diff options
| -rw-r--r-- | sys/vm/vm_page.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c index 433c875..f166649 100644 --- a/sys/vm/vm_page.c +++ b/sys/vm/vm_page.c @@ -515,15 +515,26 @@ void vm_page_busy_downgrade(vm_page_t m) { u_int x; + bool locked; vm_page_assert_xbusied(m); + locked = mtx_owned(vm_page_lockptr(m)); for (;;) { x = m->busy_lock; x &= VPB_BIT_WAITERS; + if (x != 0 && !locked) + vm_page_lock(m); if (atomic_cmpset_rel_int(&m->busy_lock, - VPB_SINGLE_EXCLUSIVER | x, VPB_SHARERS_WORD(1) | x)) + VPB_SINGLE_EXCLUSIVER | x, VPB_SHARERS_WORD(1))) break; + if (x != 0 && !locked) + vm_page_unlock(m); + } + if (x != 0) { + wakeup(m); + if (!locked) + vm_page_unlock(m); } } |
