path: root/mm/swapfile.c
diff options
authorHugh Dickins <hughd@google.com>2012-05-29 15:06:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-29 16:22:22 -0700
commitbde05d1ccd512696b09db9dd2e5f33ad19152605 (patch)
treeaffa2c836136cac6ec0e503ce8996670d385ebbb /mm/swapfile.c
parent5ceb9ce6fe9462a298bb2cd5c9f1ca6cb80a0199 (diff)
shmem: replace page if mapping excludes its zone
The GMA500 GPU driver uses GEM shmem objects, but with a new twist: the backing RAM has to be below 4GB. Not a problem while the boards supported only 4GB: but now Intel's D2700MUD boards support 8GB, and their GMA3600 is managed by the GMA500 driver. shmem/tmpfs has never pretended to support hardware restrictions on the backing memory, but it might have appeared to do so before v3.1, and even now it works fine until a page is swapped out then back in. When read_cache_page_gfp() supplied a freshly allocated page for copy, that compensated for whatever choice might have been made by earlier swapin readahead; but swapoff was likely to destroy the illusion. We'd like to continue to support GMA500, so now add a new shmem_should_replace_page() check on the zone when about to move a page from swapcache to filecache (in swapin and swapoff cases), with shmem_replace_page() to allocate and substitute a suitable page (given gma500/gem.c's mapping_set_gfp_mask GFP_KERNEL | __GFP_DMA32). This does involve a minor extension to mem_cgroup_replace_page_cache() (the page may or may not have already been charged); and I've removed a comment and call to mem_cgroup_uncharge_cache_page(), which in fact is always a no-op while PageSwapCache. Also removed optimization of an unlikely path in shmem_getpage_gfp(), now that we need to check PageSwapCache more carefully (a racing caller might already have made the copy). And at one point shmem_unuse_inode() needs to use the hitherto private page_swapcount(), to guard against racing with inode eviction. It would make sense to extend shmem_should_replace_page(), to cover cpuset and NUMA mempolicy restrictions too, but set that aside for now: needs a cleanup of shmem mempolicy handling, and more testing, and ought to handle swap faults in do_swap_page() as well as shmem. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@infradead.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Stephane Marchesin <marcheu@chromium.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Airlie <airlied@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Rob Clark <rob.clark@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index fafc26d1b1d..b0c86e92f42 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -601,7 +601,7 @@ void swapcache_free(swp_entry_t entry, struct page *page)
* This does not give an exact answer when swap count is continued,
* but does include the high COUNT_CONTINUED flag to allow for that.
-static inline int page_swapcount(struct page *page)
+int page_swapcount(struct page *page)
int count = 0;
struct swap_info_struct *p;