[src/trunk]: src/sys/uvm - ensure that the promoted page is on the queue even...

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/63736997739a
branches:  trunk
changeset: 763958:63736997739a
user:      yamt <yamt%NetBSD.org@localhost>
date:      Fri Apr 08 10:42:51 2011 +0000

description:
- ensure that the promoted page is on the queue even when later pmap_enter
 failed.
- don't activate a page twice.
- remove an argument which is used only for an assertion.
- assertions and comments.

diffstat:

 sys/uvm/uvm_fault.c |  37 +++++++++++++++++++++++++------------
 1 files changed, 25 insertions(+), 12 deletions(-)

diffs (127 lines):

diff -r 39916f74dd7a -r 63736997739a sys/uvm/uvm_fault.c
--- a/sys/uvm/uvm_fault.c       Fri Apr 08 10:36:58 2011 +0000
+++ b/sys/uvm/uvm_fault.c       Fri Apr 08 10:42:51 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_fault.c,v 1.182 2011/02/10 21:05:52 skrll Exp $    */
+/*     $NetBSD: uvm_fault.c,v 1.183 2011/04/08 10:42:51 yamt Exp $     */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.182 2011/02/10 21:05:52 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.183 2011/04/08 10:42:51 yamt Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -536,6 +536,8 @@
  * => if we fail (result != 0) we unlock everything.
  * => on success, return a new locked anon via 'nanon'.
  *    (*nanon)->an_page will be a resident, locked, dirty page.
+ * => it's caller's responsibility to put the promoted nanon->an_page to the
+ *    page queue.
  */
 
 static int
@@ -756,8 +758,7 @@
 static int             uvm_fault_lower_enter(
                            struct uvm_faultinfo *, const struct uvm_faultctx *,
                            struct uvm_object *,
-                           struct vm_anon *, struct vm_page *,
-                           struct vm_page *);
+                           struct vm_anon *, struct vm_page *);
 static inline void     uvm_fault_lower_done(
                            struct uvm_faultinfo *, const struct uvm_faultctx *,
                            struct uvm_object *, struct vm_page *);
@@ -797,7 +798,7 @@
        ufi.orig_size = PAGE_SIZE;      /* can't get any smaller than this */
 
        error = ERESTART;
-       while (error == ERESTART) {
+       while (error == ERESTART) { /* ReFault: */
                anons = anons_store;
                pages = pages_store;
 
@@ -1402,12 +1403,13 @@
 
        pg = anon->an_page;
        mutex_enter(&uvm_pageqlock);
-       uvm_pageactivate(pg);
+       uvm_pageenqueue(pg); /* uvm_fault_upper_done will activate the page */
        mutex_exit(&uvm_pageqlock);
        pg->flags &= ~(PG_BUSY|PG_FAKE);
        UVM_PAGE_OWN(pg, NULL);
 
        /* deref: can not drop to zero here by defn! */
+       KASSERT(oanon->an_ref > 1);
        oanon->an_ref--;
 
        /*
@@ -1975,7 +1977,8 @@
        }
        KASSERT(pg == uobjpage);
 
-       return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg, uobjpage);
+       KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0);
+       return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg);
 }
 
 /*
@@ -2118,18 +2121,20 @@
                    anon, pg, 0, 0);
        }
 
-       return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg, uobjpage);
+       KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0);
+       return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg);
 }
 
 /*
- * uvm_fault_lower_enter: enter h/w mapping of lower page.
+ * uvm_fault_lower_enter: enter h/w mapping of lower page or anon page promoted
+ * from the lower page.
  */
 
 int
 uvm_fault_lower_enter(
        struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt,
        struct uvm_object *uobj,
-       struct vm_anon *anon, struct vm_page *pg, struct vm_page *uobjpage)
+       struct vm_anon *anon, struct vm_page *pg)
 {
        struct vm_amap * const amap = ufi->entry->aref.ar_amap;
        int error;
@@ -2137,14 +2142,13 @@
 
        /*
         * locked:
-        * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj),
+        * maps(read), amap(if !null), uobj(if !null),
         *   anon(if !null), pg(if anon)
         *
         * note: pg is either the uobjpage or the new page in the new anon
         */
        KASSERT(amap == NULL || mutex_owned(&amap->am_l));
        KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
-       KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0);
        KASSERT(anon == NULL || mutex_owned(&anon->an_lock));
        KASSERT((pg->flags & PG_BUSY) != 0);
 
@@ -2173,6 +2177,15 @@
                 * as the map may change while we're asleep.
                 */
 
+               /*
+                * ensure that the page is queued in the case that
+                * we just promoted the page.
+                */
+
+               mutex_enter(&uvm_pageqlock);
+               uvm_pageenqueue(pg);
+               mutex_exit(&uvm_pageqlock);
+
                if (pg->flags & PG_WANTED)
                        wakeup(pg);