OS-7753 THREAD_KPRI_RELEASE does nothing of the sort
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>

*** 18,27 ****
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2019 Joyent, Inc.
   */
  
  
  /*
   * VM - page locking primitives
*** 362,372 ****
                           * writer that wants exclusive access, return failure
                           */
                          retval = 0;
                  } else if ((pp->p_selock & ~SE_EWANTED) == 0) {
                          /* no reader/writer lock held */
-                         THREAD_KPRI_REQUEST();
                          /* this clears our setting of the SE_EWANTED bit */
                          pp->p_selock = SE_WRITER;
                          retval = 1;
                  } else {
                          /* page is locked */
--- 363,372 ----
*** 549,559 ****
           * SE_EXCL_WANTED.
           */
          if (!(old & SE_EWANTED) || (es & SE_EXCL_WANTED)) {
                  if ((old & ~SE_EWANTED) == 0) {
                          /* no reader/writer lock held */
-                         THREAD_KPRI_REQUEST();
                          /* this clears out our setting of the SE_EWANTED bit */
                          pp->p_selock = SE_WRITER;
                          mutex_exit(pse);
                          return (1);
                  }
--- 549,558 ----
*** 588,598 ****
                  return (0);
          }
  
          if (se == SE_EXCL) {
                  if (pp->p_selock == 0) {
-                         THREAD_KPRI_REQUEST();
                          pp->p_selock = SE_WRITER;
                          mutex_exit(pse);
                          return (1);
                  }
          } else {
--- 587,596 ----
*** 626,636 ****
                  if (CV_HAS_WAITERS(&pp->p_cv))
                          cv_broadcast(&pp->p_cv);
          } else if ((old & ~SE_EWANTED) == SE_DELETED) {
                  panic("page_unlock_nocapture: page %p is deleted", (void *)pp);
          } else if (old < 0) {
-                 THREAD_KPRI_RELEASE();
                  pp->p_selock &= SE_EWANTED;
                  if (CV_HAS_WAITERS(&pp->p_cv))
                          cv_broadcast(&pp->p_cv);
          } else if ((old & ~SE_EWANTED) > SE_READER) {
                  pp->p_selock = old - SE_READER;
--- 624,633 ----
*** 660,670 ****
                  if (CV_HAS_WAITERS(&pp->p_cv))
                          cv_broadcast(&pp->p_cv);
          } else if ((old & ~SE_EWANTED) == SE_DELETED) {
                  panic("page_unlock: page %p is deleted", (void *)pp);
          } else if (old < 0) {
-                 THREAD_KPRI_RELEASE();
                  pp->p_selock &= SE_EWANTED;
                  if (CV_HAS_WAITERS(&pp->p_cv))
                          cv_broadcast(&pp->p_cv);
          } else if ((old & ~SE_EWANTED) > SE_READER) {
                  pp->p_selock = old - SE_READER;
--- 657,666 ----
*** 680,690 ****
                   * relatively long time in the kernel making no progress.
                   */
                  if ((pp->p_toxic & PR_CAPTURE) &&
                      !(curthread->t_flag & T_CAPTURING) &&
                      !PP_RETIRED(pp)) {
-                         THREAD_KPRI_REQUEST();
                          pp->p_selock = SE_WRITER;
                          mutex_exit(pse);
                          page_unlock_capture(pp);
                  } else {
                          mutex_exit(pse);
--- 676,685 ----
*** 710,720 ****
  
          mutex_enter(pse);
          if (!(pp->p_selock & SE_EWANTED)) {
                  /* no threads want exclusive access, try upgrade */
                  if (pp->p_selock == SE_READER) {
-                         THREAD_KPRI_REQUEST();
                          /* convert to exclusive lock */
                          pp->p_selock = SE_WRITER;
                          mutex_exit(pse);
                          return (1);
                  }
--- 705,714 ----
*** 736,746 ****
          ASSERT((pp->p_selock & ~SE_EWANTED) != SE_DELETED);
          ASSERT(PAGE_EXCL(pp));
  
          mutex_enter(pse);
          excl_waiting =  pp->p_selock & SE_EWANTED;
-         THREAD_KPRI_RELEASE();
          pp->p_selock = SE_READER | excl_waiting;
          if (CV_HAS_WAITERS(&pp->p_cv))
                  cv_broadcast(&pp->p_cv);
          mutex_exit(pse);
  }
--- 730,739 ----
*** 754,764 ****
          ASSERT(pp->p_vnode == NULL);
          ASSERT(pp->p_offset == (u_offset_t)-1);
          ASSERT(!PP_ISFREE(pp));
  
          mutex_enter(pse);
-         THREAD_KPRI_RELEASE();
          pp->p_selock = SE_DELETED;
          if (CV_HAS_WAITERS(&pp->p_cv))
                  cv_broadcast(&pp->p_cv);
          mutex_exit(pse);
  }
--- 747,756 ----