# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1258025991 0
# Node ID 368cfc61e7b6993bb599ebf7b0bafb78d245852b
# Parent 01a941f2c9f5d7ab73436b44977695a9e4ea0060
PoD: Handle operations properly when domain is dying
No populate-on-demand activities should happen when a domain is dying.
Especially, it is a bug for memory to be added to the PoD cache when
d->is_dying is non-zero, since if this happens after the cache has
been emptied, these pages will never be freed. This may cause "zombie
domains" to linger.
Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
xen/arch/x86/mm/p2m.c | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletion(-)
diff -r 01a941f2c9f5 -r 368cfc61e7b6 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c Wed Nov 11 13:11:44 2009 +0000
+++ b/xen/arch/x86/mm/p2m.c Thu Nov 12 11:39:51 2009 +0000
@@ -302,6 +302,8 @@ p2m_pod_cache_add(struct domain *d,
default:
BUG();
}
+
+ BUG_ON(d->is_dying);
spin_unlock(&d->page_alloc_lock);
@@ -503,6 +505,10 @@ p2m_pod_set_mem_target(struct domain *d,
if ( p2md->pod.entry_count == 0 )
goto out;
+ /* Don't do anything if the domain is being torn down */
+ if ( d->is_dying )
+ goto out;
+
/* T' < B: Don't reduce the cache size; let the balloon driver
* take care of it. */
if ( target < d->tot_pages )
@@ -582,7 +588,7 @@ p2m_pod_decrease_reservation(struct doma
/* If we don't have any outstanding PoD entries, let things take their
* course */
- if ( p2md->pod.entry_count == 0 )
+ if ( p2md->pod.entry_count == 0 || unlikely(d->is_dying) )
goto out;
/* Figure out if we need to steal some freed memory for our cache */
@@ -1002,6 +1008,12 @@ p2m_pod_demand_populate(struct domain *d
struct p2m_domain *p2md = d->arch.p2m;
int i;
+ /* This check is done with the p2m lock held. This will make sure that
+ * even if d->is_dying changes under our feet, empty_pod_cache() won't
start
+ * until we're done. */
+ if ( unlikely(d->is_dying) )
+ goto out_fail;
+
/* If we're low, start a sweep */
if ( order == 9 && page_list_empty(&p2md->pod.super) )
p2m_pod_emergency_sweep_super(d);
@@ -1048,6 +1060,7 @@ out_of_memory:
printk("%s: Out of populate-on-demand memory! tot_pages %" PRIu32 "
pod_entries %" PRIi32 "\n",
__func__, d->tot_pages, p2md->pod.entry_count);
domain_crash(d);
+out_fail:
return -1;
remap_and_retry:
BUG_ON(order != 9);
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