From: Juergen Gross <jgross@suse.com>
Date: Mon, 18 Jul 2016 14:46:11 +0000 (+0200)
Subject: mini-os: let memory allocation fail if no free page available
X-Git-Tag: xen-4.8.0-rc1~64
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=03d8b0f12b07ec914da9e6c258e1a1c7ac5d86f8;p=mini-os.git

mini-os: let memory allocation fail if no free page available

Instead of panicing when no page can be allocated try to fail the
memory allocation by returning NULL instead.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---

diff --git a/mm.c b/mm.c
index 263a356..8cf3210 100644
--- a/mm.c
+++ b/mm.c
@@ -335,6 +335,13 @@ void *sbrk(ptrdiff_t increment)
     
     if (new_brk > heap_mapped) {
         unsigned long n = (new_brk - heap_mapped + PAGE_SIZE - 1) / PAGE_SIZE;
+
+        if ( n > nr_free_pages )
+        {
+            printk("Memory exhausted: want %ld pages, but only %ld are left\n",
+                   n, nr_free_pages);
+            return NULL;
+        }
         do_map_zero(heap_mapped, n);
         heap_mapped += n * PAGE_SIZE;
     }