- If swap metadata does not fit into the KVM, reduce the number of

struct swblock entries by dividing the number of the entries by 2
until the swap metadata fits.

- Reject swapon(2) upon failure of swap_zone allocation.

This is just a temporary fix. Better solutions include:
(suggested by:	dillon)

o reserving swap in SWAP_META_PAGES chunks, and
o swapping the swblock structures themselves.

Reviewed by:	alfred, dillon

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/vm/vm_swap.c b/sys/vm/vm_swap.c
index 8691c22..fada384 100644
--- a/sys/vm/vm_swap.c
+++ b/sys/vm/vm_swap.c
@@ -53,6 +53,7 @@
 #include <sys/stat.h>
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
+#include <vm/vm_zone.h>
 #include <vm/swap_pager.h>
 
 /*
@@ -194,6 +195,13 @@ swapon(p, uap)
 	if (error)
 		return (error);
 
+	/*
+	 * Swap metadata may not fit in the KVM if we have physical
+	 * memory of >1GB.
+	 */
+	if (swap_zone == NULL)
+		return (ENOMEM);
+
 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p);
 	error = namei(&nd);
 	if (error)