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