illumos gate

seen on SmartOS joyent_20150917T232817Z

zfs create -ps -V 1t z4/t/pool-1a
zfs create -ps -V 1t z4/t/pool-1b
zpool create pool-1a /dev/zvol/dsk/z4/t/pool-1a
zpool create pool-1b /dev/zvol/dsk/z4/t/pool-1b

zfs create -p pool-1a/prod/a/test
zfs create -p pool-1b/repl
zfs snapshot -r pool-1a/prod/a@repl-1
zfs send -R pool-1a/prod/a@repl-1 | zfs recv -Fdu pool-1b/repl

> 0t44894::pid2proc|::ps -ft
S    PID   PPID   PGID    SID    UID      FLAGS             ADDR NAME
R  44894  44828  44894  44828      0 0x4a004000 ffffff2ef067a010 zfs send -R pool-1a/prod/a@repl-1
        T  0xffffff2dd90d8040 <TS_SLEEP>
> 0xffffff2dd90d8040::findstack
stack pointer for thread ffffff2dd90d8040: ffffff00b9e687a0
[ ffffff00b9e687a0 _resume_from_idle+0xf4() ]
  ffffff00b9e687d0 swtch+0x141()
  ffffff00b9e68810 cv_wait+0x70()
  ffffff00b9e68860 txg_wait_synced+0x83()
  ffffff00b9e68970 dsl_sync_task+0x1a5()
  ffffff00b9e68b20 dsl_dataset_user_release_impl+0x1df()
  ffffff00b9e68b40 dsl_dataset_user_release_tmp+0x1d()
  ffffff00b9e68b80 dsl_dataset_user_release_onexit+0x8b()
  ffffff00b9e68bc0 zfs_onexit_destroy+0x43()
  ffffff00b9e68bf0 zfs_ctldev_destroy+0x18()
  ffffff00b9e68c50 zfsdev_close+0x89()
  ffffff00b9e68c80 dev_close+0x31()
  ffffff00b9e68cd0 device_close+0xd8()
  ffffff00b9e68d60 spec_close+0x17b()
  ffffff00b9e68de0 fop_close+0x61()
  ffffff00b9e68e20 closef+0x5e()
  ffffff00b9e68e90 closeandsetf+0x398()
  ffffff00b9e68eb0 close+0x13()
  ffffff00b9e68f10 _sys_sysenter_post_swapgs+0x153()

> 0t44895::pid2proc|::ps -ft
S    PID   PPID   PGID    SID    UID      FLAGS             ADDR NAME
R  44895  44828  44894  44828      0 0x4a004000 ffffff2ef33b4080 zfs recv -Fdu pool-1b/repl
        T  0xffffff19d26bc800 <TS_SLEEP>
> 0xffffff19d26bc800::findstack
stack pointer for thread ffffff19d26bc800: ffffff00bb8b8790
[ ffffff00bb8b8790 _resume_from_idle+0xf4() ]
  ffffff00bb8b87c0 swtch+0x141()
  ffffff00bb8b8800 cv_wait+0x70()
  ffffff00bb8b8850 txg_wait_synced+0x83()
  ffffff00bb8b8960 dsl_sync_task+0x1a5()
  ffffff00bb8b8990 dmu_recv_new_end+0x3a()
  ffffff00bb8b89b0 dmu_recv_end+0x2d()
  ffffff00bb8b8bc0 zfs_ioc_recv+0x549()
  ffffff00bb8b8c70 zfsdev_ioctl+0x4a7()
  ffffff00bb8b8cb0 cdev_ioctl+0x39()
  ffffff00bb8b8d00 spec_ioctl+0x60()
  ffffff00bb8b8d90 fop_ioctl+0x55()
  ffffff00bb8b8eb0 ioctl+0x9b()
  ffffff00bb8b8f10 _sys_sysenter_post_swapgs+0x153()