Comment # 3 on bug 1226443 from Dmitry Kobelev

Backtrace from kernel dump #1:
PID: 22156    TASK: ffff9f3290050000  CPU: 1    COMMAND: "kworker/1:0"
 #0 [ffffc29c00180c00] machine_kexec at ffffffffb2e903ef
 #1 [ffffc29c00180c58] __crash_kexec at ffffffffb2fbfeae
 #2 [ffffc29c00180d18] crash_kexec at ffffffffb2fc03d4
 #3 [ffffc29c00180d20] oops_end at ffffffffb2e48c84
 #4 [ffffc29c00180d40] page_fault_oops at ffffffffb2ea3839
 #5 [ffffc29c00180dc8] exc_page_fault at ffffffffb3b00e63
 #6 [ffffc29c00180df0] asm_exc_page_fault at ffffffffb3c012a6
    [exception RIP: rb_first+15]
    RIP: ffffffffb3a8c8ff  RSP: ffffc29c00180ea0  RFLAGS: 00210202
    RAX: 0000000000000057  RBX: ffff9f339ded76d8  RCX: 00000000010000d1
    RDX: 0000000000000057  RSI: 0000000000000000  RDI: ffff9f326ec65128
    RBP: ffff9f339ded7660   R8: ffff9f32f1c43700   R9: 00000000010000d1
    R10: 00000000010000d1  R11: 0000000000000001  R12: 0000000000000000
    R13: ffff9f326ec65128  R14: 000000000000000a  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffffc29c00180ea0] simple_xattrs_free at ffffffffb324daf9
 #8 [ffffc29c00180ec8] kernfs_free_rcu at ffffffffb32d7a2f
 #9 [ffffc29c00180ee0] rcu_do_batch at ffffffffb2f7660f
#10 [ffffc29c00180f58] rcu_core at ffffffffb2f79bd9
#11 [ffffc29c00180fa0] handle_softirqs at ffffffffb2ec96cf
#12 [ffffc29c00180ff0] do_softirq at ffffffffb2ec93bb
--- <IRQ stack> ---
    [exception RIP: unknown or invalid address]
    RIP: ffff9f327af3bf80  RSP: ffffffffb2ef228f  RFLAGS: ffffffffb2ee8030
    RAX: ffff9f32f4e23cc0  RBX: ffff9f34adabba00  RCX: ffffffffb2ee8321
    RDX: ffff9f327af3bf80  RSI: ffff9f33008ce540  RDI: ffff9f3290050000
    RBP: ffff9f324103c605   R8: ffff9f32f4e23d00   R9: ffff9f34adabba00
    R10: 61c8864680b583eb  R11: ffff9f34adabba28  R12: ffffffffb2ee700d
    R13: ffff9f3290050000  R14: ffff9f34adabba00  R15: ffff9f324103c600
    ORIG_RAX: ffffc29c107afda0  CS: ffff9f32f4e23cc0  SS: ffffc29c06b1ff48
bt: WARNING: possibly bogus exception frame
#14 [ffffc29c06b1ff20] ret_from_fork at ffffffffb2e52ce1
#15 [ffffc29c06b1ff40] ret_from_fork_asm at ffffffffb2e044aa

---
#2:
PID: 1        TASK: ffff8a4480b10000  CPU: 5    COMMAND: "systemd"
 #0 [ffffa6bf400338d0] machine_kexec at ffffffff868903ef
 #1 [ffffa6bf40033928] __crash_kexec at ffffffff869bfeae
 #2 [ffffa6bf400339e8] crash_kexec at ffffffff869c03d4
 #3 [ffffa6bf400339f0] oops_end at ffffffff86848c84
 #4 [ffffa6bf40033a10] page_fault_oops at ffffffff868a3839
 #5 [ffffa6bf40033a98] exc_page_fault at ffffffff87500e63
 #6 [ffffa6bf40033ac0] asm_exc_page_fault at ffffffff876012a6
    [exception RIP: simple_xattr_set+107]
    RIP: ffffffff86c4d75b  RSP: ffffa6bf40033b78  RFLAGS: 00010202
    RAX: 0000000000000000  RBX: 0000000000000026  RCX: 0000000000000000
    RDX: 00000000000000ff  RSI: ffffa6bf40033c98  RDI: ffff8a4481dab270
    RBP: ffffa6bf40033c98   R8: 0000000000000002   R9: 0000000000000000
    R10: ffffa6bf40033c98  R11: 0000000000000002  R12: 0000000000000000
    R13: ffff8a4481dab268  R14: 0000000000000002  R15: ffff8a4481dab270
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffffa6bf40033ba8] kernfs_vfs_user_xattr_set at ffffffff86cd6e11
 #8 [ffffa6bf40033bd8] __vfs_removexattr at ffffffff86c4b790
 #9 [ffffa6bf40033c18] __vfs_removexattr_locked at ffffffff86c4bc8b
#10 [ffffa6bf40033c50] vfs_removexattr at ffffffff86c4bd88
#11 [ffffa6bf40033c90] removexattr at ffffffff86c4beb7
#12 [ffffa6bf40033db0] path_removexattr at ffffffff86c4bff4
#13 [ffffa6bf40033df0] __x64_sys_removexattr at ffffffff86c4c04b
#14 [ffffa6bf40033df8] do_syscall_64 at ffffffff874f94b2
#15 [ffffa6bf40033f40] entry_SYSCALL_64_after_hwframe at ffffffff8760012f
    [exception RIP: unknown or invalid address]
    RIP: 0000000000000246  RSP: 0000000000000000  RFLAGS: 0000002b
    RAX: 0000000000000000  RBX: 0000563b51aae560  RCX: 00007f6d9095f2cc
    RDX: 0000563b51aae560  RSI: 00000000000000c5  RDI: 00007f6d901112db
    RBP: 0000000000000246   R8: 00007f6d901112db   R9: ffffffffffffffda
    R10: 0000563b51744010  R11: 0000000000000000  R12: 0000000000000000
    R13: 00007f6d9095f2cc  R14: 00007f6d9095f2cc  R15: 0000000000000003
    ORIG_RAX: 0000000000000033  CS: 7ffc5c4dd208  SS: 0000
bt: WARNING: possibly bogus exception frame