OLVM: I/O issue if direct LUN drived by VirtIO-SCSI with SCSI Pass-Through enabled (Doc ID 2788001.1)

Last updated on OCTOBER 05, 2023

Applies to:

Symptoms

Symptoms could be either one of below or some/all combined:

• VM becomes paused with error message "VM has been paused due to unknown storage error"
• VM hangs under high I/O activity
• With a Device Mapper Multipath device mapped via VirtIO-SCSI with SCSI Pass-Through enabled, I/O only go through one path constantly
• Below call trace found inside VM:

Jun 3 06:02:36 olvm-vm kernel: INFO: task ora_task:1905 blocked for more than 122 seconds.
Jun 3 06:02:36 olvm-vm kernel: Tainted: P O 5.4.17-2102.200.13.el7uek.x86_64 #2
Jun 3 06:02:36 olvm-vm kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Jun 3 06:02:36 olvm-vm kernel: ora_task D 0 1905 1 0x00000080
Jun 3 06:02:36 olvm-vm kernel: Call Trace:
Jun 3 06:02:36 olvm-vm kernel: __schedule+0x2bc/0x599
Jun 3 06:02:36 olvm-vm kernel: schedule+0x3e/0x9a
Jun 3 06:02:36 olvm-vm kernel: io_schedule+0x16/0x39
Jun 3 06:02:36 olvm-vm kernel: __blkdev_direct_IO_simple+0x20f/0x2e1
Jun 3 06:02:36 olvm-vm kernel: ? blkdev_iopoll+0x40/0x31
Jun 3 06:02:36 olvm-vm kernel: blkdev_direct_IO+0x42b/0x493
Jun 3 06:02:36 olvm-vm kernel: ? current_time+0x41/0x78
Jun 3 06:02:36 olvm-vm kernel: ? atime_needs_update+0x6c/0xca
Jun 3 06:02:36 olvm-vm kernel: ? touch_atime+0x33/0xca
Jun 3 06:02:36 olvm-vm kernel: generic_file_read_iter+0x8d/0x13a
Jun 3 06:02:36 olvm-vm kernel: blkdev_read_iter+0x37/0x3a
Jun 3 06:02:36 olvm-vm kernel: new_sync_read+0x11a/0x1be
Jun 3 06:02:36 olvm-vm kernel: __vfs_read+0x29/0x34
Jun 3 06:02:36 olvm-vm kernel: vfs_read+0x8e/0x138
Jun 3 06:02:36 olvm-vm kernel: ksys_pread64+0x69/0x94
Jun 3 06:02:36 olvm-vm kernel: __x64_sys_pread64+0x1e/0x20
Jun 3 06:02:36 olvm-vm kernel: do_syscall_64+0x60/0x1d9
Jun 3 06:02:36 olvm-vm kernel: entry_SYSCALL_64_after_hwframe+0x170/0x0
Jun 3 06:02:36 olvm-vm kernel: RIP: 0033:0x7f5db2ce9fa3
Jun 3 06:02:36 olvm-vm kernel: Code: Bad RIP value.
Jun 3 06:02:36 olvm-vm kernel: RSP: 002b:00007ffdcb704728 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
Jun 3 06:02:36 olvm-vm kernel: RAX: ffffffffffffffda RBX: 00007ffdcb70a7a8 RCX: 00007f5db2ce9fa3
Jun 3 06:02:36 olvm-vm kernel: RDX: 0000000000004000 RSI: 00007f5db1771000 RDI: 0000000000000100
Jun 3 06:02:36 olvm-vm kernel: RBP: 00007ffdcb709130 R08: 00007ffdcb704710 R09: 00007ffdcb7e20b0
Jun 3 06:02:36 olvm-vm kernel: R10: 0000000001804000 R11: 0000000000000246 R12: 0000000000000200
Jun 3 06:02:36 olvm-vm kernel: R13: 0000026a60d85478 R14: 0000000000000000 R15: 00007f5db17e1000

Changes

By adding a direct LUN drived by VirtIO-SCSI, the "Enable SCSI Pass-Through" is checked by default, which should not be as it is under technical preview at the time of writing.

Cause

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