• Icon: Bug Bug
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    • rhel-9.5
    • qemu-kvm
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    • rhel-sst-virtualization-hwe
    • ssg_virtualization
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    • False
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    • Red Hat Enterprise Linux
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    • s390x
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      What were you trying to do that didn't work?

      Use the VM after a live dump.

      Please provide the package NVR for which bug is seen:

      qemu-kvm-9.0.0-10.el9_5.s390x

      How reproducible:

      10% if running a specific automated test case
      0% when trying manually or with a bash script

      Steps to reproduce

      1. Take a live dump
        virsh dump --live avocado-vt-vm1 vm_dump
      2. Access the VM via ssh or serial console

      Expected results

      I can log into the VM and use it as usual.

      Actual results

      I can't establish an ssh connection although this worked before the dump. The serial console doesn't show any output.

      Additional info

      1. The disk is a qcow2 image attached via virtio-blk and a default installation with lvm
      2. The mentioned test case is tp-libvirt virsh.domjobinfo.normal_test.dump_action.live_dump.running_state.vm_id
      3. Attaching dmesg and back traces for tasks in uninterruptible state
      4. This is not a regression, since RHEL 8.8 it's been happening a few times.
      5. I've seen similar hangs in cases of external live snapshots memory spec. Ref. RHEL-52635, more specifically this one:
        PID: 25       TASK: 720000            CPU: 1    COMMAND: "kworker/u10:0"
         #0 [37fffbf3578] __schedule at 3d3015c0
         #1 [37fffbf35f8] schedule at 3d3018e6
         #2 [37fffbf3628] io_schedule at 3d301a32
         #3 [37fffbf3658] rq_qos_wait at 3ce44800
         #4 [37fffbf36f8] wbt_wait at 3ce6eba8
         #5 [37fffbf3750] __rq_qos_throttle at 3ce4430e
         #6 [37fffbf3788] blk_mq_submit_bio at 3ce34068
         #7 [37fffbf3818] __submit_bio_noacct at 3ce2211c
         #8 [37fffbf3868] iomap_submit_ioend at 3cd2f48e
         #9 [37fffbf38a8] xfs_vm_writepages at 3ff7fd107ca [xfs]
        #10 [37fffbf3950] do_writepages at 3cbb3692
        #11 [37fffbf39d0] __writeback_single_inode at 3cce534c
        #12 [37fffbf3a28] writeback_sb_inodes at 3cce5c5c
        #13 [37fffbf3b20] __writeback_inodes_wb at 3cce601a
        #14 [37fffbf3b80] wb_writeback at 3cce635e
        #15 [37fffbf3c30] wb_workfn at 3cce76e8
        #16 [37fffbf3d10] process_one_work at 3c9ac892
        #17 [37fffbf3d98] worker_thread at 3c9ad77e
        #18 [37fffbf3e10] kthread at 3c9b6b40
        #19 [37fffbf3e68] __ret_from_fork at 3c936ebc
        #20 [37fffbf3e98] ret_from_fork at 3d308bf2
        

        1. kworker_80
          1 kB
        2. kworker_8
          0.7 kB
        3. kworker_76
          1 kB
        4. kworker_64
          1 kB
        5. kworker_624
          1 kB
        6. kworker_53
          1 kB
        7. kworker_32
          1 kB
        8. kworker_2905
          1 kB
        9. kworker_2903
          1 kB
        10. kworker_2902
          1 kB
        11. kworker_2901
          1 kB
        12. kworker_25
          1 kB
        13. kworker_24
          0.5 kB
        14. kworker_221
          1 kB
        15. dracut_install_2900
          1 kB
        16. dmesg
          22 kB
        17. agetty_868
          1 kB
        18. agetty_2918
          1 kB

              virt-maint virt-maint
              smitterl@redhat.com Sebastian Mitterle
              virt-maint virt-maint
              Sebastian Mitterle Sebastian Mitterle
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                Created:
                Updated: