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Subject[tip:core/locking-v2] lockdep: fix deadlock in lockdep_trace_alloc
Commit-ID:  2f8501815256af8498904e68bd0984b1afffd6f8
Gitweb: http://git.kernel.org/tip/2f8501815256af8498904e68bd0984b1afffd6f8
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Fri, 20 Mar 2009 11:13:20 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 30 Mar 2009 23:19:24 +0200

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@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <npiggin@suse.de>
LKML-Reference: <1237544000.24626.52.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/lockdep.c | 21 +++++++++++++++++++--
1 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 022d2ed..3673a3f 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2260,7 +2260,7 @@ 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, unsigned long flags)
{
struct task_struct *curr = current;

@@ -2279,12 +2279,29 @@ void lockdep_trace_alloc(gfp_t gfp_mask)
if (!(gfp_mask & __GFP_FS))
return;

- if (DEBUG_LOCKS_WARN_ON(irqs_disabled()))
+ if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
return;

mark_held_locks(curr, RECLAIM_FS);
}

+static void check_flags(unsigned long flags);
+
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ check_flags(flags);
+ current->lockdep_recursion = 1;
+ __lockdep_trace_alloc(gfp_mask, flags);
+ 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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