diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 21113da2f03c..434a01acd01b 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -221,6 +221,7 @@ dump_debug_buffer(void)
 {
 	if (dump_opt['G']) {
 		(void) printf("\n");
+		(void) fflush(stdout);
 		zfs_dbgmsg_print("zdb");
 	}
 }
diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index 1ac5a342eec8..6395ab21d0be 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -179,6 +179,7 @@ typedef struct ztest_shared_opts {
 	uint64_t zo_metaslab_force_ganging;
 	int zo_mmp_test;
 	int zo_special_vdevs;
+	int zo_dump_dbgmsg;
 } ztest_shared_opts_t;
 
 static const ztest_shared_opts_t ztest_opts_defaults = {
@@ -474,7 +475,6 @@ static kmutex_t ztest_checkpoint_lock;
 static pthread_rwlock_t ztest_name_lock;
 
 static boolean_t ztest_dump_core = B_TRUE;
-static boolean_t ztest_dump_debug_buffer = B_FALSE;
 static boolean_t ztest_exiting;
 
 /* Global commit callback list */
@@ -523,10 +523,16 @@ _umem_logging_init(void)
 static void
 dump_debug_buffer(void)
 {
-	if (!ztest_dump_debug_buffer)
+	ssize_t ret __attribute__((unused));
+
+	if (!ztest_opts.zo_dump_dbgmsg)
 		return;
 
-	(void) printf("\n");
+	/*
+	 * We use write() instead of printf() so that this function
+	 * is safe to call from a signal handler.
+	 */
+	ret = write(STDOUT_FILENO, "\n", 1);
 	zfs_dbgmsg_print("ztest");
 }
 
@@ -581,10 +587,11 @@ fatal(int do_perror, char *message, ...)
 	(void) fprintf(stderr, "%s\n", buf);
 	fatal_msg = buf;			/* to ease debugging */
 
-	dump_debug_buffer();
-
 	if (ztest_dump_core)
 		abort();
+	else
+		dump_debug_buffer();
+
 	exit(3);
 }
 
@@ -856,7 +863,7 @@ process_options(int argc, char **argv)
 				usage(B_FALSE);
 			break;
 		case 'G':
-			ztest_dump_debug_buffer = B_TRUE;
+			zo->zo_dump_dbgmsg = 1;
 			break;
 		case 'h':
 			usage(B_TRUE);
diff --git a/include/sys/zfs_debug.h b/include/sys/zfs_debug.h
index f3a936ae7ba0..f60932b5a86b 100644
--- a/include/sys/zfs_debug.h
+++ b/include/sys/zfs_debug.h
@@ -55,11 +55,12 @@ extern int zfs_dbgmsg_enable;
 #define	ZFS_DEBUG_SET_ERROR		(1 << 9)
 #define	ZFS_DEBUG_INDIRECT_REMAP	(1 << 10)
 
-extern void __dprintf(const char *file, const char *func,
+extern void __zfs_dbgmsg(char *buf);
+extern void __dprintf(boolean_t dprint, const char *file, const char *func,
     int line, const char *fmt, ...);
 #define	zfs_dbgmsg(...) \
 	if (zfs_dbgmsg_enable) \
-		__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
+		__dprintf(B_FALSE, __FILE__, __func__, __LINE__, __VA_ARGS__)
 
 #ifdef ZFS_DEBUG
 /*
@@ -69,7 +70,7 @@ extern void __dprintf(const char *file, const char *func,
  */
 #define	dprintf(...) \
 	if (zfs_flags & ZFS_DEBUG_DPRINTF) \
-		__dprintf(__FILE__, __func__, __LINE__, __VA_ARGS__)
+		__dprintf(B_TRUE, __FILE__, __func__, __LINE__, __VA_ARGS__)
 #else
 #define	dprintf(...) ((void)0)
 #endif /* ZFS_DEBUG */
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index 5baf52514a7b..4fcde3df7772 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -783,7 +783,8 @@ dprintf_setup(int *argc, char **argv)
  * =========================================================================
  */
 void
-__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
+__dprintf(boolean_t dprint, const char *file, const char *func,
+    int line, const char *fmt, ...)
 {
 	const char *newfile;
 	va_list adx;
@@ -798,9 +799,14 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 		newfile = file;
 	}
 
-	if (dprintf_print_all ||
-	    dprintf_find_string(newfile) ||
-	    dprintf_find_string(func)) {
+	if (dprint) {
+		/* dprintf messages are printed immediately */
+
+		if (!dprintf_print_all &&
+		    !dprintf_find_string(newfile) &&
+		    !dprintf_find_string(func))
+			return;
+
 		/* Print out just the function name if requested */
 		flockfile(stdout);
 		if (dprintf_find_string("pid"))
@@ -813,11 +819,37 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 			(void) printf("%llu ", gethrtime());
 		if (dprintf_find_string("long"))
 			(void) printf("%s, line %d: ", newfile, line);
-		(void) printf("%s: ", func);
+		(void) printf("dprintf: %s: ", func);
 		va_start(adx, fmt);
 		(void) vprintf(fmt, adx);
 		va_end(adx);
 		funlockfile(stdout);
+	} else {
+		/* zfs_dbgmsg is logged for dumping later */
+		size_t size;
+		char *buf, *nl;
+		int i;
+
+		size = 1024;
+		buf = umem_alloc(size, UMEM_NOFAIL);
+		i = snprintf(buf, size, "%s:%d:%s(): ", newfile, line, func);
+
+		if (i < size) {
+			va_start(adx, fmt);
+			(void) vsnprintf(buf + i, size - i, fmt, adx);
+			va_end(adx);
+		}
+
+		/*
+		 * Get rid of trailing newline.
+		 */
+		nl = strrchr(buf, '\n');
+		if (nl != NULL)
+			*nl = '\0';
+
+		__zfs_dbgmsg(buf);
+
+		umem_free(buf, size);
 	}
 }
 
diff --git a/module/zfs/zfs_debug.c b/module/zfs/zfs_debug.c
index b5f93fd9bebb..e50552f6b7c9 100644
--- a/module/zfs/zfs_debug.c
+++ b/module/zfs/zfs_debug.c
@@ -124,11 +124,10 @@ __set_error(const char *file, const char *func, int line, int err)
 	 * $ echo 512 >/sys/module/zfs/parameters/zfs_flags
 	 */
 	if (zfs_flags & ZFS_DEBUG_SET_ERROR)
-		__dprintf(file, func, line, "error %lu", err);
+		__dprintf(B_FALSE, file, func, line, "error %lu", err);
 }
 
-#ifdef _KERNEL
-static void
+void
 __zfs_dbgmsg(char *buf)
 {
 	int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
@@ -144,8 +143,11 @@ __zfs_dbgmsg(char *buf)
 	mutex_exit(&zfs_dbgmsgs.pl_lock);
 }
 
+#ifdef _KERNEL
+
 void
-__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
+__dprintf(boolean_t dprint, const char *file, const char *func,
+    int line, const char *fmt, ...)
 {
 	const char *newfile;
 	va_list adx;
@@ -153,6 +155,7 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 	char *buf;
 	char *nl;
 	int i;
+	char *prefix = (dprint) ? "dprintf: " : "";
 
 	size = 1024;
 	buf = kmem_alloc(size, KM_SLEEP);
@@ -167,7 +170,7 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 		newfile = file;
 	}
 
-	i = snprintf(buf, size, "%s:%d:%s(): ", newfile, line, func);
+	i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
 
 	if (i < size) {
 		va_start(adx, fmt);
@@ -212,11 +215,24 @@ __dprintf(const char *file, const char *func, int line, const char *fmt, ...)
 void
 zfs_dbgmsg_print(const char *tag)
 {
-	(void) printf("ZFS_DBGMSG(%s):\n", tag);
+	ssize_t ret __attribute__((unused));
+
+	/*
+	 * We use write() in this function instead of printf()
+	 * so it is safe to call from a signal handler.
+	 */
+	ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
+	ret = write(STDOUT_FILENO, tag, strlen(tag));
+	ret = write(STDOUT_FILENO, "):\n", 3);
+
 	mutex_enter(&zfs_dbgmsgs.pl_lock);
 	for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
-	    zdm = list_next(&zfs_dbgmsgs.pl_list, zdm))
-		(void) printf("%s\n", zdm->zdm_msg);
+	    zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
+		ret = write(STDOUT_FILENO, zdm->zdm_msg,
+		    strlen(zdm->zdm_msg));
+		ret = write(STDOUT_FILENO, "\n", 1);
+	}
+
 	mutex_exit(&zfs_dbgmsgs.pl_lock);
 }
 #endif /* _KERNEL */