[PATCH 4.19 172/313] percpu: convert spin_lock_irq to spin_lock_irqsave.

Greg Kroah-Hartman
2019-02-11T14:46:46Z

[ Upstream commit 6ab7d47bcbf0144a8cb81536c2cead4cde18acfe ]

>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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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);
--
2.19.1