mm/memcg: move penalty delay clamping out of calculate_high_delay()

We will want to call calculate_high_delay() twice - once for memory and
once for swap, and we should apply the clamp value to sum of the
penalties.  Clamping has to be applied outside of calculate_high_delay().

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chris Down <chris@chrisdown.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20200527195846.102707-3-kuba@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b0ac90d..6a857b8 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2386,14 +2386,7 @@ static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
         * MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or
         * larger the current charge patch is than that.
         */
-       penalty_jiffies = penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
-
-       /*
-        * Clamp the max delay per usermode return so as to still keep the
-        * application moving forwards and also permit diagnostics, albeit
-        * extremely slowly.
-        */
-       return min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
+       return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
 }
 
 /*
@@ -2421,6 +2414,13 @@ void mem_cgroup_handle_over_high(void)
        penalty_jiffies = calculate_high_delay(memcg, nr_pages,
                                               mem_find_max_overage(memcg));
 
+       /*
+        * Clamp the max delay per usermode return so as to still keep the
+        * application moving forwards and also permit diagnostics, albeit
+        * extremely slowly.
+        */
+       penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
+
        /*
         * Don't sleep if the amount of jiffies this memcg owes us is so low
         * that it's not even worth doing, in an attempt to be nice to those who