MFV r323531: 8521 nvlist memory leak in get_clones_stat() and spa_load_best()

illumos/illumos-gate@7d3000f774
7d3000f774

https://www.illumos.org/issues/8521
  Yuri reported this to the mailing list:
  doing a `reboot -d` on current illumos-gate HEAD gives the following "::
  findleaks -dv" output:
  findleaks: maximum buffers => 301061
  findleaks: actual buffers => 297587
  findleaks:
  findleaks: potential pointers => 29289774
  findleaks: dismissals => 26242305 (89.5%)
  findleaks: misses => 331153 ( 1.1%)
  findleaks: dups => 2419681 ( 8.2%)
  findleaks: follows => 296635 ( 1.0%)
  findleaks:
  findleaks: peak memory usage => 7353 kB
  findleaks: elapsed CPU time => 1.5 seconds
  findleaks: elapsed wall time => 2.0 seconds
  findleaks:
  CACHE LEAKED BUFCTL CALLER
  ffffff03d222b008 120 ffffff03ef7ceb78 nv_alloc_sys+0x1f
  ffffff03d222a448 123 ffffff03f4150cc8 nv_alloc_sys+0x1f
  ffffff03d222b448 5 ffffff03f28bd598 nv_alloc_sys+0x1f
  ffffff03d222b888 87 ffffff03f28c10f0 nv_alloc_sys+0x1f
  ffffff03d222c008 21 ffffff03f4139310 nv_alloc_sys+0x1f
  ffffff03d222b888 43 ffffff040ef3f3e8 nv_alloc_sys+0x1f
  ffffff03d222c008 120 ffffff03f4591e58 nv_alloc_sys+0x1f
  ffffff03d222b008 121 ffffff03f352c068 nv_alloc_sys+0x1f
  ffffff03d222a448 112 ffffff03f414e5f8 nv_alloc_sys+0x1f
  ffffff03d222b008 119 ffffff03ee92fdc0 nv_alloc_sys+0x1f
  ffffff03d222b888 46 ffffff03f28c1378 nv_alloc_sys+0x1f
  ffffff03d222b448 4 ffffff03f28c7708 nv_alloc_sys+0x1f
  ffffff03d222c008 20 ffffff03f2a6e7e8 nv_alloc_sys+0x1f

Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Yuri Pankov <yuripv@gmx.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>
Author: Pavel Zakharov <pavel.zakharov@delphix.com>

MFC after:	5 weeks
X-MFC after:	r324163

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c

@@ -1808,10 +1808,10 @@ get_clones_stat(dsl_dataset_t *ds, nvlist_t *nv)
 		fnvlist_add_nvlist(propval, ZPROP_VALUE, val);
 		fnvlist_add_nvlist(nv, zfs_prop_to_name(ZFS_PROP_CLONES),
 		    propval);
-	} else {
-		nvlist_free(val);
-		nvlist_free(propval);
 	}
+
+	nvlist_free(val);
+	nvlist_free(propval);
 }
 
 /*

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c

@@ -3096,6 +3096,8 @@ spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
 
 	if (config && (rewind_error || state != SPA_LOAD_RECOVER))
 		spa_config_set(spa, config);
+	else
+		nvlist_free(config);
 
 	if (state == SPA_LOAD_RECOVER) {
 		ASSERT3P(loadinfo, ==, NULL);

sys/kern/kern_linker.c

@@ -288,7 +288,7 @@ linker_file_sysuninit(linker_file_t lf)
 }
 
 static void
-linker_file_register_sysctls(linker_file_t lf)
+linker_file_register_sysctls(linker_file_t lf, bool enable)
 {
 	struct sysctl_oid **start, **stop, **oidp;
 
@@ -298,13 +298,39 @@ linker_file_register_sysctls(linker_file_t lf)
 
 	sx_assert(&kld_sx, SA_XLOCKED);
 
+	if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
+		return;
+
+	sx_xunlock(&kld_sx);
+	sysctl_wlock();
+	for (oidp = start; oidp < stop; oidp++) {
+		if (enable)
+			sysctl_register_oid(*oidp);
+		else
+			sysctl_register_disabled_oid(*oidp);
+	}
+	sysctl_wunlock();
+	sx_xlock(&kld_sx);
+}
+
+static void
+linker_file_enable_sysctls(linker_file_t lf)
+{
+	struct sysctl_oid **start, **stop, **oidp;
+
+	KLD_DPF(FILE,
+	    ("linker_file_enable_sysctls: enable SYSCTLs for %s\n",
+	    lf->filename));
+
+	sx_assert(&kld_sx, SA_XLOCKED);
+
 	if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
 		return;
 
 	sx_xunlock(&kld_sx);
 	sysctl_wlock();
 	for (oidp = start; oidp < stop; oidp++)
-		sysctl_register_oid(*oidp);
+		sysctl_enable_oid(*oidp);
 	sysctl_wunlock();
 	sx_xlock(&kld_sx);
 }
@@ -430,8 +456,9 @@ linker_load_file(const char *filename, linker_file_t *result)
 				return (error);
 			}
 			modules = !TAILQ_EMPTY(&lf->modules);
-			linker_file_register_sysctls(lf);
+			linker_file_register_sysctls(lf, false);
 			linker_file_sysinit(lf);
+			linker_file_enable_sysctls(lf);
 			lf->flags |= LINKER_FILE_LINKED;
 
 			/*
@@ -692,8 +719,8 @@ linker_file_unload(linker_file_t file, int flags)
 	 */
 	if (file->flags & LINKER_FILE_LINKED) {
 		file->flags &= ~LINKER_FILE_LINKED;
-		linker_file_sysuninit(file);
 		linker_file_unregister_sysctls(file);
+		linker_file_sysuninit(file);
 	}
 	TAILQ_REMOVE(&linker_files, file, link);
 
@@ -1642,7 +1669,7 @@ linker_preload(void *arg)
 		if (linker_file_lookup_set(lf, "sysinit_set", &si_start,
 		    &si_stop, NULL) == 0)
 			sysinit_add(si_start, si_stop);
-		linker_file_register_sysctls(lf);
+		linker_file_register_sysctls(lf, true);
 		lf->flags |= LINKER_FILE_LINKED;
 		continue;
 fail:

sys/kern/kern_sysctl.c

@@ -408,8 +408,8 @@ SYSCTL_PROC(_sysctl, 0, reuse_test, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
 	0, 0, sysctl_reuse_test, "-", "");
 #endif
 
-void
-sysctl_register_oid(struct sysctl_oid *oidp)
+static void
+sysctl_register_oid_impl(struct sysctl_oid *oidp, bool enable)
 {
 	struct sysctl_oid_list *parent = oidp->oid_parent;
 	struct sysctl_oid *p;
@@ -491,6 +491,17 @@ sysctl_register_oid(struct sysctl_oid *oidp)
 	}
 	/* update the OID number, if any */
 	oidp->oid_number = oid_number;
+
+	/*
+	 * Mark the leaf as dormant if it's not to be immediately enabled.
+	 * We do not disable nodes as they can be shared between modules
+	 * and it is always safe to access a node.
+	 */
+	if (!enable && (oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) {
+		KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
+		    ("internal flag is set in oid_kind"));
+		oidp->oid_kind |= CTLFLAG_DORMANT;
+	}
 	if (q != NULL)
 		SLIST_INSERT_AFTER(q, oidp, oid_link);
 	else
@@ -509,6 +520,35 @@ sysctl_register_oid(struct sysctl_oid *oidp)
 	}
 }
 
+void
+sysctl_register_oid(struct sysctl_oid *oidp)
+{
+
+	sysctl_register_oid_impl(oidp, true);
+}
+
+void
+sysctl_register_disabled_oid(struct sysctl_oid *oidp)
+{
+
+	sysctl_register_oid_impl(oidp, false);
+}
+
+void
+sysctl_enable_oid(struct sysctl_oid *oidp)
+{
+
+	SYSCTL_ASSERT_WLOCKED();
+	if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
+		KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
+		    ("sysctl node is marked as dormant"));
+		return;
+	}
+	KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) != 0,
+	    ("enabling already enabled sysctl oid"));
+	oidp->oid_kind &= ~CTLFLAG_DORMANT;
+}
+
 void
 sysctl_unregister_oid(struct sysctl_oid *oidp)
 {
@@ -1057,7 +1097,7 @@ sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen,
 		*next = oidp->oid_number;
 		*oidpp = oidp;
 
-		if (oidp->oid_kind & CTLFLAG_SKIP)
+		if ((oidp->oid_kind & (CTLFLAG_SKIP | CTLFLAG_DORMANT)) != 0)
 			continue;
 
 		if (!namelen) {
@@ -1878,6 +1918,8 @@ sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
 			}
 			lsp = SYSCTL_CHILDREN(oid);
 		} else if (indx == namelen) {
+			if ((oid->oid_kind & CTLFLAG_DORMANT) != 0)
+				return (ENOENT);
 			*noid = oid;
 			if (nindx != NULL)
 				*nindx = indx;

sys/sys/sysctl.h

@@ -83,6 +83,7 @@ struct ctlname {
 #define	CTLFLAG_RD	0x80000000	/* Allow reads of variable */
 #define	CTLFLAG_WR	0x40000000	/* Allow writes to the variable */
 #define	CTLFLAG_RW	(CTLFLAG_RD|CTLFLAG_WR)
+#define	CTLFLAG_DORMANT	0x20000000	/* This sysctl is not active yet */
 #define	CTLFLAG_ANYBODY	0x10000000	/* All users can set this var */
 #define	CTLFLAG_SECURE	0x08000000	/* Permit set only if securelevel<=0 */
 #define	CTLFLAG_PRISON	0x04000000	/* Prisoned roots can fiddle */
@@ -219,6 +220,8 @@ int sysctl_dpcpu_quad(SYSCTL_HANDLER_ARGS);
  * These functions are used to add/remove an oid from the mib.
  */
 void sysctl_register_oid(struct sysctl_oid *oidp);
+void sysctl_register_disabled_oid(struct sysctl_oid *oidp);
+void sysctl_enable_oid(struct sysctl_oid *oidp);
 void sysctl_unregister_oid(struct sysctl_oid *oidp);
 
 /* Declare a static oid to allow child oids to be added to it. */