mm: memcontrol: hook up vmpressure to socket pressure

Let the networking stack know when a memcg is under reclaim pressure so
that it can clamp its transmit windows accordingly.

Whenever the reclaim efficiency of a cgroup's LRU lists drops low enough
for a MEDIUM or HIGH vmpressure event to occur, assert a pressure state
in the socket and tcp memory code that tells it to curb consumption
growth from sockets associated with said control group.

Traditionally, vmpressure reports for the entire subtree of a memcg
under pressure, which drops useful information on the individual groups
reclaimed.  However, it's too late to change the userinterface, so add a
second reporting mode that reports on the level of reclaim instead of at
the level of pressure, and use that report for sockets.

vmpressure events are naturally edge triggered, so for hysteresis assert
socket pressure for a second to allow for subsequent vmpressure events
to occur before letting the socket code return to normal.

This will likely need finetuning for a wider variety of workloads, but
for now stick to the vmpressure presets and keep hysteresis simple.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/vmpressure.h b/include/linux/vmpressure.h
index 3e4535876d37..3347cc3ec0ab 100644
--- a/include/linux/vmpressure.h
+++ b/include/linux/vmpressure.h
@@ -12,6 +12,9 @@
 struct vmpressure {
 	unsigned long scanned;
 	unsigned long reclaimed;
+
+	unsigned long tree_scanned;
+	unsigned long tree_reclaimed;
 	/* The lock is used to keep the scanned/reclaimed above in sync. */
 	struct spinlock sr_lock;
 
@@ -26,7 +29,7 @@ struct vmpressure {
 struct mem_cgroup;
 
 #ifdef CONFIG_MEMCG
-extern void vmpressure(gfp_t gfp, struct mem_cgroup *memcg,
+extern void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
 		       unsigned long scanned, unsigned long reclaimed);
 extern void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio);
 
@@ -40,7 +43,7 @@ extern int vmpressure_register_event(struct mem_cgroup *memcg,
 extern void vmpressure_unregister_event(struct mem_cgroup *memcg,
 					struct eventfd_ctx *eventfd);
 #else
-static inline void vmpressure(gfp_t gfp, struct mem_cgroup *memcg,
+static inline void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
 			      unsigned long scanned, unsigned long reclaimed) {}
 static inline void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg,
 				   int prio) {}