um: Report host OOM more nicely

If UML runs on the host side out of memory, report this
condition more nicely.

Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 2077248e8a72..3777b82759bd 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -50,6 +50,13 @@ struct host_vm_change {
            .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)
 {
@@ -81,6 +88,9 @@ static int do_ops(struct host_vm_change *hvc, int end,
                 }
         }
 
+        if (ret == -ENOMEM)
+                report_enomem();
+
         return ret;
 }
 
@@ -433,8 +443,12 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
         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);