linux-kernel - lockdep: fix deadlock in lockdep_trace

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Message-Id: <1237544000.24626.52.camel@twins>
Date:	Fri, 20 Mar 2009 11:13:20 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Heiko Carstens <heiko.carstens@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>
Cc:	Nick Piggin <npiggin@...e.de>,
	"lkml," <linux-kernel@...r.kernel.org>
Subject: lockdep: fix deadlock in lockdep_trace_alloc

Heiko reported that we grab the graph lock with irqs enabled.

Fix this by providng the same wrapper as all other lockdep entry
functions have.

Reported-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 3e1cc47..a39cb6d 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2258,7 +2258,7 @@ void trace_softirqs_off(unsigned long ip)
 		debug_atomic_inc(&redundant_softirqs_off);
 }
 
-void lockdep_trace_alloc(gfp_t gfp_mask)
+static void __lockdep_trace_alloc(gfp_t gfp_mask)
 {
 	struct task_struct *curr = current;
 
@@ -2283,6 +2283,20 @@ void lockdep_trace_alloc(gfp_t gfp_mask)
 	mark_held_locks(curr, RECLAIM_FS);
 }
 
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	current->lockdep_recursion = 1;
+	__lockdep_trace_alloc(gfp_mask);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+
 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
 {
 	/*

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