[PATCH] temporarily disable swap token on memory pressure

Some users (hi Zwane) have seen a problem when running a workload that
eats nearly all of physical memory - th system does an OOM kill, even
when there is still a lot of swap free.

The problem appears to be a very big task that is holding the swap
token, and the VM has a very hard time finding any other page in the
system that is swappable.

Instead of ignoring the swap token when sc->priority reaches 0, we could
simply take the swap token away from the memory hog and make sure we
don't give it back to the memory hog for a few seconds.

This patch resolves the problem Zwane ran into.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 20c975642cab..508668f840b6 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -239,6 +239,11 @@ static inline void put_swap_token(struct mm_struct *mm)
                 __put_swap_token(mm);
 }
 
+static inline void disable_swap_token(void)
+{
+        put_swap_token(swap_token_mm);
+}
+
 #else /* CONFIG_SWAP */
 
 #define total_swap_pages                        0
@@ -283,6 +288,7 @@ static inline swp_entry_t get_swap_page(void)
 #define put_swap_token(x) do { } while(0)
 #define grab_swap_token()  do { } while(0)
 #define has_swap_token(x) 0
+#define disable_swap_token() do { } while(0)
 
 #endif /* CONFIG_SWAP */
 #endif /* __KERNEL__*/