[ 033/184] tracing: Dont call page_to_pfn() if page is NULL

From: Willy Tarreau
Date: Tue Jun 04 2013 - 19:18:56 EST

2.6.32-longterm review patch. If anyone has any objections, please let me know.


From: Wen Congyang <wency@xxxxxxxxxxxxxx>

commit 85f2a2ef1d0ab99523e0b947a2b723f5650ed6aa upstream.

When allocating memory fails, page is NULL. page_to_pfn() will
cause the kernel panicked if we don't use sparsemem vmemmap.

Link: http://lkml.kernel.org/r/505AB1FF.8020104@xxxxxxxxxxxxxx

Acked-by: Mel Gorman <mel@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
include/trace/events/kmem.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index eaf46bd..a8dc32a 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -293,7 +293,7 @@ TRACE_EVENT(mm_page_alloc,

TP_printk("page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s",
- page_to_pfn(__entry->page),
+ __entry->page ? page_to_pfn(__entry->page) : 0,
@@ -319,7 +319,7 @@ TRACE_EVENT(mm_page_alloc_zone_locked,

TP_printk("page=%p pfn=%lu order=%u migratetype=%d percpu_refill=%d",
- page_to_pfn(__entry->page),
+ __entry->page ? page_to_pfn(__entry->page) : 0,
__entry->order == 0)

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