[PATCH 3/3] mm: catch memory commitment underflow

Konstantin Khlebnikov
2014-06-24T20:16:21Z

This patch prints warning (if CONFIG_DEBUG_VM=y) when
memory commitment becomes too negative.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
---
mm/mmap.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index 129b847..d3decd9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -134,6 +134,12 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
{
unsigned long free, allowed, reserve;

+#ifdef CONFIG_DEBUG_VM
+ WARN_ONCE(percpu_counter_read(&vm_committed_as) <
+ -(s64)vm_committed_as_batch * num_online_cpus(),
+ "memory commitment underflow");
+#endif
+
vm_acct_memory(pages);

/*