panic in dqflush

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

Could someone please help the x86 illiterate?

I just had a panic at dqflush+0x38 during a quotaoff(8) on 4.0/amd64.

The instruction is
        cmp     %rdi,0x80(%rdx,%rax,8)
and both rdx and rax ar zero.

The source seems to be
        if (dq->dq_ump->um_quotas[dq->dq_type] != vp)
and it looks to me like rdx is dq->dq_ump, rax is dq-dq_type and rdi is vp.
Is this correct?
Sorry, I don't have a dump, only photographs of ddb's show registers.