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authorChris Wilson <chris@chris-wilson.co.uk>2015-12-04 15:58:53 +0000
committerDaniel Vetter <daniel.vetter@ffwll.ch>2016-01-05 11:02:18 +0100
commitfb0fec501f08a0a83af7a2b25888ec8cebab53b0 (patch)
tree82f78ea91951ae741276fad297ab96ea4638a0c7 /mm/swapfile.c
parent934acce3c069a3d8b14085957248444145d9ec1b (diff)
mm: Export nr_swap_pages
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@chris-wilson.co.uk> Cc: "Goel, Akash" <akash.goel@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: linux-mm@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@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c6
1 files changed, 6 insertions, 0 deletions
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;