shm: trace the amount of locked segment per user

kernel/include/shm.h

@@ -47,11 +47,14 @@ enum {
 	SHM_INFO	= 14,
 };
 
+struct shmlock_user;
+
 struct shmobj {
 	struct memobj		memobj;		/* must be first */
 	int			index;
 	int			pgshift;
 	size_t			real_segsz;
+	struct shmlock_user *	user;
 	struct shmid_ds		ds;
 	struct list_head	page_list;
 	struct list_head	chain;		/* shmobj_list */
@@ -76,9 +79,33 @@ struct shm_info {
 	uint64_t	swap_successes;
 };
 
+struct shmlock_user {
+	uid_t ruid;
+	int padding;
+	size_t locked;
+
+	struct list_head chain;
+};
+
+extern ihk_spinlock_t shmlock_users_lock_body;
+
+static inline void shmlock_users_lock(void)
+{
+	ihk_mc_spinlock_lock_noirq(&shmlock_users_lock_body);
+	return;
+}
+
+static inline void shmlock_users_unlock(void)
+{
+	ihk_mc_spinlock_unlock_noirq(&shmlock_users_lock_body);
+	return;
+}
+
 void shmobj_list_lock(void);
 void shmobj_list_unlock(void);
 int shmobj_create_indexed(struct shmid_ds *ds, struct shmobj **objp);
 void shmobj_destroy(struct shmobj *obj);
+void shmlock_user_free(struct shmlock_user *user);
+int shmlock_user_get(uid_t ruid, struct shmlock_user **userp);
 
 #endif /* HEADER_SHM_H */

kernel/shmobj.c

@@ -112,6 +112,43 @@ void shmobj_list_unlock(void)
 	return;
 }
 
+/***********************************************************************
+ * shmlock_users
+ */
+ihk_spinlock_t shmlock_users_lock_body = SPIN_LOCK_UNLOCKED;
+static LIST_HEAD(shmlock_users);
+
+void shmlock_user_free(struct shmlock_user *user)
+{
+	if (user->locked) {
+		panic("shmlock_user_free()");
+	}
+	list_del(&user->chain);
+	kfree(user);
+}
+
+int shmlock_user_get(uid_t ruid, struct shmlock_user **userp)
+{
+	struct shmlock_user *user;
+
+	list_for_each_entry(user, &shmlock_users, chain) {
+		if (user->ruid == ruid) {
+			break;
+		}
+	}
+	if (&user->chain == &shmlock_users) {
+		user = kmalloc(sizeof(*user), IHK_MC_AP_NOWAIT);
+		if (!user) {
+			return -ENOMEM;
+		}
+		user->ruid = ruid;
+		user->locked = 0;
+		list_add(&user->chain, &shmlock_users);
+	}
+	*userp = user;
+	return 0;
+}
+
 /***********************************************************************
  * operations
  */
@@ -172,8 +209,21 @@ void shmobj_destroy(struct shmobj *obj)
 	extern struct shm_info the_shm_info;
 	extern struct list_head kds_free_list;
 	extern int the_maxi;
+	struct shmlock_user *user;
+	size_t size;
 
 	dkprintf("shmobj_destroy(%p [%d %o])\n", obj, obj->index, obj->ds.shm_perm.mode);
+	if (obj->user) {
+		user = obj->user;
+		obj->user = NULL;
+		shmlock_users_lock();
+		size = (obj->ds.shm_segsz + PAGE_SIZE - 1) & PAGE_MASK;
+		user->locked -= size;
+		if (!user->locked) {
+			shmlock_user_free(user);
+		}
+		shmlock_users_unlock();
+	}
 	/* zap page_list */
 	for (;;) {
 		struct page *page;

kernel/syscall.c

@@ -3783,6 +3783,9 @@ SYSCALL_DECLARE(shmctl)
 	int req;
 	int maxi;
 	struct shmobj *obj;
+	size_t size;
+	struct shmlock_user *user;
+	uid_t ruid = proc->ruid;
 
 	dkprintf("shmctl(%#x,%d,%p)\n", shmid, cmd, buf);
 	if (0) ;
@@ -3909,7 +3912,21 @@ SYSCALL_DECLARE(shmctl)
 			dkprintf("shmctl(%#x,%d,%p): lookup: %d\n", shmid, cmd, buf, error);
 			return error;
 		}
-		obj->ds.shm_perm.mode |= SHM_LOCKED;
+		if (!(obj->ds.shm_perm.mode & SHM_LOCKED)) {
+			shmlock_users_lock();
+			error = shmlock_user_get(ruid, &user);
+			if (error) {
+				shmlock_users_unlock();
+				shmobj_list_unlock();
+				ekprintf("shmctl(%#x,%d,%p): user lookup: %d\n", shmid, cmd, buf, error);
+				return -ENOMEM;
+			}
+			size = (obj->ds.shm_segsz + PAGE_SIZE - 1) & PAGE_MASK;
+			obj->ds.shm_perm.mode |= SHM_LOCKED;
+			obj->user = user;
+			user->locked += size;
+			shmlock_users_unlock();
+		}
 		shmobj_list_unlock();
 
 		dkprintf("shmctl(%#x,%d,%p): 0\n", shmid, cmd, buf);
@@ -3923,7 +3940,18 @@ SYSCALL_DECLARE(shmctl)
 			dkprintf("shmctl(%#x,%d,%p): lookup: %d\n", shmid, cmd, buf, error);
 			return error;
 		}
-		obj->ds.shm_perm.mode &= ~SHM_LOCKED;
+		if (obj->ds.shm_perm.mode & SHM_LOCKED) {
+			size = (obj->ds.shm_segsz + PAGE_SIZE - 1) & PAGE_MASK;
+			shmlock_users_lock();
+			user = obj->user;
+			obj->user = NULL;
+			user->locked -= size;
+			if (!user->locked) {
+				shmlock_user_free(user);
+			}
+			shmlock_users_unlock();
+			obj->ds.shm_perm.mode &= ~SHM_LOCKED;
+		}
 		shmobj_list_unlock();
 		dkprintf("shmctl(%#x,%d,%p): 0\n", shmid, cmd, buf);
 		return 0;