logcache needs 2 entries at least

src/fellow_log.c

@@ -1179,6 +1179,8 @@ fellow_logcache_init(struct fellow_logcache *flc, struct fellow_fd *ffd,
 		n = (typeof(n))sz;
 	if (n > BUDDY_REQS_MAX)
 		n = BUDDY_REQS_MAX;
+	if (n < 2)
+		n = 2;	// fellow_logcache_(take|steal) assume 2 entries
 
 	INIT_OBJ(flc, FELLOW_LOGCACHE_MAGIC);
 	flc->ffd = ffd;
@@ -1192,7 +1194,8 @@ fellow_logcache_init(struct fellow_logcache *flc, struct fellow_fd *ffd,
 	sz = n * sizeof *fle;
 	u = log2up(sz);
 	l = log2up(sizeof *fle);
-	cram = (int)l - (int)u;
+	cram = ((int)l - (int)u) + 1;
+
 	assert(cram <= 0);
 
 	if (u > UINT8_MAX)
@@ -1215,7 +1218,7 @@ fellow_logcache_init(struct fellow_logcache *flc, struct fellow_fd *ffd,
 	for (u = 0; u < sz; u++)
 		AN(buddy_req_page(reqs, MIN_FELLOW_BITS, 0));
 	u = buddy_alloc_wait(reqs);
-	AN(u);
+	assert(u >= 2);
 	flc->n = u;
 
 	for (fle = flc->alloc_entry.ptr, u = 0;