Commit fb0fec50 authored Dec 04, 2015 by Chris Wilson Committed by Daniel Vetter Jan 05, 2016

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>

parent 934acce3

mm/swapfile.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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;