[src/trunk]: src/sys/arch Fix another locking error: if freeing a PV entry, d...

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

details:   https://anonhg.NetBSD.org/src/rev/d38d3bc604f3
branches:  trunk
changeset: 474979:d38d3bc604f3
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Wed Jul 28 06:54:41 1999 +0000

description:
Fix another locking error: if freeing a PV entry, don't attempt to
free a PV page if the PV entry was associated with the kernel pmap,
since the kernel pmap is locked, and freeing the page will execute
a code path which will attempt to lock it again, resulting in deadlock.
No real loss, since the next time a PV entry is freed, the page will
be freed, too.

diffstat:

 sys/arch/i386/i386/pmap.c   |  34 +++++++++++++++++++++++-----------
 sys/arch/pc532/pc532/pmap.c |  34 +++++++++++++++++++++++-----------
 2 files changed, 46 insertions(+), 22 deletions(-)

diffs (204 lines):

diff -r 6b19dc5f313e -r d38d3bc604f3 sys/arch/i386/i386/pmap.c
--- a/sys/arch/i386/i386/pmap.c Wed Jul 28 06:35:15 1999 +0000
+++ b/sys/arch/i386/i386/pmap.c Wed Jul 28 06:54:41 1999 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.77 1999/07/28 05:37:54 thorpej Exp $        */
+/*     $NetBSD: pmap.c,v 1.78 1999/07/28 06:54:41 thorpej Exp $        */
 
 /*
  *
@@ -400,8 +400,8 @@
 static void             pmap_enter_pv __P((struct pv_head *,
                                            struct pv_entry *, struct pmap *,
                                            vaddr_t, struct vm_page *));
-static void             pmap_free_pv __P((struct pv_entry *));
-static void             pmap_free_pvs __P((struct pv_entry *));
+static void             pmap_free_pv __P((struct pmap *, struct pv_entry *));
+static void             pmap_free_pvs __P((struct pmap *, struct pv_entry *));
 static void             pmap_free_pv_doit __P((struct pv_entry *));
 static void             pmap_free_pvpage __P((void));
 static struct vm_page  *pmap_get_ptp __P((struct pmap *, int, boolean_t));
@@ -1416,13 +1416,19 @@
  */
 
 __inline static void
-pmap_free_pv(pv)
+pmap_free_pv(pmap, pv)
+       struct pmap *pmap;
        struct pv_entry *pv;
 {
        simple_lock(&pvalloc_lock);
        pmap_free_pv_doit(pv);
 
-       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL)
+       /*
+        * Can't free the PV page if the PV entries were associated with
+        * the kernel pmap; the pmap is already locked.
+        */
+       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL &&
+           pmap != pmap_kernel())
                pmap_free_pvpage();
 
        simple_unlock(&pvalloc_lock);
@@ -1435,7 +1441,8 @@
  */
 
 __inline static void
-pmap_free_pvs(pvs)
+pmap_free_pvs(pmap, pvs)
+       struct pmap *pmap;
        struct pv_entry *pvs;
 {
        struct pv_entry *nextpv;
@@ -1447,7 +1454,12 @@
                pmap_free_pv_doit(pvs);
        }
 
-       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL)
+       /*
+        * Can't free the PV page if the PV entries were associated with
+        * the kernel pmap; the pmap is already locked.
+        */
+       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL &&
+           pmap != pmap_kernel())
                pmap_free_pvpage();
 
        simple_unlock(&pvalloc_lock);
@@ -2246,7 +2258,7 @@
                /* end of "for" loop: time for next pte */
        }
        if (pv_tofree)
-               pmap_free_pvs(pv_tofree);
+               pmap_free_pvs(pmap, pv_tofree);
 }
 
 
@@ -2311,7 +2323,7 @@
        simple_unlock(&vm_physmem[bank].pmseg.pvhead[off].pvh_lock);
 
        if (pve)
-               pmap_free_pv(pve);
+               pmap_free_pv(pmap, pve);
        return(TRUE);
 }
 
@@ -2605,7 +2617,7 @@
                }
                pmap_unmap_ptes(pve->pv_pmap);          /* unlocks pmap */
        }
-       pmap_free_pvs(pvh->pvh_list);
+       pmap_free_pvs(NULL, pvh->pvh_list);
        pvh->pvh_list = NULL;
        simple_unlock(&pvh->pvh_lock);
        PMAP_HEAD_TO_MAP_UNLOCK();
@@ -3557,7 +3569,7 @@
                /* new mapping is not PG_PVLIST.   free pve if we've got one */
                pvh = NULL;             /* ensure !PG_PVLIST */
                if (pve)
-                       pmap_free_pv(pve);
+                       pmap_free_pv(pmap, pve);
        }
 
 enter_now:
diff -r 6b19dc5f313e -r d38d3bc604f3 sys/arch/pc532/pc532/pmap.c
--- a/sys/arch/pc532/pc532/pmap.c       Wed Jul 28 06:35:15 1999 +0000
+++ b/sys/arch/pc532/pc532/pmap.c       Wed Jul 28 06:54:41 1999 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.43 1999/07/28 05:37:55 thorpej Exp $        */
+/*     $NetBSD: pmap.c,v 1.44 1999/07/28 06:54:42 thorpej Exp $        */
 
 /*
  *
@@ -374,8 +374,8 @@
 static void             pmap_enter_pv __P((struct pv_head *,
                                            struct pv_entry *, struct pmap *,
                                            vaddr_t, struct vm_page *));
-static void             pmap_free_pv __P((struct pv_entry *));
-static void             pmap_free_pvs __P((struct pv_entry *));
+static void             pmap_free_pv __P((struct pmap *, struct pv_entry *));
+static void             pmap_free_pvs __P((struct pmap *, struct pv_entry *));
 static void             pmap_free_pv_doit __P((struct pv_entry *));
 static void             pmap_free_pvpage __P((void));
 static struct vm_page  *pmap_get_ptp __P((struct pmap *, int, boolean_t));
@@ -1324,13 +1324,19 @@
  */
 
 __inline static void
-pmap_free_pv(pv)
+pmap_free_pv(pmap, pv)
+       struct pmap *pmap;
        struct pv_entry *pv;
 {
        simple_lock(&pvalloc_lock);
        pmap_free_pv_doit(pv);
 
-       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL)
+       /*
+        * Can't free the PV page if the PV entries were associated with
+        * the kernel pmap; the pmap is already locked.
+        */
+       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL &&
+           pmap != pmap_kernel())
                pmap_free_pvpage();
 
        simple_unlock(&pvalloc_lock);
@@ -1343,7 +1349,8 @@
  */
 
 __inline static void
-pmap_free_pvs(pvs)
+pmap_free_pvs(pmap, pvs)
+       struct pmap *pmap;
        struct pv_entry *pvs;
 {
        struct pv_entry *nextpv;
@@ -1355,7 +1362,12 @@
                pmap_free_pv_doit(pvs);
        }
 
-       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL)
+       /*
+        * Can't free the PV page if the PV entries were associated with
+        * the kernel pmap; the pmap is already locked.
+        */
+       if (pv_nfpvents > PVE_HIWAT && pv_unusedpgs.tqh_first != NULL &&
+           pmap != pmap_kernel())
                pmap_free_pvpage();
 
        simple_unlock(&pvalloc_lock);
@@ -2061,7 +2073,7 @@
                /* end of "for" loop: time for next pte */
        }
        if (pv_tofree)
-               pmap_free_pvs(pv_tofree);
+               pmap_free_pvs(pmap, pv_tofree);
 }
 
 
@@ -2126,7 +2138,7 @@
        simple_unlock(&vm_physmem[bank].pmseg.pvhead[off].pvh_lock);
 
        if (pve)
-               pmap_free_pv(pve);
+               pmap_free_pv(pmap, pve);
        return(TRUE);
 }
 
@@ -2389,7 +2401,7 @@
                }
                pmap_unmap_ptes(pve->pv_pmap);          /* unlocks pmap */
        }
-       pmap_free_pvs(pvh->pvh_list);
+       pmap_free_pvs(NULL, pvh->pvh_list);
        pvh->pvh_list = NULL;
        simple_unlock(&pvh->pvh_lock);
        PMAP_HEAD_TO_MAP_UNLOCK();
@@ -3312,7 +3324,7 @@
                /* new mapping is not PG_PVLIST.   free pve if we've got one */
                pvh = NULL;             /* ensure !PG_PVLIST */
                if (pve)
-                       pmap_free_pv(pve);
+                       pmap_free_pv(pmap, pve);
        }
 
 enter_now: