# mdb -k
[...]

> ::pgrep zpool | ::walk thread | ::findstack
stack pointer for thread ffffff01fa4fe080: ffffff000863bb00
[ ffffff000863bb00 _resume_from_idle+0xf1() ]
  ffffff000863bb40 swtch+0x17f()
  ffffff000863bb70 cv_wait+0x61()
  ffffff000863bbe0 spa_scrub+0x96()
  ffffff000863bc30 zfs_ioc_pool_scrub+0x55()
  ffffff000863bcb0 zfsdev_ioctl+0x10d()
  ffffff000863bcf0 cdev_ioctl+0x48()
  ffffff000863bd30 spec_ioctl+0x86()
  ffffff000863bdb0 fop_ioctl+0x7b()
  ffffff000863bec0 ioctl+0x174()
  ffffff000863bf10 sys_syscall32+0x101()
stack pointer for thread ffffff01f9a29ba0: ffffff000829a9b0
[ ffffff000829a9b0 _resume_from_idle+0xf1() ]
  ffffff000829a9f0 swtch+0x17f()
  ffffff000829aa90 turnstile_block+0x76b()
  ffffff000829ab00 mutex_vector_enter+0x26f()
  ffffff000829ab70 spa_open_common+0x5d()
  ffffff000829abe0 spa_get_stats+0x4a()
  ffffff000829ac30 zfs_ioc_pool_stats+0x32()
  ffffff000829acb0 zfsdev_ioctl+0x10d()
  ffffff000829acf0 cdev_ioctl+0x48()
  ffffff000829ad30 spec_ioctl+0x86()
  ffffff000829adb0 fop_ioctl+0x7b()
  ffffff000829aec0 ioctl+0x174()
  ffffff000829af10 sys_syscall32+0x101()
> ::pgrep zfs | ::walk thread | ::findstack
stack pointer for thread ffffff01c7566c60: ffffff00086bd6e0
[ ffffff00086bd6e0 _resume_from_idle+0xf1() ]
  ffffff00086bd720 swtch+0x17f()
  ffffff00086bd7c0 turnstile_block+0x76b()
  ffffff00086bd830 mutex_vector_enter+0x26f()
  ffffff00086bd8a0 spa_open_common+0x5d()
  ffffff00086bd8d0 spa_open+0x1c()
  ffffff00086bda80 dsl_dir_open_spa+0x79()
  ffffff00086bdb20 dsl_dataset_open_spa+0x4b()
  ffffff00086bdb50 dsl_dataset_open+0x33()
  ffffff00086bdbc0 dmu_objset_open+0x4f()
  ffffff00086bdbf0 zfs_os_open_retry+0x2f()
  ffffff00086bdc30 zfs_ioc_objset_stats+0x24()
  ffffff00086bdcb0 zfsdev_ioctl+0x10d()
  ffffff00086bdcf0 cdev_ioctl+0x48()
  ffffff00086bdd30 spec_ioctl+0x86()
  ffffff00086bddb0 fop_ioctl+0x7b()
  ffffff00086bdec0 ioctl+0x174()
  ffffff00086bdf10 sys_syscall32+0x101()