Module Name: src
Committed By: uebayasi
Date: Wed Feb 24 15:58:26 UTC 2010
Modified Files:
src/sys/uvm: uvm_fault.c
Log Message:
Merge more indirect functions. Some comments.
To generate a diff of this commit:
cvs rdiff -u -r1.172 -r1.173 src/sys/uvm/uvm_fault.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/uvm/uvm_fault.c
diff -u src/sys/uvm/uvm_fault.c:1.172 src/sys/uvm/uvm_fault.c:1.173
--- src/sys/uvm/uvm_fault.c:1.172 Wed Feb 24 06:18:19 2010
+++ src/sys/uvm/uvm_fault.c Wed Feb 24 15:58:26 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_fault.c,v 1.172 2010/02/24 06:18:19 uebayasi Exp $ */
+/* $NetBSD: uvm_fault.c,v 1.173 2010/02/24 15:58:26 uebayasi Exp $ */
/*
*
@@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.172 2010/02/24 06:18:19 uebayasi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.173 2010/02/24 15:58:26 uebayasi Exp $");
#include "opt_uvmhist.h"
@@ -741,15 +741,12 @@
static int uvm_fault_lower(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_page **);
-static inline int uvm_fault_lower_lookup(
+static inline void uvm_fault_lower_lookup(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct vm_page **);
static inline void uvm_fault_lower_neighbor(
struct uvm_faultinfo *, struct uvm_faultctx *,
vaddr_t, struct vm_page *, bool);
-static inline int uvm_fault_lower1(
- struct uvm_faultinfo *, struct uvm_faultctx *,
- struct uvm_object *, struct vm_page *);
static inline int uvm_fault_lower_io(
struct uvm_faultinfo *, struct uvm_faultctx *,
struct uvm_object **, struct vm_page **);
@@ -827,10 +824,15 @@
struct uvm_object * const uobj = ufi.entry->object.uvm_obj;
if (uobj && uobj->pgops->pgo_fault != NULL) {
+ /*
+ * invoke "special" fault routine.
+ */
mutex_enter(&uobj->vmobjlock);
- /* locked: maps(read), amap (if there), uobj */
- error = uobj->pgops->pgo_fault(&ufi, flt.startva, pages, flt.npages,
- flt.centeridx, flt.access_type, PGO_LOCKED|PGO_SYNCIO);
+ /* locked: maps(read), amap(if there), uobj */
+ error = uobj->pgops->pgo_fault(&ufi,
+ flt.startva, pages, flt.npages,
+ flt.centeridx, flt.access_type,
+ PGO_LOCKED|PGO_SYNCIO);
/* locked: nothing, pgo_fault has unlocked everything */
@@ -850,6 +852,21 @@
return error;
}
+/*
+ * uvm_fault_check: check prot, handle needs-copy, etc.
+ *
+ * 1. lookup entry.
+ * 2. check protection.
+ * 3. adjust fault condition (mainly for simulated fault).
+ * 4. handle needs-copy (lazy amap copy).
+ * 5. establish range of interest for neighbor fault (aka pre-fault).
+ * 6. look up anons (if amap exists).
+ * 7. flush pages (if MADV_SEQUENTIAL)
+ *
+ * => called with nothing locked.
+ * => if we fail (result != 0) we unlock everything.
+ */
+
static int
uvm_fault_check(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1059,6 +1076,17 @@
return 0;
}
+/*
+ * uvm_fault_upper_lookup: look up existing h/w mapping and amap.
+ *
+ * iterate range of interest:
+ * 1. check if h/w mapping exists. if yes, we don't care
+ * 2. check if anon exists. if not, page is lower.
+ * 3. if anon exists, enter h/w mapping for neighbors.
+ *
+ * => called with amap locked (if exists).
+ */
+
static int
uvm_fault_upper_lookup(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1139,6 +1167,12 @@
return 0;
}
+/*
+ * uvm_fault_upper_neighbor: enter single lower neighbor page.
+ *
+ * => called with amap and anon locked.
+ */
+
static void
uvm_fault_upper_neighbor(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1146,6 +1180,8 @@
{
UVMHIST_FUNC("uvm_fault_upper_neighbor"); UVMHIST_CALLED(maphist);
+ /* locked: amap, anon */
+
mutex_enter(&uvm_pageqlock);
uvm_pageenqueue(pg);
mutex_exit(&uvm_pageqlock);
@@ -1169,180 +1205,14 @@
pmap_update(ufi->orig_map->pmap);
}
-static int
-uvm_fault_lower(
- struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
- struct vm_page **pages)
-{
-#ifdef DIAGNOSTIC
- struct vm_amap *amap = ufi->entry->aref.ar_amap;
-#endif
- struct uvm_object *uobj = ufi->entry->object.uvm_obj;
- struct vm_page *uobjpage;
-
- /*
- * if the desired page is not shadowed by the amap and we have a
- * backing object, then we check to see if the backing object would
- * prefer to handle the fault itself (rather than letting us do it
- * with the usual pgo_get hook). the backing object signals this by
- * providing a pgo_fault routine.
- */
-
- /*
- * now, if the desired page is not shadowed by the amap and we have
- * a backing object that does not have a special fault routine, then
- * we ask (with pgo_get) the object for resident pages that we care
- * about and attempt to map them in. we do not let pgo_get block
- * (PGO_LOCKED).
- */
-
- if (uobj == NULL) {
- /* zero fill; don't care neighbor pages */
- uobjpage = NULL;
- } else {
- uvm_fault_lower_lookup(ufi, flt, pages);
- uobjpage = pages[flt->centeridx];
- }
-
- /* locked: maps(read), amap(if there), uobj(if !null), uobjpage(if !null) */
- KASSERT(amap == NULL || mutex_owned(&amap->am_l));
- KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
- KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0);
-
- /*
- * note that at this point we are done with any front or back pages.
- * we are now going to focus on the center page (i.e. the one we've
- * faulted on). if we have faulted on the upper (anon) layer
- * [i.e. case 1], then the anon we want is anons[centeridx] (we have
- * not touched it yet). if we have faulted on the bottom (uobj)
- * layer [i.e. case 2] and the page was both present and available,
- * then we've got a pointer to it as "uobjpage" and we've already
- * made it BUSY.
- */
-
- /*
- * there are four possible cases we must address: 1A, 1B, 2A, and 2B
- */
-
- /*
- * redirect case 2: if we are not shadowed, go to case 2.
- */
-
- return uvm_fault_lower1(ufi, flt, uobj, uobjpage);
-}
-
-static int
-uvm_fault_lower_lookup(
- struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
- struct vm_page **pages)
-{
- struct uvm_object *uobj = ufi->entry->object.uvm_obj;
- int lcv, gotpages;
- vaddr_t currva;
- UVMHIST_FUNC("uvm_fault_lower_lookup"); UVMHIST_CALLED(maphist);
-
- mutex_enter(&uobj->vmobjlock);
- /* locked (!shadowed): maps(read), amap (if there), uobj */
- /*
- * the following call to pgo_get does _not_ change locking state
- */
-
- uvmexp.fltlget++;
- gotpages = flt->npages;
- (void) uobj->pgops->pgo_get(uobj,
- ufi->entry->offset + flt->startva - ufi->entry->start,
- pages, &gotpages, flt->centeridx,
- flt->access_type & MASK(ufi->entry), ufi->entry->advice, PGO_LOCKED);
-
- /*
- * check for pages to map, if we got any
- */
-
- if (gotpages == 0) {
- pages[flt->centeridx] = NULL;
- return 0;
- }
-
- currva = flt->startva;
- for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
- struct vm_page *curpg;
-
- curpg = pages[lcv];
- if (curpg == NULL || curpg == PGO_DONTCARE) {
- continue;
- }
- KASSERT(curpg->uobject == uobj);
-
- /*
- * if center page is resident and not PG_BUSY|PG_RELEASED
- * then pgo_get made it PG_BUSY for us and gave us a handle
- * to it.
- */
-
- if (lcv == flt->centeridx) {
- UVMHIST_LOG(maphist, " got uobjpage "
- "(0x%x) with locked get",
- curpg, 0,0,0);
- } else {
- bool readonly = (curpg->flags & PG_RDONLY)
- || (curpg->loan_count > 0)
- || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject);
-
- uvm_fault_lower_neighbor(ufi, flt,
- currva, curpg, readonly);
- }
- }
- pmap_update(ufi->orig_map->pmap);
- return 0;
-}
-
-static void
-uvm_fault_lower_neighbor(
- struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
- vaddr_t currva, struct vm_page *pg, bool readonly)
-{
- UVMHIST_FUNC("uvm_fault_lower_neighor"); UVMHIST_CALLED(maphist);
-
- /*
- * calling pgo_get with PGO_LOCKED returns us pages which
- * are neither busy nor released, so we don't need to check
- * for this. we can just directly enter the pages.
- */
-
- mutex_enter(&uvm_pageqlock);
- uvm_pageenqueue(pg);
- mutex_exit(&uvm_pageqlock);
- UVMHIST_LOG(maphist,
- " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x",
- ufi->orig_map->pmap, currva, pg, 0);
- uvmexp.fltnomap++;
-
- /*
- * Since this page isn't the page that's actually faulting,
- * ignore pmap_enter() failures; it's not critical that we
- * enter these right now.
- */
- KASSERT((pg->flags & PG_PAGEOUT) == 0);
- KASSERT((pg->flags & PG_RELEASED) == 0);
- KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) ||
- (pg->flags & PG_CLEAN) != 0);
-
- (void) pmap_enter(ufi->orig_map->pmap, currva,
- VM_PAGE_TO_PHYS(pg),
- readonly ? (flt->enter_prot & ~VM_PROT_WRITE) :
- flt->enter_prot & MASK(ufi->entry),
- PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0));
-
- /*
- * NOTE: page can't be PG_WANTED or PG_RELEASED because we've
- * held the lock the whole time we've had the handle.
- */
- KASSERT((pg->flags & PG_WANTED) == 0);
- KASSERT((pg->flags & PG_RELEASED) == 0);
-
- pg->flags &= ~(PG_BUSY);
- UVM_PAGE_OWN(pg, NULL);
-}
+/*
+ * uvm_fault_upper: handle upper fault.
+ *
+ * 1. acquire anon lock.
+ * 2. get anon. let uvmfault_anonget do the dirty work.
+ * 3. handle loan.
+ * 4. dispatch direct or promote handlers.
+ */
static int
uvm_fault_upper(
@@ -1442,6 +1312,13 @@
return error;
}
+/*
+ * uvm_fault_upper_loan: handle loaned upper page.
+ *
+ * 1. if not cow'ing now, just mark enter_prot as read-only.
+ * 2. if cow'ing now, and if ref count is 1, break loan.
+ */
+
static int
uvm_fault_upper_loan(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1449,6 +1326,7 @@
{
struct vm_amap * const amap = ufi->entry->aref.ar_amap;
int error = 0;
+ UVMHIST_FUNC("uvm_fault_upper_loan"); UVMHIST_CALLED(maphist);
if (!flt->cow_now) {
@@ -1489,6 +1367,15 @@
return error;
}
+/*
+ * uvm_fault_upper_promote: promote upper page.
+ *
+ * 1. call uvmfault_promote.
+ * 2. enqueue page.
+ * 3. deref.
+ * 4. pass page to uvm_fault_upper_enter.
+ */
+
static int
uvm_fault_upper_promote(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1532,6 +1419,10 @@
return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon);
}
+/*
+ * uvm_fault_upper_direct: handle direct fault.
+ */
+
static int
uvm_fault_upper_direct(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1539,6 +1430,7 @@
{
struct vm_anon * const oanon = anon;
struct vm_page *pg;
+ UVMHIST_FUNC("uvm_fault_upper_direct"); UVMHIST_CALLED(maphist);
uvmexp.flt_anon++;
pg = anon->an_page;
@@ -1548,6 +1440,10 @@
return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon);
}
+/*
+ * uvm_fault_upper_enter: enter h/w mapping of upper page.
+ */
+
static int
uvm_fault_upper_enter(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1557,7 +1453,7 @@
struct vm_amap * const amap = ufi->entry->aref.ar_amap;
UVMHIST_FUNC("uvm_fault_upper_enter"); UVMHIST_CALLED(maphist);
- /* locked: maps(read), amap, oanon, anon (if different from oanon) */
+ /* locked: maps(read), amap, oanon, anon(if different from oanon) */
KASSERT(mutex_owned(&amap->am_l));
KASSERT(mutex_owned(&anon->an_lock));
KASSERT(mutex_owned(&oanon->an_lock));
@@ -1607,11 +1503,16 @@
return 0;
}
+/*
+ * uvm_fault_upper_done: queue upper center page.
+ */
+
static void
uvm_fault_upper_done(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct uvm_object *uobj, struct vm_anon *anon, struct vm_page *pg)
{
+ UVMHIST_FUNC("uvm_fault_upper_done"); UVMHIST_CALLED(maphist);
/*
* ... update the page queues.
@@ -1636,19 +1537,64 @@
mutex_exit(&uvm_pageqlock);
}
+/*
+ * uvm_fault_lower: handle lower fault.
+ *
+ * 1. check uobj
+ * 1.1. if null, ZFOD.
+ * 1.2. if not null, look up unnmapped neighbor pages.
+ * 2. for center page, check if promote.
+ * 2.1. ZFOD always needs promotion.
+ * 2.2. other uobjs, when entry is marked COW (usually MAP_PRIVATE vnode).
+ * 3. if uobj is not ZFOD and page is not found, do i/o.
+ * 4. dispatch either direct / promote fault.
+ */
+
static int
-uvm_fault_lower1(
+uvm_fault_lower(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
- struct uvm_object *uobj, struct vm_page *uobjpage)
+ struct vm_page **pages)
{
#ifdef DIAGNOSTIC
- struct vm_amap * const amap = ufi->entry->aref.ar_amap;
+ struct vm_amap *amap = ufi->entry->aref.ar_amap;
#endif
+ struct uvm_object *uobj = ufi->entry->object.uvm_obj;
+ struct vm_page *uobjpage;
int error;
- UVMHIST_FUNC("uvm_fault_lower1"); UVMHIST_CALLED(maphist);
+ UVMHIST_FUNC("uvm_fault_lower"); UVMHIST_CALLED(maphist);
+
+ /* locked: maps(read), amap(if there), uobj(if !null) */
/*
- * handle case 2: faulting on backing object or zero fill
+ * now, if the desired page is not shadowed by the amap and we have
+ * a backing object that does not have a special fault routine, then
+ * we ask (with pgo_get) the object for resident pages that we care
+ * about and attempt to map them in. we do not let pgo_get block
+ * (PGO_LOCKED).
+ */
+
+ if (uobj == NULL) {
+ /* zero fill; don't care neighbor pages */
+ uobjpage = NULL;
+ } else {
+ uvm_fault_lower_lookup(ufi, flt, pages);
+ uobjpage = pages[flt->centeridx];
+ }
+
+ /* locked: maps(read), amap(if there), uobj(if !null), uobjpage(if !null) */
+ KASSERT(amap == NULL || mutex_owned(&amap->am_l));
+ KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
+ KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0);
+
+ /*
+ * note that at this point we are done with any front or back pages.
+ * we are now going to focus on the center page (i.e. the one we've
+ * faulted on). if we have faulted on the upper (anon) layer
+ * [i.e. case 1], then the anon we want is anons[centeridx] (we have
+ * not touched it yet). if we have faulted on the bottom (uobj)
+ * layer [i.e. case 2] and the page was both present and available,
+ * then we've got a pointer to it as "uobjpage" and we've already
+ * made it BUSY.
*/
/*
@@ -1722,6 +1668,136 @@
return error;
}
+/*
+ * uvm_fault_lower_lookup: look up on-memory uobj pages.
+ *
+ * 1. get on-memory pages.
+ * 2. if failed, give up (get only center page later).
+ * 3. if succeeded, enter h/w mapping of neighbor pages.
+ */
+
+static void
+uvm_fault_lower_lookup(
+ struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
+ struct vm_page **pages)
+{
+ struct uvm_object *uobj = ufi->entry->object.uvm_obj;
+ int lcv, gotpages;
+ vaddr_t currva;
+ UVMHIST_FUNC("uvm_fault_lower_lookup"); UVMHIST_CALLED(maphist);
+
+ mutex_enter(&uobj->vmobjlock);
+ /* locked: maps(read), amap(if there), uobj */
+ /*
+ * the following call to pgo_get does _not_ change locking state
+ */
+
+ uvmexp.fltlget++;
+ gotpages = flt->npages;
+ (void) uobj->pgops->pgo_get(uobj,
+ ufi->entry->offset + flt->startva - ufi->entry->start,
+ pages, &gotpages, flt->centeridx,
+ flt->access_type & MASK(ufi->entry), ufi->entry->advice, PGO_LOCKED);
+
+ /*
+ * check for pages to map, if we got any
+ */
+
+ if (gotpages == 0) {
+ pages[flt->centeridx] = NULL;
+ return;
+ }
+
+ currva = flt->startva;
+ for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
+ struct vm_page *curpg;
+
+ curpg = pages[lcv];
+ if (curpg == NULL || curpg == PGO_DONTCARE) {
+ continue;
+ }
+ KASSERT(curpg->uobject == uobj);
+
+ /*
+ * if center page is resident and not PG_BUSY|PG_RELEASED
+ * then pgo_get made it PG_BUSY for us and gave us a handle
+ * to it.
+ */
+
+ if (lcv == flt->centeridx) {
+ UVMHIST_LOG(maphist, " got uobjpage "
+ "(0x%x) with locked get",
+ curpg, 0,0,0);
+ } else {
+ bool readonly = (curpg->flags & PG_RDONLY)
+ || (curpg->loan_count > 0)
+ || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject);
+
+ uvm_fault_lower_neighbor(ufi, flt,
+ currva, curpg, readonly);
+ }
+ }
+ pmap_update(ufi->orig_map->pmap);
+}
+
+/*
+ * uvm_fault_lower_neighbor: enter h/w mapping of lower neighbor page.
+ */
+
+static void
+uvm_fault_lower_neighbor(
+ struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
+ vaddr_t currva, struct vm_page *pg, bool readonly)
+{
+ UVMHIST_FUNC("uvm_fault_lower_neighor"); UVMHIST_CALLED(maphist);
+
+ /* locked: maps(read), amap(if there), uobj */
+
+ /*
+ * calling pgo_get with PGO_LOCKED returns us pages which
+ * are neither busy nor released, so we don't need to check
+ * for this. we can just directly enter the pages.
+ */
+
+ mutex_enter(&uvm_pageqlock);
+ uvm_pageenqueue(pg);
+ mutex_exit(&uvm_pageqlock);
+ UVMHIST_LOG(maphist,
+ " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x",
+ ufi->orig_map->pmap, currva, pg, 0);
+ uvmexp.fltnomap++;
+
+ /*
+ * Since this page isn't the page that's actually faulting,
+ * ignore pmap_enter() failures; it's not critical that we
+ * enter these right now.
+ * NOTE: page can't be PG_WANTED or PG_RELEASED because we've
+ * held the lock the whole time we've had the handle.
+ */
+ KASSERT((pg->flags & PG_PAGEOUT) == 0);
+ KASSERT((pg->flags & PG_RELEASED) == 0);
+ KASSERT((pg->flags & PG_WANTED) == 0);
+ KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) ||
+ (pg->flags & PG_CLEAN) != 0);
+ pg->flags &= ~(PG_BUSY);
+ UVM_PAGE_OWN(pg, NULL);
+
+ (void) pmap_enter(ufi->orig_map->pmap, currva,
+ VM_PAGE_TO_PHYS(pg),
+ readonly ? (flt->enter_prot & ~VM_PROT_WRITE) :
+ flt->enter_prot & MASK(ufi->entry),
+ PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0));
+}
+
+/*
+ * uvm_fault_lower_io: get lower page from backing store.
+ *
+ * 1. unlock everything, because i/o will block.
+ * 2. call pgo_get.
+ * 3. if failed, recover.
+ * 4. if succeeded, relock everything and verify things.
+ */
+
static int
uvm_fault_lower_io(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1852,12 +1928,20 @@
return 0;
}
+/*
+ * uvm_fault_lower_direct: fault lower center page
+ *
+ * 1. adjust h/w mapping protection.
+ * 2. if page is loaned, resolve.
+ */
+
int
uvm_fault_lower_direct(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
struct uvm_object *uobj, struct vm_page *uobjpage)
{
struct vm_page *pg;
+ UVMHIST_FUNC("uvm_fault_lower_direct"); UVMHIST_CALLED(maphist);
/*
* we are not promoting. if the mapping is COW ensure that we
@@ -1889,6 +1973,13 @@
return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg, uobjpage);
}
+/*
+ * uvm_fault_lower_direct_loan: resolve loaned page.
+ *
+ * 1. if not cow'ing, adjust h/w mapping protection.
+ * 2. if cow'ing, break loan.
+ */
+
static int
uvm_fault_lower_direct_loan(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -1932,6 +2023,14 @@
return 0;
}
+/*
+ * uvm_fault_lower_promote: promote lower page.
+ *
+ * 1. call uvmfault_promote.
+ * 2. fill in data.
+ * 3. if not ZFOD, dispose old page.
+ */
+
int
uvm_fault_lower_promote(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -2016,6 +2115,10 @@
return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg, uobjpage);
}
+/*
+ * uvm_fault_lower_enter: enter h/w mapping of lower page.
+ */
+
int
uvm_fault_lower_enter(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
@@ -2094,6 +2197,10 @@
return 0;
}
+/*
+ * uvm_fault_lower_done: queue lower center page.
+ */
+
void
uvm_fault_lower_done(
struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
