8857 zio_remove_child() panic due to already destroyed parent zio
illumos/illumos-gate@d6e1c446d7897003fd9fd36ef5aa7da350b7f6af
https://github.com/illumos/illumos-gate/commit/d6e1c446d7897003fd9fd36ef5aa7da350b7f6af
https://www.illumos.org/issues/8857
I had an OS panic on one of our servers: ffffff01809128c0 vpanic() ffffff01809128e0 mutex_panic+0x58(fffffffffb94c904, ffffff597dde7f80) ffffff0180912950 mutex_vector_enter+0x347(ffffff597dde7f80) ffffff01809129b0 zio_remove_child+0x50(ffffff597dde7c58, ffffff32bd901ac0, ffffff3373370908) ffffff0180912a40 zio_done+0x390(ffffff32bd901ac0) ffffff0180912a70 zio_execute+0x78(ffffff32bd901ac0) ffffff0180912b30 taskq_thread+0x2d0(ffffff33bae44140) ffffff0180912b40 thread_start+8() It panicked here: http://src.illumos.org/source/xref/illumos-gate/usr/src/uts/common/fs/zfs/ zio.c#430 pio->io_lock is DEAD, thus a panic. Further analysis shows the "pio" (parent zio of "cio") has already been destroyed.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Youzhong Yang <youzhong@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: George Wilson <george.wilson@delphix.com>