linux-kernel - [15/24] trace: Fix inappropriate substraction on tracing_pages_allocated in trace_free

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Date:	Mon, 24 May 2010 15:28:11 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org,
	Greg KH <greg@...ah.com>
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>, Li Zefan <lizf@...fujitsu.com>,
	Wang Sheng-Hui <crosslonelyover@...il.com>
Subject: [15/24] trace: Fix inappropriate substraction on tracing_pages_allocated in trace_free_page()

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Wang Sheng-Hui <crosslonelyover@...il.com>

[No matching upstream git commit id as it was fixed differently due to a
rewrite of the tracing code there.]

For normal case, the code in trace_free_page() do once more substraction
on tracing_pages_allocated, but for CONFIG_TRACER_MAX_TRACE  it doesn't
take the freed page into account. That's not consistent with
trace_alloc_page().  Well, for there are no message related with this,
so we cannot observe its incorrect state when the kernel doesn't define
"CONFIG_TRACER_MAX_TRACE". If you add some pr_info() as
trace_alloc_page(), you may notice it.

Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Li Zefan <lizf@...fujitsu.com>
Signed-off-by: Wang Sheng-Hui <crosslonelyover@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 kernel/trace/trace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3018,7 +3018,6 @@ static int trace_free_page(void)
 		ClearPageLRU(page);
 		list_del(&page->lru);
 		tracing_pages_allocated--;
-		tracing_pages_allocated--;
 		__free_page(page);
 
 		tracing_reset(data);
@@ -3036,6 +3035,7 @@ static int trace_free_page(void)
 		page = list_entry(p, struct page, lru);
 		ClearPageLRU(page);
 		list_del(&page->lru);
+		tracing_pages_allocated--;
 		__free_page(page);
 
 		tracing_reset(data);


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