If a process is over its resource limit for datasize, still allow

it to lower its memory usage. This was mentioned on the mailing
lists ages ago, and I've lost the name of the person who brought
it up.

Reviewed by:	alc

1 files changed, 7 insertions, 3 deletions

diff --git a/sys/vm/vm_unix.c b/sys/vm/vm_unix.c
index d5e9f58aab60..bea87f07be60 100644
--- a/sys/vm/vm_unix.c
+++ b/sys/vm/vm_unix.c
@@ -73,8 +73,14 @@ obreak(p, uap)
 
 	base = round_page((vm_offset_t) vm->vm_daddr);
 	new = round_page((vm_offset_t)uap->nsize);
+	old = base + ctob(vm->vm_dsize);
 	if (new > base) {
-		if ((new - base) > (unsigned) p->p_rlimit[RLIMIT_DATA].rlim_cur)
+		/*
+		 * We check resource limits here, but alow processes to
+		 * reduce their usage, even if they remain over the limit.
+		 */
+		if (new > old &&
+		    (new - base) > (unsigned) p->p_rlimit[RLIMIT_DATA].rlim_cur)
 			return ENOMEM;
 		if (new >= VM_MAXUSER_ADDRESS)
 			return (ENOMEM);
@@ -87,8 +93,6 @@ obreak(p, uap)
 		return EINVAL;
 	}
 
-	old = base + ctob(vm->vm_dsize);
-
 	if (new > old) {
 		vm_size_t diff;