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Oracle Linux 6: Server Panic While Running actifio sky backup (Doc ID 2495444.1)

Last updated on JANUARY 29, 2020

Applies to:

Linux OS - Version Oracle Linux 6.9 with Unbreakable Enterprise Kernel [4.1.12] and later
Information in this document applies to any platform.


Oracle Linux 6 server reboots after running the actifio sky backup on Exadata setup. On the vmcore file the below call traces are seen:

KERNEL: /share/linuxrpm/vmlinux_repo/64/nano/4.1.12-94.7.1.el6uek.x86_64/vmlinux
    DUMPFILE: xx.vmcore  [PARTIAL DUMP]
        CPUS: 48
        DATE: Wed Sep 12 18:31:50 2018
      UPTIME: 22 days, 23:54:55
LOAD AVERAGE: 4.15, 3.76, 4.49
       TASKS: 4178
     RELEASE: 4.1.12-94.7.1.el6uek.x86_64
     VERSION: #2 SMP Thu Sep 28 08:54:39 PDT 2017
     MACHINE: x86_64  (2693 Mhz)
      MEMORY: 256 GB
       PANIC: "BUG: unable to handle kernel NULL pointer dereference at 0000000000000040"
         PID: 302211
     COMMAND: "kworker/u96:1"
        TASK: ffff882551e68000  [THREAD_INFO: ffff88278b7c8000]
         CPU: 19

crash64> bt
PID: 302211  TASK: ffff882551e68000  CPU: 19  COMMAND: "kworker/u96:1"
 #0 [ffff88278b7cb960] machine_kexec at ffffffff8105e2e0
 #1 [ffff88278b7cb9d0] crash_kexec at ffffffff81112cd8
 #2 [ffff88278b7cbaa0] oops_end at ffffffff8101a7f8
 #3 [ffff88278b7cbad0] no_context at ffffffff8106d971
 #4 [ffff88278b7cbb20] __bad_area_nosemaphore at ffffffff8106db6d
 #5 [ffff88278b7cbb70] bad_area_nosemaphore at ffffffff8106dc83
 #6 [ffff88278b7cbb80] __do_page_fault at ffffffff8106e208
 #7 [ffff88278b7cbbf0] do_page_fault at ffffffff8106e517
 #8 [ffff88278b7cbc30] page_fault at ffffffff816ba3e8
    [exception RIP: sysfs_do_create_link_sd+71]
    RIP: ffffffff8128d5b7  RSP: ffff88278b7cbce8  RFLAGS: 00010246
    RAX: 00000000b81ab81a  RBX: ffffffff819862fd  RCX: 0000000000000001
    RDX: 000000000000b81a  RSI: 0000000000000010  RDI: ffffffff820577a8
    RBP: ffff88278b7cbd18   R8: ffff881d20cddf18   R9: ffff88407e802400
    R10: ffffffff813244cf  R11: 0000000000000282  R12: ffff8820215cbbb8
    R13: 0000000000000010  R14: 0000000000000001  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #9 [ffff88278b7cbd20] sysfs_create_link at ffffffff8128d6b6
#10 [ffff88278b7cbd30] add_disk at ffffffff81308caa
#11 [ffff88278b7cbd70] sd_probe_async at ffffffffa008be61 [sd_mod]
#12 [ffff88278b7cbdb0] async_run_entry_fn at ffffffff810a94fa
#13 [ffff88278b7cbde0] process_one_work at ffffffff810a1521
#14 [ffff88278b7cbe40] worker_thread at ffffffff810a19a0
#15 [ffff88278b7cbec0] kthread at ffffffff810a6b7e
#16 [ffff88278b7cbf50] ret_from_fork at ffffffff816b8462

A task  is adding a sysfs entry for a new iscsi LUN is racing with this task that is removing a sysfs entry:
The task has this file open:
15 ffff880ab193cd00 ffff8816d4c4af00 ffff8810b68024a8 REG  

PID: 371226  TASK: ffff881bd1bf0e00  CPU: 20  COMMAND: "udsagent"
 #0 [ffff881f643efc18] __schedule at ffffffff816b3752
 #1 [ffff881f643efc70] schedule at ffffffff816b3e1e
 #2 [ffff881f643efc90] blk_mq_freeze_queue_wait at ffffffff8130095d
 #3 [ffff881f643efcf0] blk_freeze_queue at ffffffff813016fe
 #4 [ffff881f643efd10] blk_cleanup_queue at ffffffff812f4c14
 #5 [ffff881f643efd50] __scsi_remove_device at ffffffff814adaaa
 #6 [ffff881f643efd70] scsi_remove_device at ffffffff814adb60
 #7 [ffff881f643efd90] sdev_store_delete at ffffffff814adbb1
 #8 [ffff881f643efdb0] dev_attr_store at ffffffff81464180
 #9 [ffff881f643efdc0] sysfs_kf_write at ffffffff8128c831
#10 [ffff881f643efdd0] kernfs_fop_write at ffffffff8128c2a9
#11 [ffff881f643efe20] __vfs_write at ffffffff8120c1e4
#12 [ffff881f643efec0] vfs_write at ffffffff8120c46b
#13 [ffff881f643eff00] sys_write at ffffffff8120c5c6
#14 [ffff881f643eff50] system_call_fastpath at ffffffff816b806e




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