[PATCH -v4] x86: do not free zero sized per cpu areas

[Yinghai Lu]

From: Ian Campbell <ian.campbell@xxxxxxxxxx>

This avoids an infinite loop in free_early_partial().

Add a warning to free_early_partial to catch future problems.

-v3: according to hpa, don't bother caller.
-v4: start == end is ok?

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
---
 kernel/early_res.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

Index: linux-2.6/kernel/early_res.c
===================================================================
--- linux-2.6.orig/kernel/early_res.c
+++ linux-2.6/kernel/early_res.c
@@ -333,6 +333,17 @@ void __init free_early_partial(u64 start
 	struct early_res *r;
 	int i;
 
+	if (start == end)
+		return;
+
+	if (start > end) {
+		WARN_ONCE(1,
+		      "free_early_partial got wrong start/end %#llx/%#llx\n",
+		      start, end);
+
+		return;
+	}
+
 try_next:
 	i = find_overlapped_early(start, end);
 	if (i >= max_early_res)

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