percpu: convert spin_lock_irq to spin_lock_irqsave.

From Michael Cree:
  "Bisection lead to commit b38d08f3181c ("percpu: restructure
   locking") as being the cause of lockups at initial boot on
   the kernel built for generic Alpha.

   On a suggestion by Tejun Heo that:

   So, the only thing I can think of is that it's calling
   spin_unlock_irq() while irq handling isn't set up yet.
   Can you please try the followings?

   1. Convert all spin_[un]lock_irq() to
      spin_lock_irqsave/unlock_irqrestore()."

Fixes: b38d08f3181c ("percpu: restructure locking")
Reported-and-tested-by: Michael Cree <mcree@orcon.net.nz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/mm/percpu-km.c b/mm/percpu-km.c
index 38de70ab1a0d..0f643dc2dc65 100644
--- a/mm/percpu-km.c
+++ b/mm/percpu-km.c
@@ -50,6 +50,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
         const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
         struct pcpu_chunk *chunk;
         struct page *pages;
+        unsigned long flags;
         int i;
 
         chunk = pcpu_alloc_chunk(gfp);
@@ -68,9 +69,9 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
         chunk->data = pages;
         chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
 
-        spin_lock_irq(&pcpu_lock);
+        spin_lock_irqsave(&pcpu_lock, flags);
         pcpu_chunk_populated(chunk, 0, nr_pages, false);
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 
         pcpu_stats_chunk_alloc();
         trace_percpu_create_chunk(chunk->base_addr);