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

[Bruce Ashfield]

On 2016-07-11 05:29 PM, Eric Ernst wrote:
> 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.

merged to standard/intel/*

Bruce

>
> 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;
>