'BUG: soft lockup' can be displayed in a system made up of multipath

Solution Verified - Updated -

Issue

  • The following message can occasionally be displayed when a test set is executed in a system made up of multipath.
    "kernel: BUG:soft lockup - CPU#0 stuck for 10s! [kblockd/0:615]"
    
  • The system was constructed by the following procedures.
    1. Change /etc/modprobe.conf. (a snippet of the updated portion)
        options scsi_mod max_luns=512
        options lpfc lpfc_lun_queue_depth=8 lpfc_link_speed=8 lpfc_topology=2 
    
      2. Create a new initrd.
        cp /boot/initrd-2.6.18-164.10.1.el5.img /boot/initrd-2.6.18-164.10.1.el5.img.bak
        mkinitrd -f /boot/initrd-2.6.18-164.10.1.el5_new.img 2.6.18-164.10.1.el5
    
      3. Change /boot/grub/grub.conf. (a snippet of the updated portion)
        #initrd /initrd-2.6.18-164.10.1.el5.img
        initrd /initrd-2.6.18-164.10.1.el5_new.img
    
      4. Reboot the system.
    
      5. Change /etc/multipath.conf. (a snippet of the updated portion)
        The following configuration is indicated by IBM when VS850 is used on RHEL5.
    
        blacklist {
             wwid "3500000*"
        }
        defaults {
             polling_interval 30
             failback immediate
             no_path_retry 5
             rr_min_io 100
             path_checker tur
             user_friendly_names yes
        }
        device {
             vendor                   "IBM"
             product                  "2145"
             path_grouping_policy     group_by_prio
             prio_callout             "/sbin/mpath_prio_alua /dev/%n"
        }
    
      6. Create multipath and activate multipathd.
        multipath -v 1
        chkconfig --add multipathd
        chkconfig multipathd on
        multipath
        /etc/init.d/multipathd start
    
      7. Confirm the LUN Mapping.
        multipath -ll -> 64 LUNs were confirmed.
    
      8. Excute the test set all the time.
    
      9. "BUG:soft lockup" can be displayed several times per hour.
    
      * "BUG:soft lockup" isn't displayed when the test set is
        executed all the time after changing /etc/multipath.conf as follows.
        Changed parts are indicated as *.
        -----old
         device {
              vendor                   "IBM"
              product                  "2145"
        *     path_grouping_policy     group_by_prio
        *     prio_callout             "/sbin/mpath_prio_alua /dev/%n"
         }
        -----new
         device {
              vendor                   "IBM"
              product                  "2145"
        *     path_grouping_policy     multibus
         }
    

Environment

  • Red Hat Enterprise Linux Version 5
  • Kernel Version: 2.6.18-164.10.1.el5
  • device-mapper-1.02.32-1.el5
  • device-mapper-event-1.02.32-1.el5
  • device-mapper-multipath-0.4.7-30.el5_4.4

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