[linux-yocto] [PATCH 1/1] UPSTREAM: mm: Export nr_swap_pages

[Eric Ernst]

From: Chris Wilson <chris at chris-wilson.co.uk>

Some modules, like i915.ko, use swappable objects and may try to swap
them out under memory pressure (via the shrinker). Before doing so, they
want to check using get_nr_swap_pages() to see if any swap space is
available as otherwise they will waste time purging the object from the
device without recovering any memory for the system. This requires the
nr_swap_pages counter to be exported to the modules.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: "Goel, Akash" <akash.goel at intel.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: linux-mm at kvack.org
Link: http://patchwork.freedesktop.org/patch/msgid/1449244734-25733-1-git-send-email-chris@chris-wilson.co.uk
Acked-by: Andrew Morton <akpm at linux-foundation.org>
Acked-by: Johannes Weiner <hannes at cmpxchg.org>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

(pulled from 4.6-rc1)
Signed-off-by: Eric Ernst <eric.ernst at linux.intel.com>
---
 mm/swapfile.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 58877312cf6b..2d259fdb2347 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -48,6 +48,12 @@ static sector_t map_swap_entry(swp_entry_t, struct block_device**);
 DEFINE_SPINLOCK(swap_lock);
 static unsigned int nr_swapfiles;
 atomic_long_t nr_swap_pages;
+/*
+ * Some modules use swappable objects and may try to swap them out under
+ * memory pressure (via the shrinker). Before doing so, they may wish to
+ * check to see if any swap space is available.
+ */
+EXPORT_SYMBOL_GPL(nr_swap_pages);
 /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
 long total_swap_pages;
 static int least_priority;
-- 
1.9.1