- wakeups = atomic_read(&memcg->oom_wakeups);
- mem_cgroup_mark_under_oom(memcg);
-
- locked = mem_cgroup_oom_trylock(memcg);
-
- if (locked)
- mem_cgroup_oom_notify(memcg);
-
- if (locked && !memcg->oom_kill_disable) {
- mem_cgroup_unmark_under_oom(memcg);
- mem_cgroup_out_of_memory(memcg, mask, order);
- mem_cgroup_oom_unlock(memcg);
- /*
- * There is no guarantee that an OOM-lock contender
- * sees the wakeups triggered by the OOM kill
- * uncharges. Wake any sleepers explicitely.
- */
- memcg_oom_recover(memcg);
- } else {
- /*
- * A system call can just return -ENOMEM, but if this
- * is a page fault and somebody else is handling the
- * OOM already, we need to sleep on the OOM waitqueue
- * for this memcg until the situation is resolved.
- * Which can take some time because it might be
- * handled by a userspace task.
- *
- * However, this is the charge context, which means
- * that we may sit on a large call stack and hold
- * various filesystem locks, the mmap_sem etc. and we
- * don't want the OOM handler to deadlock on them
- * while we sit here and wait. Store the current OOM
- * context in the task_struct, then return -ENOMEM.
- * At the end of the page fault handler, with the
- * stack unwound, pagefault_out_of_memory() will check
- * back with us by calling
- * mem_cgroup_oom_synchronize(), possibly putting the
- * task to sleep.
- */
- current->memcg_oom.oom_locked = locked;
- current->memcg_oom.wakeups = wakeups;
- css_get(&memcg->css);
- current->memcg_oom.wait_on_memcg = memcg;
- }