// SPDX-License-Identifier: GPL-2.0 #include <linux/idr.h> #include <linux/slab.h> #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/shrinker.h> #include <linux/memcontrol.h> #include "internal.h" /* defined in vmscan.c */ extern struct mutex shrinker_mutex; extern struct list_head shrinker_list; static DEFINE_IDA(shrinker_debugfs_ida); static struct dentry *shrinker_debugfs_root; static unsigned long shrinker_count_objects(struct shrinker *shrinker, struct mem_cgroup *memcg, unsigned long *count_per_node) { unsigned long nr, total = 0; int nid; for_each_node(nid) { if (nid == 0 || (shrinker->flags & SHRINKER_NUMA_AWARE)) { struct shrink_control sc = { .gfp_mask = GFP_KERNEL, .nid = nid, .memcg = memcg, }; nr = shrinker->count_objects(shrinker, &sc); if (nr == SHRINK_EMPTY) nr = 0; } else { nr = 0; } count_per_node[nid] = nr; total += nr; } return total; } static int shrinker_debugfs_count_show(struct seq_file *m, void *v) { struct shrinker *shrinker = m->private; unsigned long *count_per_node; struct mem_cgroup *memcg; unsigned long total; bool memcg_aware; int ret = 0, nid; count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL); if (!count_per_node) return -ENOMEM; rcu_read_lock(); memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE; memcg = mem_cgroup_iter(NULL, NULL, NULL); do { if (memcg && !mem_cgroup_online(memcg)) continue; total = shrinker_count_objects(shrinker, memcg_aware ? memcg : NULL, count_per_node); if (total) { seq_printf(m, "%lu", mem_cgroup_ino(memcg)); for_each_node(nid) seq_printf(m, " %lu", count_per_node[nid]); seq_putc(m, '\n'); } if (!memcg_aware) { mem_cgroup_iter_break(NULL, memcg); break; } if (signal_pending(current)) { mem_cgroup_iter_break(NULL, memcg); ret = -EINTR; break; } } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); rcu_read_unlock(); kfree(count_per_node); return ret; } DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count); static int shrinker_debugfs_scan_open(struct inode *inode, struct file *file) { file->private_data = inode->i_private; return nonseekable_open(inode, file); } static ssize_t shrinker_debugfs_scan_write(struct file *file, const char __user *buf, size_t size, loff_t *pos) { struct shrinker *shrinker = file->private_data; unsigned long nr_to_scan = 0, ino, read_len; struct shrink_control sc = { .gfp_mask = GFP_KERNEL, }; struct mem_cgroup *memcg = NULL; int nid; char kbuf[72]; read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); if (copy_from_user(kbuf, buf, read_len)) return -EFAULT; kbuf[read_len] = '\0'; if (sscanf(kbuf, "%lu %d %lu", &ino, &nid, &nr_to_scan) != 3) return -EINVAL; if (nid < 0 || nid >= nr_node_ids) return -EINVAL; if (nr_to_scan == 0) return size; if (shrinker->flags & SHRINKER_MEMCG_AWARE) { memcg = mem_cgroup_get_from_ino(ino); if (!memcg || IS_ERR(memcg)) return -ENOENT; if (!mem_cgroup_online(memcg)) { mem_cgroup_put(memcg); return -ENOENT; } } else if (ino != 0) { return -EINVAL; } sc.nid = nid; sc.memcg = memcg; sc.nr_to_scan = nr_to_scan; sc.nr_scanned = nr_to_scan; shrinker->scan_objects(shrinker, &sc); mem_cgroup_put(memcg); return size; } static const struct file_operations shrinker_debugfs_scan_fops = { .owner = THIS_MODULE, .open = shrinker_debugfs_scan_open, .write = shrinker_debugfs_scan_write, }; int shrinker_debugfs_add(struct shrinker *shrinker) { struct dentry *entry; char buf[128]; int id; lockdep_assert_held(&shrinker_mutex); /* debugfs isn't initialized yet, add debugfs entries later. */ if (!shrinker_debugfs_root) return 0; id = ida_alloc(&shrinker_debugfs_ida, GFP_KERNEL); if (id < 0) return id; shrinker->debugfs_id = id; snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, id); /* create debugfs entry */ entry = debugfs_create_dir(buf, shrinker_debugfs_root); if (IS_ERR(entry)) { ida_free(&shrinker_debugfs_ida, id); return PTR_ERR(entry); } shrinker->debugfs_entry = entry; debugfs_create_file("count", 0440, entry, shrinker, &shrinker_debugfs_count_fops); debugfs_create_file("scan", 0220, entry, shrinker, &shrinker_debugfs_scan_fops); return 0; } int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) { struct dentry *entry; char buf[128]; const char *new, *old; va_list ap; int ret = 0; va_start(ap, fmt); new = kvasprintf_const(GFP_KERNEL, fmt, ap); va_end(ap); if (!new) return -ENOMEM; mutex_lock(&shrinker_mutex); old = shrinker->name; shrinker->name = new; if (shrinker->debugfs_entry) { snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, shrinker->debugfs_id); entry = debugfs_rename(shrinker_debugfs_root, shrinker->debugfs_entry, shrinker_debugfs_root, buf); if (IS_ERR(entry)) ret = PTR_ERR(entry); else shrinker->debugfs_entry = entry; } mutex_unlock(&shrinker_mutex); kfree_const(old); return ret; } EXPORT_SYMBOL(shrinker_debugfs_rename); struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker, int *debugfs_id) { struct dentry *entry = shrinker->debugfs_entry; lockdep_assert_held(&shrinker_mutex); *debugfs_id = entry ? shrinker->debugfs_id : -1; shrinker->debugfs_entry = NULL; return entry; } void shrinker_debugfs_remove(struct dentry *debugfs_entry, int debugfs_id) { debugfs_remove_recursive(debugfs_entry); ida_free(&shrinker_debugfs_ida, debugfs_id); } static int __init shrinker_debugfs_init(void) { struct shrinker *shrinker; struct dentry *dentry; int ret = 0; dentry = debugfs_create_dir("shrinker", NULL); if (IS_ERR(dentry)) return PTR_ERR(dentry); shrinker_debugfs_root = dentry; /* Create debugfs entries for shrinkers registered at boot */ mutex_lock(&shrinker_mutex); list_for_each_entry(shrinker, &shrinker_list, list) if (!shrinker->debugfs_entry) { ret = shrinker_debugfs_add(shrinker); if (ret) break; } mutex_unlock(&shrinker_mutex); return ret; } late_initcall(shrinker_debugfs_init);