diff options
| -rw-r--r-- | mm/memcontrol.c | 29 |
1 files changed, 25 insertions, 4 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e4c8735e7c85..46d8d02114cf 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2623,8 +2623,9 @@ static unsigned long calculate_high_delay(struct mem_cgroup *memcg, } /* - * Scheduled by try_charge() to be executed from the userland return path - * and reclaims memory over the high limit. + * Reclaims memory over the high limit. Called directly from + * try_charge() (context permitting), as well as from the userland + * return path where reclaim is always able to block. */ void mem_cgroup_handle_over_high(gfp_t gfp_mask) { @@ -2644,6 +2645,17 @@ void mem_cgroup_handle_over_high(gfp_t gfp_mask) retry_reclaim: /* + * Bail if the task is already exiting. Unlike memory.max, + * memory.high enforcement isn't as strict, and there is no + * OOM killer involved, which means the excess could already + * be much bigger (and still growing) than it could for + * memory.max; the dying task could get stuck in fruitless + * reclaim for a long time, which isn't desirable. + */ + if (task_is_dying()) + goto out; + + /* * The allocating task should reclaim at least the batch size, but for * subsequent retries we only want to do what's necessary to prevent oom * or breaching resource isolation. @@ -2693,6 +2705,9 @@ retry_reclaim: } /* + * Reclaim didn't manage to push usage below the limit, slow + * this allocating task down. + * * If we exit early, we're guaranteed to die (since * schedule_timeout_killable sets TASK_KILLABLE). This means we don't * need to account for any ill-begotten jiffies to pay them off later. @@ -2887,11 +2902,17 @@ done_restock: } } while ((memcg = parent_mem_cgroup(memcg))); + /* + * Reclaim is set up above to be called from the userland + * return path. But also attempt synchronous reclaim to avoid + * excessive overrun while the task is still inside the + * kernel. If this is successful, the return path will see it + * when it rechecks the overage and simply bail out. + */ if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH && !(current->flags & PF_MEMALLOC) && - gfpflags_allow_blocking(gfp_mask)) { + gfpflags_allow_blocking(gfp_mask)) mem_cgroup_handle_over_high(gfp_mask); - } return 0; } |