[PATCH] mm/page_alloc: replace local_lock with normal spinlock -fix -fix

[Mel Gorman]

pcpu_spin_unlock and pcpu_spin_unlock_irqrestore both unlock
pcp->lock and then enable preemption. This lacks symmetry against
both the pcpu_spin helpers and differs from how local_unlock_* is
implemented. While this is harmless, it's unnecessary and it's generally
better to unwind locks and preemption state in the reverse order as
they were acquired.

This is a fix on top of the mm-unstable patch
mm-page_alloc-replace-local_lock-with-normal-spinlock-fix.patch

Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
 mm/page_alloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 934d1b5a5449..d0141e51e613 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -192,14 +192,14 @@ static DEFINE_MUTEX(pcp_batch_high_lock);
 
 #define pcpu_spin_unlock(member, ptr)					\
 ({									\
-	spin_unlock(&ptr->member);					\
 	pcpu_task_unpin();						\
+	spin_unlock(&ptr->member);					\
 })
 
 #define pcpu_spin_unlock_irqrestore(member, ptr, flags)			\
 ({									\
-	spin_unlock_irqrestore(&ptr->member, flags);			\
 	pcpu_task_unpin();						\
+	spin_unlock_irqrestore(&ptr->member, flags);			\
 })
 
 /* struct per_cpu_pages specific helpers. */