[PATCH] percpu: convert spin_lock_irq to spin_lock_irqsave.

[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().
---
 mm/percpu-km.c | 5 +++--
 1 file 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);
-- 
2.11.0


--jnbswjcdwgcvwuta--