Author: kib
Date: Wed Jun 1 20:39:00 2016
New Revision: 301165
URL: https://svnweb.freebsd.org/changeset/base/301165
Log:
If the fast path unbusy in vm_page_replace() fails, slow path needs to
acquire the page lock, which recurses. Avoid the recursion by reusing
the code from vm_page_remove() in a new helper
vm_page_xunbusy_maybelocked().
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/vm/vm_page.c
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Wed Jun 1 20:30:31 2016 (r301164)
+++ head/sys/vm/vm_page.c Wed Jun 1 20:39:00 2016 (r301165)
@@ -759,6 +759,22 @@ vm_page_trysbusy(vm_page_t m)
}
}
+static void
+vm_page_xunbusy_maybelocked(vm_page_t m)
+{
+ bool lockacq;
+
+ vm_page_assert_xbusied(m);
+
+ lockacq = !mtx_owned(vm_page_lockptr(m));
+ if (lockacq)
+ vm_page_lock(m);
+ vm_page_flash(m);
+ atomic_store_rel_int(&m->busy_lock, VPB_UNBUSIED);
+ if (lockacq)
+ vm_page_unlock(m);
+}
+
/*
* vm_page_xunbusy_hard:
*
@@ -1197,25 +1213,14 @@ void
vm_page_remove(vm_page_t m)
{
vm_object_t object;
- boolean_t lockacq;
if ((m->oflags & VPO_UNMANAGED) == 0)
- vm_page_lock_assert(m, MA_OWNED);
+ vm_page_assert_locked(m);
if ((object = m->object) == NULL)
return;
VM_OBJECT_ASSERT_WLOCKED(object);
- if (vm_page_xbusied(m)) {
- lockacq = FALSE;
- if ((m->oflags & VPO_UNMANAGED) != 0 &&
- !mtx_owned(vm_page_lockptr(m))) {
- lockacq = TRUE;
- vm_page_lock(m);
- }
- vm_page_flash(m);
- atomic_store_rel_int(&m->busy_lock, VPB_UNBUSIED);
- if (lockacq)
- vm_page_unlock(m);
- }
+ if (vm_page_xbusied(m))
+ vm_page_xunbusy_maybelocked(m);
/*
* Now remove from the object's list of backed pages.
@@ -1340,7 +1345,7 @@ vm_page_replace(vm_page_t mnew, vm_objec
TAILQ_REMOVE(&object->memq, mold, listq);
mold->object = NULL;
- vm_page_xunbusy(mold);
+ vm_page_xunbusy_maybelocked(mold);
/*
* The object's resident_page_count does not change because we have
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
