static void __exit lowmem_exit(void) { unregister_shrinker(&lowmem_shrinker); task_free_unregister(&task_nb); }
static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask) { struct task_struct *p; struct task_struct *selected = NULL; int rem = 0; int tasksize; int i; int min_adj = OOM_ADJUST_MAX + 1; int selected_tasksize = 0; int selected_oom_adj; int array_size = ARRAY_SIZE(lowmem_adj); int other_free = global_page_state(NR_FREE_PAGES); int other_file = global_page_state(NR_FILE_PAGES); int lru_file = global_page_state(NR_ACTIVE_FILE) + global_page_state(NR_INACTIVE_FILE); /* * If we already have a death outstanding, then * bail out right away; indicating to vmscan * that we have nothing further to offer on * this pass. * */ if (lowmem_deathpending) { dump_deathpending(lowmem_deathpending); if (lowmem_deathpending_retries++ < lowmem_max_deathpending_retries) return 0; else task_free_unregister(&task_nb); } if (lowmem_adj_size < array_size) array_size = lowmem_adj_size; if (lowmem_minfree_size < array_size) array_size = lowmem_minfree_size; for (i = 0; i < array_size; i++) { if (other_free < lowmem_minfree[i]) { if(other_file < lowmem_minfree[i] || (lowmem_check_filepages && (lru_file < lowmem_minfile[i]))) { min_adj = lowmem_adj[i]; break; } } } if (nr_to_scan > 0) lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n", nr_to_scan, gfp_mask, other_free, other_file, min_adj); rem = global_page_state(NR_ACTIVE_ANON) + global_page_state(NR_ACTIVE_FILE) + global_page_state(NR_INACTIVE_ANON) + global_page_state(NR_INACTIVE_FILE); if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) { lowmem_print(5, "lowmem_shrink %d, %x, return %d\n", nr_to_scan, gfp_mask, rem); return rem; } selected_oom_adj = min_adj; read_lock(&tasklist_lock); for_each_process(p) { struct mm_struct *mm; struct signal_struct *sig; int oom_adj; if (p == lowmem_deathpending) { lowmem_print(2, "skip death pending task %d (%s)\n", p->pid, p->comm); continue; } task_lock(p); mm = p->mm; sig = p->signal; if (!mm || !sig) { task_unlock(p); continue; } oom_adj = sig->oom_adj; if (oom_adj < min_adj) { task_unlock(p); continue; } tasksize = get_mm_rss(mm); task_unlock(p); if (tasksize <= 0) continue; if (selected) { if (oom_adj < selected_oom_adj) continue; if (oom_adj == selected_oom_adj && tasksize <= selected_tasksize) continue; } selected = p; selected_tasksize = tasksize; selected_oom_adj = oom_adj; lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n", p->pid, p->comm, oom_adj, tasksize); } if (selected) { lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n", selected->pid, selected->comm, selected_oom_adj, selected_tasksize); if (!ignore_lowmem_deathpending) { lowmem_deathpending = selected; lowmem_deathpending_retries = 0; task_free_register(&task_nb); } force_sig(SIGKILL, selected); rem -= selected_tasksize; } else { lowmem_deathpending = NULL; } lowmem_print(4, "lowmem_shrink %d, %x, return %d\n", nr_to_scan, gfp_mask, rem); read_unlock(&tasklist_lock); return rem; }