[PATCH -v6] x86: do not free zero sized per cpu areas

From: Yinghai Lu <yinghai@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org,
	Ian Campbell <ian.campbell@citrix.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH -v6] x86: do not free zero sized per cpu areas
Date: Fri, 19 Mar 2010 23:38:30 -0700	[thread overview]
Message-ID: <4BA46D66.3050306@kernel.org> (raw)
In-Reply-To: <alpine.LFD.2.00.1003191940060.18017@i5.linux-foundation.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 file changed, 6 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 +333,12 @@ void __init free_early_partial(u64 start
 	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)
