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fix released pg bugs detected by Chuck S.: 

- release the correct page (ppsp[lcv], not pg)
 - don't access the page's fields after we have released it
 - in the uvm_objct case: move on to the next page if we've released
[should have been merged in on 1998/02/12, but we somehow missed it]
This commit is contained in:
chuck 1998-03-22 16:10:29 +00:00
parent 528890f3ab
commit 617118bccc
1 changed files with 15 additions and 4 deletions
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19
sys/uvm/uvm_pager.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: uvm_pager.c,v 1.6 1998/03/09 00:58:58 mrg Exp $ */
/* $NetBSD: uvm_pager.c,v 1.7 1998/03/22 16:10:29 chuck Exp $ */
/*
* XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
@ -605,6 +605,7 @@ int swblk; /* valid if (uobj == NULL && PGO_REALLOCSWAP) */
{
int lcv;
boolean_t obj_is_alive;
struct uvm_object *saved_uobj;
/*
* if we need to reallocate swap space for the cluster we are dropping
@ -684,8 +685,9 @@ int swblk; /* valid if (uobj == NULL && PGO_REALLOCSWAP) */
panic("uvm_pager_dropcluster: no releasepg "
"function");
#endif
saved_uobj = ppsp[lcv]->uobject;
obj_is_alive =
ppsp[lcv]->uobject->pgops->pgo_releasepg(pg, NULL);
saved_uobj->pgops->pgo_releasepg(ppsp[lcv], NULL);
#ifdef DIAGNOSTIC
/* for normal objects, "pg" is still PG_BUSY by us,
@ -694,8 +696,17 @@ int swblk; /* valid if (uobj == NULL && PGO_REALLOCSWAP) */
panic("uvm_pager_dropcluster: object died "
"with active page");
#endif
if (!obj_is_alive)
continue;
/* only unlock the object if it is still alive... */
if (obj_is_alive && saved_uobj != uobj)
simple_unlock(&saved_uobj->vmobjlock);
/*
* XXXCDC: suppose uobj died in the pgo_releasepg?
* how pass that
* info up to caller. we are currently ignoring it...
*/
continue; /* next page */
} else {
ppsp[lcv]->flags &= ~(PG_BUSY|PG_WANTED);