[PATCH 1/4] x86: do not free zero sized per cpu areas

[Yinghai Lu <yinghai@kernel.org>]

From: Ian Campbell <ian.campbell@citrix.com>

This avoids an infinite loop in free_early_partial().

Add a warning to free_early_partial to catch future problems.

-v5: put back start > end back into WARN_ONCE()
-v6: use one line for if according to linus

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
 kernel/early_res.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/early_res.c b/kernel/early_res.c
index 3cb2c66..69bed5b 100644
--- a/kernel/early_res.c
+++ b/kernel/early_res.c
@@ -333,6 +333,12 @@ void __init free_early_partial(u64 start, u64 end)
 	struct early_res *r;
 	int i;
 
+	if (start == end)
+		return;
+
+	if (WARN_ONCE(start > end, "free_early_partial: wrong range [%#llx, %#llx]\n", start, end))
+		return;
+
 try_next:
 	i = find_overlapped_early(start, end);
 	if (i >= max_early_res)
-- 
1.6.4.2