--- zzzz-none-000/linux-3.10.107/arch/um/kernel/tlb.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/um/kernel/tlb.c	2021-02-04 17:41:59.000000000 +0000
@@ -12,6 +12,7 @@
 #include <mem_user.h>
 #include <os.h>
 #include <skas.h>
+#include <kern_util.h>
 
 struct host_vm_change {
 	struct host_vm_op {
@@ -49,6 +50,13 @@
 	   .index	= 0, \
 	   .force	= force })
 
+static void report_enomem(void)
+{
+	printk(KERN_ERR "UML ran out of memory on the host side! "
+			"This can happen due to a memory limitation or "
+			"vm.max_map_count has been reached.\n");
+}
+
 static int do_ops(struct host_vm_change *hvc, int end,
 		  int finished)
 {
@@ -80,6 +88,9 @@
 		}
 	}
 
+	if (ret == -ENOMEM)
+		report_enomem();
+
 	return ret;
 }
 
@@ -124,6 +135,9 @@
 	struct host_vm_op *last;
 	int ret = 0;
 
+	if ((addr >= STUB_START) && (addr < STUB_END))
+		return -EINVAL;
+
 	if (hvc->index != 0) {
 		last = &hvc->ops[hvc->index - 1];
 		if ((last->type == MUNMAP) &&
@@ -283,8 +297,11 @@
 	/* This is not an else because ret is modified above */
 	if (ret) {
 		printk(KERN_ERR "fix_range_common: failed, killing current "
-		       "process\n");
+		       "process: %d\n", task_tgid_vnr(current));
+		/* We are under mmap_sem, release it such that current can terminate */
+		up_write(&current->mm->mmap_sem);
 		force_sig(SIGKILL, current);
+		do_signal(&current->thread.regs);
 	}
 }
 
@@ -426,8 +443,12 @@
 	else if (pte_newprot(*pte))
 		err = protect(mm_id, address, PAGE_SIZE, prot, 1, &flush);
 
-	if (err)
+	if (err) {
+		if (err == -ENOMEM)
+			report_enomem();
+
 		goto kill;
+	}
 
 	*pte = pte_mkuptodate(*pte);