From fb0fec501f08a0a83af7a2b25888ec8cebab53b0 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 4 Dec 2015 15:58:53 +0000 Subject: [PATCH] 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 Cc: "Goel, Akash" Cc: Johannes Weiner 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 Acked-by: Johannes Weiner Signed-off-by: Daniel Vetter --- 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;