Author: cognet
Date: Sat Mar 21 15:32:59 2015
New Revision: 280324
URL: https://svnweb.freebsd.org/changeset/base/280324
Log:
When waiting on PTE allocation, another thread could free the l2_dtable while
we're not looking at it.
Fix this by increasing l2->l2_occupancy before we try to alloc (and decrease
it if the allocation failed, or if another thread did a similar allocation).
Submitted by: Kohji Okuno <okuno.ko...@jp.panasonic.com>
MFC after: 1 week
Modified:
head/sys/arm/arm/pmap-v6.c
head/sys/arm/arm/pmap.c
Modified: head/sys/arm/arm/pmap-v6.c
==============================================================================
--- head/sys/arm/arm/pmap-v6.c Sat Mar 21 15:01:19 2015 (r280323)
+++ head/sys/arm/arm/pmap-v6.c Sat Mar 21 15:32:59 2015 (r280324)
@@ -758,6 +758,7 @@ pmap_alloc_l2_bucket(pmap_t pmap, vm_off
* No L2 page table has been allocated. Chances are, this
* is because we just allocated the l2_dtable, above.
*/
+ l2->l2_occupancy++;
PMAP_UNLOCK(pmap);
rw_wunlock(&pvh_global_lock);
ptep = uma_zalloc(l2zone, M_NOWAIT);
@@ -765,6 +766,7 @@ pmap_alloc_l2_bucket(pmap_t pmap, vm_off
PMAP_LOCK(pmap);
if (l2b->l2b_kva != 0) {
/* We lost the race. */
+ l2->l2_occupancy--;
uma_zfree(l2zone, ptep);
return (l2b);
}
@@ -775,6 +777,7 @@ pmap_alloc_l2_bucket(pmap_t pmap, vm_off
* time. We may need to deallocate the l2_dtable
* if we allocated a new one above.
*/
+ l2->l2_occupancy--;
if (l2->l2_occupancy == 0) {
pmap->pm_l2[L2_IDX(l1idx)] = NULL;
uma_zfree(l2table_zone, l2);
@@ -782,7 +785,6 @@ pmap_alloc_l2_bucket(pmap_t pmap, vm_off
return (NULL);
}
- l2->l2_occupancy++;
l2b->l2b_kva = ptep;
l2b->l2b_l1idx = l1idx;
}
Modified: head/sys/arm/arm/pmap.c
==============================================================================
--- head/sys/arm/arm/pmap.c Sat Mar 21 15:01:19 2015 (r280323)
+++ head/sys/arm/arm/pmap.c Sat Mar 21 15:32:59 2015 (r280324)
@@ -878,6 +878,7 @@ pmap_alloc_l2_bucket(pmap_t pm, vm_offse
* No L2 page table has been allocated. Chances are, this
* is because we just allocated the l2_dtable, above.
*/
+ l2->l2_occupancy++;
PMAP_UNLOCK(pm);
rw_wunlock(&pvh_global_lock);
ptep = uma_zalloc(l2zone, M_NOWAIT);
@@ -885,6 +886,7 @@ pmap_alloc_l2_bucket(pmap_t pm, vm_offse
PMAP_LOCK(pm);
if (l2b->l2b_kva != 0) {
/* We lost the race. */
+ l2->l2_occupancy--;
uma_zfree(l2zone, ptep);
return (l2b);
}
@@ -895,6 +897,7 @@ pmap_alloc_l2_bucket(pmap_t pm, vm_offse
* time. We may need to deallocate the l2_dtable
* if we allocated a new one above.
*/
+ l2->l2_occupancy--;
if (l2->l2_occupancy == 0) {
pm->pm_l2[L2_IDX(l1idx)] = NULL;
uma_zfree(l2table_zone, l2);
@@ -902,7 +905,6 @@ pmap_alloc_l2_bucket(pmap_t pm, vm_offse
return (NULL);
}
- l2->l2_occupancy++;
l2b->l2b_kva = ptep;
l2b->l2b_l1idx = l1idx;
}
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