional info:
This issue also can be reproduced with upstream mdadm

+ mdadm -CR /dev/md/imsm0 -e imsm -n3 /dev/sdb /dev/sdc /dev/sdd
mdadm: /dev/sdb appears to contain an ext2fs file system
       size=262144K  mtime=Mon Nov  9 10:42:05 2015
mdadm: /dev/sdb appears to be part of a raid array:
       level=container devices=0 ctime=Thu Jan  1 08:00:00 1970
mdadm: /dev/sdc appears to be part of a raid array:
       level=container devices=0 ctime=Thu Jan  1 08:00:00 1970
mdadm: /dev/sdd appears to be part of a raid array:
       level=container devices=0 ctime=Thu Jan  1 08:00:00 1970
mdadm: container /dev/md/imsm0 prepared.
+ mdadm -CR /dev/md/vol0 -l0 -n2 /dev/sdb /dev/sdc
mdadm: /dev/sdb appears to contain an ext2fs file system
       size=262144K  mtime=Mon Nov  9 10:42:05 2015
mdadm: /dev/sdb appears to be part of a raid array:
       level=container devices=0 ctime=Thu Jan  1 08:00:00 1970
mdadm: partition table exists on /dev/sdb but will be lost or
       meaningless after creating array
mdadm: /dev/sdc appears to be part of a raid array:
       level=container devices=0 ctime=Thu Jan  1 08:00:00 1970
mdadm: partition table exists on /dev/sdc but will be lost or
       meaningless after creating array
mdadm: Creating array inside imsm container md127
mdadm: array /dev/md/vol0 started.
+ cat /proc/mdstat
Personalities : [raid0] [raid6] [raid5] [raid4] 
md126 : active raid0 sdc[1] sdb[0]
      1953518592 blocks super external:/md127/0 128k chunks
      
md127 : inactive sdd[2](S) sdc[1](S) sdb[0](S)
      3315 blocks super external:imsm
       
unused devices: <none>
+ mdadm --wait /dev/md/vol0
+ mdadm -D /dev/md126
/dev/md126:
      Container : /dev/md/imsm0, member 0
     Raid Level : raid0
     Array Size : 1953518592 (1863.02 GiB 2000.40 GB)
   Raid Devices : 2
  Total Devices : 2

          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 128K


           UUID : ecec1252:2e0e4751:bd5f90b5:879242a8
    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
+ export MDADM_EXPERIMENTAL=1
+ MDADM_EXPERIMENTAL=1
+ mdadm -G /dev/md/imsm0 -n3
mdadm: multi-array reshape continues in background
+ sleep 0.5
mdadm: level of /dev/md/vol0 changed to raid4
mdadm: Need to backup 768K of critical section..
+ mdadm -Ss
[root@dhcp-12-163 ~]# mdadm: failed to read /proc/mdstat while unblocking container

Comment 4 Pawel Baldysiak 2016-03-31 20:08:09 UTC
Hello,

This error message is printed by mdadm process that is working in the background during reshape. It tries to unfreeze the container which is already stopped (not exist any longer). We did not observe any other unwanted behavior after applying the patches from: BZ1320211. Currently there is no fix in upstream for this.

Thanks,
Pawel

Comment 7 Jes Sorensen 2017-01-05 14:15:51 UTC
Per Pawel's comments in #4, I am closing this bug.

RHEL6 is in maintenance mode, and there are no other unwanted behaviour.

Closing