percpu: fix early calls for spinlock in pcpu_stats

From 2c06e795162cb306c9707ec51d3e1deadb37f573 Mon Sep 17 00:00:00 2001
From: Dennis Zhou <dennisz@fb.com>
Date: Wed, 21 Jun 2017 10:17:09 -0700

Commit 30a5b5367ef9 ("percpu: expose statistics about percpu memory via
debugfs") introduces percpu memory statistics. pcpu_stats_chunk_alloc
takes the spin lock and disables/enables irqs on creation of a chunk. Irqs
are not enabled when the first chunk is initialized and thus kernels are
failing to boot with kernel debugging enabled. Fixed by changing _irq to
_irqsave and _irqrestore.

Fixes: 30a5b5367ef9 ("percpu: expose statistics about percpu memory via debugfs")
Signed-off-by: Dennis Zhou <dennisz@fb.com>
Reported-by: Alexander Levin <alexander.levin@verizon.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h
index d030fce745a2..cd2442e13d8f 100644
--- a/mm/percpu-internal.h
+++ b/mm/percpu-internal.h
@@ -116,13 +116,14 @@ static inline void pcpu_stats_area_dealloc(struct pcpu_chunk *chunk)
  */
 static inline void pcpu_stats_chunk_alloc(void)
 {
-        spin_lock_irq(&pcpu_lock);
+        unsigned long flags;
+        spin_lock_irqsave(&pcpu_lock, flags);
 
         pcpu_stats.nr_chunks++;
         pcpu_stats.nr_max_chunks =
                 max(pcpu_stats.nr_max_chunks, pcpu_stats.nr_chunks);
 
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 }
 
 /*
@@ -130,11 +131,12 @@ static inline void pcpu_stats_chunk_alloc(void)
  */
 static inline void pcpu_stats_chunk_dealloc(void)
 {
-        spin_lock_irq(&pcpu_lock);
+        unsigned long flags;
+        spin_lock_irqsave(&pcpu_lock, flags);
 
         pcpu_stats.nr_chunks--;
 
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 }
 
 #else