Merge branch 'akpm' (patches from Andrew)

Merge even more updates from Andrew Morton:

 - a few leftovers

 - fault-injector rework

 - add a module loader test driver

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  kmod: throttle kmod thread limit
  kmod: add test driver to stress test the module loader
  MAINTAINERS: give kmod some maintainer love
  xtensa: use generic fb.h
  fault-inject: add /proc/<pid>/fail-nth
  fault-inject: simplify access check for fail-nth
  fault-inject: make fail-nth read/write interface symmetric
  fault-inject: parse as natural 1-based value for fail-nth write interface
  fault-inject: automatically detect the number base for fail-nth write interface
  kernel/watchdog.c: use better pr_fmt prefix
  MAINTAINERS: move the befs tree to kernel.org
  lib/atomic64_test.c: add a test that atomic64_inc_not_zero() returns an int
  mm: fix overflow check in expand_upwards()

Documentation/fault-injection/fault-injection.txt

@@ -136,12 +136,13 @@ use the boot option:
 
 o proc entries
 
-- /proc/self/task/<current-tid>/fail-nth:
+- /proc/<pid>/fail-nth:
+- /proc/self/task/<tid>/fail-nth:
 
-	Write to this file of integer N makes N-th call in the current task fail
-	(N is 0-based). Read from this file returns a single char 'Y' or 'N'
-	that says if the fault setup with a previous write to this file was
-	injected or not, and disables the fault if it wasn't yet injected.
+	Write to this file of integer N makes N-th call in the task fail.
+	Read from this file returns a integer value. A value of '0' indicates
+	that the fault setup with a previous write to this file was injected.
+	A positive integer N indicates that the fault wasn't yet injected.
 	Note that this file enables all types of faults (slab, futex, etc).
 	This setting takes precedence over all other generic debugfs settings
 	like probability, interval, times, etc. But per-capability settings
@@ -320,18 +321,19 @@ int main()
 	system("echo N > /sys/kernel/debug/failslab/ignore-gfp-wait");
 	sprintf(buf, "/proc/self/task/%ld/fail-nth", syscall(SYS_gettid));
 	fail_nth = open(buf, O_RDWR);
-	for (i = 0;; i++) {
+	for (i = 1;; i++) {
 		sprintf(buf, "%d", i);
 		write(fail_nth, buf, strlen(buf));
 		res = socketpair(AF_LOCAL, SOCK_STREAM, 0, fds);
 		err = errno;
-		read(fail_nth, buf, 1);
+		pread(fail_nth, buf, sizeof(buf), 0);
 		if (res == 0) {
 			close(fds[0]);
 			close(fds[1]);
 		}
-		printf("%d-th fault %c: res=%d/%d\n", i, buf[0], res, err);
-		if (buf[0] != 'Y')
+		printf("%d-th fault %c: res=%d/%d\n", i, atoi(buf) ? 'N' : 'Y',
+			res, err);
+		if (atoi(buf))
 			break;
 	}
 	return 0;
@@ -339,7 +341,6 @@ int main()
 
 An example output:
 
-0-th fault Y: res=-1/23
 1-th fault Y: res=-1/23
 2-th fault Y: res=-1/23
 3-th fault Y: res=-1/12

MAINTAINERS

@@ -2516,10 +2516,10 @@ S:	Supported
 F:	drivers/media/platform/sti/delta
 
 BEFS FILE SYSTEM
-M:	Luis de Bethencourt <luisbg@osg.samsung.com>
+M:	Luis de Bethencourt <luisbg@kernel.org>
 M:	Salah Triki <salah.triki@gmail.com>
 S:	Maintained
-T:	git git://github.com/luisbg/linux-befs.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/luisbg/linux-befs.git
 F:	Documentation/filesystems/befs.txt
 F:	fs/befs/
 
@@ -7554,6 +7554,15 @@ F:	include/linux/kmemleak.h
 F:	mm/kmemleak.c
 F:	mm/kmemleak-test.c
 
+KMOD MODULE USERMODE HELPER
+M:	"Luis R. Rodriguez" <mcgrof@kernel.org>
+L:	linux-kernel@vger.kernel.org
+S:	Maintained
+F:	kernel/kmod.c
+F:	include/linux/kmod.h
+F:	lib/test_kmod.c
+F:	tools/testing/selftests/kmod/
+
 KPROBES
 M:	Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
 M:	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>

arch/xtensa/include/asm/Kbuild

@@ -5,6 +5,7 @@ generic-y += dma-contiguous.h
 generic-y += emergency-restart.h
 generic-y += exec.h
 generic-y += extable.h
+generic-y += fb.h
 generic-y += hardirq.h
 generic-y += irq_regs.h
 generic-y += irq_work.h

arch/xtensa/include/asm/fb.h

-#ifndef _ASM_FB_H_
-#define _ASM_FB_H_
-#include <linux/fb.h>
-
-#define fb_pgprotect(...) do {} while (0)
-
-static inline int fb_is_primary_device(struct fb_info *info)
-{
-	return 0;
-}
-
-#endif /* _ASM_FB_H_ */

fs/proc/base.c

@@ -1360,20 +1360,19 @@ static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf,
 				   size_t count, loff_t *ppos)
 {
 	struct task_struct *task;
-	int err, n;
+	int err;
+	unsigned int n;
+
+	err = kstrtouint_from_user(buf, count, 0, &n);
+	if (err)
+		return err;
 
 	task = get_proc_task(file_inode(file));
 	if (!task)
 		return -ESRCH;
+	WRITE_ONCE(task->fail_nth, n);
 	put_task_struct(task);
-	if (task != current)
-		return -EPERM;
-	err = kstrtoint_from_user(buf, count, 10, &n);
-	if (err)
-		return err;
-	if (n < 0 || n == INT_MAX)
-		return -EINVAL;
-	current->fail_nth = n + 1;
+
 	return count;
 }
 
@@ -1381,21 +1380,18 @@ static ssize_t proc_fail_nth_read(struct file *file, char __user *buf,
 				  size_t count, loff_t *ppos)
 {
 	struct task_struct *task;
-	int err;
+	char numbuf[PROC_NUMBUF];
+	ssize_t len;
 
 	task = get_proc_task(file_inode(file));
 	if (!task)
 		return -ESRCH;
+	len = snprintf(numbuf, sizeof(numbuf), "%u\n",
+			READ_ONCE(task->fail_nth));
+	len = simple_read_from_buffer(buf, count, ppos, numbuf, len);
 	put_task_struct(task);
-	if (task != current)
-		return -EPERM;
-	if (count < 1)
-		return -EINVAL;
-	err = put_user((char)(current->fail_nth ? 'N' : 'Y'), buf);
-	if (err)
-		return err;
-	current->fail_nth = 0;
-	return 1;
+
+	return len;
 }
 
 static const struct file_operations proc_fail_nth_operations = {
@@ -2966,6 +2962,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 #endif
 #ifdef CONFIG_FAULT_INJECTION
 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
+	REG("fail-nth", 0644, proc_fail_nth_operations),
 #endif
 #ifdef CONFIG_ELF_CORE
 	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
@@ -3358,11 +3355,7 @@ static const struct pid_entry tid_base_stuff[] = {
 #endif
 #ifdef CONFIG_FAULT_INJECTION
 	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
-	/*
-	 * Operations on the file check that the task is current,
-	 * so we create it with 0666 to support testing under unprivileged user.
-	 */
-	REG("fail-nth", 0666, proc_fail_nth_operations),
+	REG("fail-nth", 0644, proc_fail_nth_operations),
 #endif
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 	ONE("io",	S_IRUSR, proc_tid_io_accounting),

include/linux/sched.h

@@ -974,7 +974,7 @@ struct task_struct {
 
 #ifdef CONFIG_FAULT_INJECTION
 	int				make_it_fail;
-	int fail_nth;
+	unsigned int			fail_nth;
 #endif
 	/*
 	 * When (nr_dirtied >= nr_dirtied_pause), it's time to call

kernel/kmod.c

@@ -68,6 +68,7 @@ static DECLARE_RWSEM(umhelper_sem);
  */
 #define MAX_KMOD_CONCURRENT 50
 static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT);
+static DECLARE_WAIT_QUEUE_HEAD(kmod_wq);
 
 /*
 	modprobe_path is set via /proc/sys.
@@ -140,7 +141,6 @@ int __request_module(bool wait, const char *fmt, ...)
 	va_list args;
 	char module_name[MODULE_NAME_LEN];
 	int ret;
-	static int kmod_loop_msg;
 
 	/*
 	 * We don't allow synchronous module loading from async.  Module
@@ -164,14 +164,11 @@ int __request_module(bool wait, const char *fmt, ...)
 		return ret;
 
 	if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) {
-		/* We may be blaming an innocent here, but unlikely */
-		if (kmod_loop_msg < 5) {
-			printk(KERN_ERR
-			       "request_module: runaway loop modprobe %s\n",
-			       module_name);
-			kmod_loop_msg++;
-		}
-		return -ENOMEM;
+		pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...",
+				    atomic_read(&kmod_concurrent_max),
+				    MAX_KMOD_CONCURRENT, module_name);
+		wait_event_interruptible(kmod_wq,
+					 atomic_dec_if_positive(&kmod_concurrent_max) >= 0);
 	}
 
 	trace_module_request(module_name, wait, _RET_IP_);
@@ -179,6 +176,7 @@ int __request_module(bool wait, const char *fmt, ...)
 	ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 
 	atomic_inc(&kmod_concurrent_max);
+	wake_up(&kmod_wq);
 
 	return ret;
 }

kernel/watchdog.c

@@ -9,7 +9,7 @@
  * to those contributors as well.
  */
 
-#define pr_fmt(fmt) "NMI watchdog: " fmt
+#define pr_fmt(fmt) "watchdog: " fmt
 
 #include <linux/mm.h>
 #include <linux/cpu.h>

lib/Kconfig.debug

@@ -1847,6 +1847,33 @@ config BUG_ON_DATA_CORRUPTION
 
 	  If unsure, say N.
 
+config TEST_KMOD
+	tristate "kmod stress tester"
+	default n
+	depends on m
+	depends on BLOCK && (64BIT || LBDAF)	  # for XFS, BTRFS
+	depends on NETDEVICES && NET_CORE && INET # for TUN
+	select TEST_LKM
+	select XFS_FS
+	select TUN
+	select BTRFS_FS
+	help
+	  Test the kernel's module loading mechanism: kmod. kmod implements
+	  support to load modules using the Linux kernel's usermode helper.
+	  This test provides a series of tests against kmod.
+
+	  Although technically you can either build test_kmod as a module or
+	  into the kernel we disallow building it into the kernel since
+	  it stress tests request_module() and this will very likely cause
+	  some issues by taking over precious threads available from other
+	  module load requests, ultimately this could be fatal.
+
+	  To run tests run:
+
+	  tools/testing/selftests/kmod/kmod.sh --help
+
+	  If unsure, say N.
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"

lib/Makefile

@@ -61,6 +61,7 @@ obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
 obj-$(CONFIG_TEST_PARMAN) += test_parman.o
+obj-$(CONFIG_TEST_KMOD) += test_kmod.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG

lib/atomic64_test.c

@@ -153,8 +153,10 @@ static __init void test_atomic64(void)
 	long long v0 = 0xaaa31337c001d00dLL;
 	long long v1 = 0xdeadbeefdeafcafeLL;
 	long long v2 = 0xfaceabadf00df001LL;
+	long long v3 = 0x8000000000000000LL;
 	long long onestwos = 0x1111111122222222LL;
 	long long one = 1LL;
+	int r_int;
 
 	atomic64_t v = ATOMIC64_INIT(v0);
 	long long r = v0;
@@ -240,6 +242,11 @@ static __init void test_atomic64(void)
 	BUG_ON(!atomic64_inc_not_zero(&v));
 	r += one;
 	BUG_ON(v.counter != r);
+
+	/* Confirm the return value fits in an int, even if the value doesn't */
+	INIT(v3);
+	r_int = atomic64_inc_not_zero(&v);
+	BUG_ON(!r_int);
 }
 
 static __init int test_atomics_init(void)

lib/fault-inject.c

@@ -107,9 +107,12 @@ static inline bool fail_stacktrace(struct fault_attr *attr)
 
 bool should_fail(struct fault_attr *attr, ssize_t size)
 {
-	if (in_task() && current->fail_nth) {
-		if (--current->fail_nth == 0)
+	if (in_task()) {
+		unsigned int fail_nth = READ_ONCE(current->fail_nth);
+
+		if (fail_nth && !WRITE_ONCE(current->fail_nth, fail_nth - 1))
 			goto fail;
+
 		return false;
 	}
 

lib/test_kmod.c

+/*
+ * kmod stress test driver
+ *
+ * Copyright (C) 2017 Luis R. Rodriguez <mcgrof@kernel.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or at your option any
+ * later version; or, when distributed separately from the Linux kernel or
+ * when incorporated into other software packages, subject to the following
+ * license:
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of copyleft-next (version 0.3.1 or later) as published
+ * at http://copyleft-next.org/.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+/*
+ * This driver provides an interface to trigger and test the kernel's
+ * module loader through a series of configurations and a few triggers.
+ * To test this driver use the following script as root:
+ *
+ * tools/testing/selftests/kmod/kmod.sh --help
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kmod.h>
+#include <linux/printk.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+
+#define TEST_START_NUM_THREADS	50
+#define TEST_START_DRIVER	"test_module"
+#define TEST_START_TEST_FS	"xfs"
+#define TEST_START_TEST_CASE	TEST_KMOD_DRIVER
+
+
+static bool force_init_test = false;
+module_param(force_init_test, bool_enable_only, 0644);
+MODULE_PARM_DESC(force_init_test,
+		 "Force kicking a test immediately after driver loads");
+
+/*
+ * For device allocation / registration
+ */
+static DEFINE_MUTEX(reg_dev_mutex);
+static LIST_HEAD(reg_test_devs);
+
+/*
+ * num_test_devs actually represents the *next* ID of the next
+ * device we will allow to create.
+ */
+static int num_test_devs;
+
+/**
+ * enum kmod_test_case - linker table test case
+ *
+ * If you add a  test case, please be sure to review if you need to se
+ * @need_mod_put for your tests case.
+ *
+ * @TEST_KMOD_DRIVER: stress tests request_module()
+ * @TEST_KMOD_FS_TYPE: stress tests get_fs_type()
+ */
+enum kmod_test_case {
+	__TEST_KMOD_INVALID = 0,
+
+	TEST_KMOD_DRIVER,
+	TEST_KMOD_FS_TYPE,
+
+	__TEST_KMOD_MAX,
+};
+
+struct test_config {
+	char *test_driver;
+	char *test_fs;
+	unsigned int num_threads;
+	enum kmod_test_case test_case;
+	int test_result;
+};
+
+struct kmod_test_device;
+
+/**
+ * kmod_test_device_info - thread info
+ *
+ * @ret_sync: return value if request_module() is used, sync request for
+ * 	@TEST_KMOD_DRIVER
+ * @fs_sync: return value of get_fs_type() for @TEST_KMOD_FS_TYPE
+ * @thread_idx: thread ID
+ * @test_dev: test device test is being performed under
+ * @need_mod_put: Some tests (get_fs_type() is one) requires putting the module
+ *	(module_put(fs_sync->owner)) when done, otherwise you will not be able
+ *	to unload the respective modules and re-test. We use this to keep
+ *	accounting of when we need this and to help out in case we need to
+ *	error out and deal with module_put() on error.
+ */
+struct kmod_test_device_info {
+	int ret_sync;
+	struct file_system_type *fs_sync;
+	struct task_struct *task_sync;
+	unsigned int thread_idx;
+	struct kmod_test_device *test_dev;
+	bool need_mod_put;
+};
+
+/**
+ * kmod_test_device - test device to help test kmod
+ *
+ * @dev_idx: unique ID for test device
+ * @config: configuration for the test
+ * @misc_dev: we use a misc device under the hood
+ * @dev: pointer to misc_dev's own struct device
+ * @config_mutex: protects configuration of test
+ * @trigger_mutex: the test trigger can only be fired once at a time
+ * @thread_lock: protects @done count, and the @info per each thread
+ * @done: number of threads which have completed or failed
+ * @test_is_oom: when we run out of memory, use this to halt moving forward
+ * @kthreads_done: completion used to signal when all work is done
+ * @list: needed to be part of the reg_test_devs
+ * @info: array of info for each thread
+ */
+struct kmod_test_device {
+	int dev_idx;
+	struct test_config config;
+	struct miscdevice misc_dev;
+	struct device *dev;
+	struct mutex config_mutex;
+	struct mutex trigger_mutex;
+	struct mutex thread_mutex;
+
+	unsigned int done;
+
+	bool test_is_oom;
+	struct completion kthreads_done;
+	struct list_head list;
+
+	struct kmod_test_device_info *info;
+};
+
+static const char *test_case_str(enum kmod_test_case test_case)
+{
+	switch (test_case) {
+	case TEST_KMOD_DRIVER:
+		return "TEST_KMOD_DRIVER";
+	case TEST_KMOD_FS_TYPE:
+		return "TEST_KMOD_FS_TYPE";
+	default:
+		return "invalid";
+	}
+}
+
+static struct miscdevice *dev_to_misc_dev(struct device *dev)
+{
+	return dev_get_drvdata(dev);
+}
+
+static struct kmod_test_device *misc_dev_to_test_dev(struct miscdevice *misc_dev)
+{
+	return container_of(misc_dev, struct kmod_test_device, misc_dev);
+}
+
+static struct kmod_test_device *dev_to_test_dev(struct device *dev)
+{
+	struct miscdevice *misc_dev;
+
+	misc_dev = dev_to_misc_dev(dev);
+
+	return misc_dev_to_test_dev(misc_dev);
+}
+
+/* Must run with thread_mutex held */
+static void kmod_test_done_check(struct kmod_test_device *test_dev,
+				 unsigned int idx)
+{
+	struct test_config *config = &test_dev->config;
+
+	test_dev->done++;
+	dev_dbg(test_dev->dev, "Done thread count: %u\n", test_dev->done);
+
+	if (test_dev->done == config->num_threads) {
+		dev_info(test_dev->dev, "Done: %u threads have all run now\n",
+			 test_dev->done);
+		dev_info(test_dev->dev, "Last thread to run: %u\n", idx);
+		complete(&test_dev->kthreads_done);
+	}
+}
+
+static void test_kmod_put_module(struct kmod_test_device_info *info)
+{
+	struct kmod_test_device *test_dev = info->test_dev;
+	struct test_config *config = &test_dev->config;
+
+	if (!info->need_mod_put)
+		return;
+
+	switch (config->test_case) {
+	case TEST_KMOD_DRIVER:
+		break;
+	case TEST_KMOD_FS_TYPE:
+		if (info && info->fs_sync && info->fs_sync->owner)
+			module_put(info->fs_sync->owner);
+		break;
+	default:
+		BUG();
+	}
+
+	info->need_mod_put = true;
+}
+
+static int run_request(void *data)
+{
+	struct kmod_test_device_info *info = data;
+	struct kmod_test_device *test_dev = info->test_dev;
+	struct test_config *config = &test_dev->config;
+
+	switch (config->test_case) {
+	case TEST_KMOD_DRIVER:
+		info->ret_sync = request_module("%s", config->test_driver);
+		break;
+	case TEST_KMOD_FS_TYPE:
+		info->fs_sync = get_fs_type(config->test_fs);
+		info->need_mod_put = true;
+		break;
+	default:
+		/* __trigger_config_run() already checked for test sanity */
+		BUG();
+		return -EINVAL;
+	}
+
+	dev_dbg(test_dev->dev, "Ran thread %u\n", info->thread_idx);
+
+	test_kmod_put_module(info);
+
+	mutex_lock(&test_dev->thread_mutex);
+	info->task_sync = NULL;
+	kmod_test_done_check(test_dev, info->thread_idx);
+	mutex_unlock(&test_dev->thread_mutex);
+
+	return 0;
+}
+
+static int tally_work_test(struct kmod_test_device_info *info)
+{
+	struct kmod_test_device *test_dev = info->test_dev;
+	struct test_config *config = &test_dev->config;
+	int err_ret = 0;
+
+	switch (config->test_case) {
+	case TEST_KMOD_DRIVER:
+		/*
+		 * Only capture errors, if one is found that's
+		 * enough, for now.
+		 */
+		if (info->ret_sync != 0)
+			err_ret = info->ret_sync;
+		dev_info(test_dev->dev,
+			 "Sync thread %d return status: %d\n",
+			 info->thread_idx, info->ret_sync);
+		break;
+	case TEST_KMOD_FS_TYPE:
+		/* For now we make this simple */
+		if (!info->fs_sync)
+			err_ret = -EINVAL;
+		dev_info(test_dev->dev, "Sync thread %u fs: %s\n",
+			 info->thread_idx, info->fs_sync ? config->test_fs :
+			 "NULL");
+		break;
+	default:
+		BUG();
+	}
+
+	return err_ret;
+}
+
+/*
+ * XXX: add result option to display if all errors did not match.
+ * For now we just keep any error code if one was found.
+ *
+ * If this ran it means *all* tasks were created fine and we
+ * are now just collecting results.
+ *
+ * Only propagate errors, do not override with a subsequent sucess case.
+ */
+static void tally_up_work(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+	struct kmod_test_device_info *info;
+	unsigned int idx;
+	int err_ret = 0;
+	int ret = 0;
+
+	mutex_lock(&test_dev->thread_mutex);
+
+	dev_info(test_dev->dev, "Results:\n");
+
+	for (idx=0; idx < config->num_threads; idx++) {
+		info = &test_dev->info[idx];
+		ret = tally_work_test(info);
+		if (ret)
+			err_ret = ret;
+	}
+
+	/*
+	 * Note: request_module() returns 256 for a module not found even
+	 * though modprobe itself returns 1.
+	 */
+	config->test_result = err_ret;
+
+	mutex_unlock(&test_dev->thread_mutex);
+}
+
+static int try_one_request(struct kmod_test_device *test_dev, unsigned int idx)
+{
+	struct kmod_test_device_info *info = &test_dev->info[idx];
+	int fail_ret = -ENOMEM;
+
+	mutex_lock(&test_dev->thread_mutex);
+
+	info->thread_idx = idx;
+	info->test_dev = test_dev;
+	info->task_sync = kthread_run(run_request, info, "%s-%u",
+				      KBUILD_MODNAME, idx);
+
+	if (!info->task_sync || IS_ERR(info->task_sync)) {
+		test_dev->test_is_oom = true;
+		dev_err(test_dev->dev, "Setting up thread %u failed\n", idx);
+		info->task_sync = NULL;
+		goto err_out;
+	} else
+		dev_dbg(test_dev->dev, "Kicked off thread %u\n", idx);
+
+	mutex_unlock(&test_dev->thread_mutex);
+
+	return 0;
+
+err_out:
+	info->ret_sync = fail_ret;
+	mutex_unlock(&test_dev->thread_mutex);
+
+	return fail_ret;
+}
+
+static void test_dev_kmod_stop_tests(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+	struct kmod_test_device_info *info;
+	unsigned int i;
+
+	dev_info(test_dev->dev, "Ending request_module() tests\n");
+
+	mutex_lock(&test_dev->thread_mutex);
+
+	for (i=0; i < config->num_threads; i++) {
+		info = &test_dev->info[i];
+		if (info->task_sync && !IS_ERR(info->task_sync)) {
+			dev_info(test_dev->dev,
+				 "Stopping still-running thread %i\n", i);
+			kthread_stop(info->task_sync);
+		}
+
+		/*
+		 * info->task_sync is well protected, it can only be
+		 * NULL or a pointer to a struct. If its NULL we either
+		 * never ran, or we did and we completed the work. Completed
+		 * tasks *always* put the module for us. This is a sanity
+		 * check -- just in case.
+		 */
+		if (info->task_sync && info->need_mod_put)
+			test_kmod_put_module(info);
+	}
+
+	mutex_unlock(&test_dev->thread_mutex);
+}
+
+/*
+ * Only wait *iff* we did not run into any errors during all of our thread
+ * set up. If run into any issues we stop threads and just bail out with
+ * an error to the trigger. This also means we don't need any tally work
+ * for any threads which fail.
+ */
+static int try_requests(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+	unsigned int idx;
+	int ret;
+	bool any_error = false;
+
+	for (idx=0; idx < config->num_threads; idx++) {
+		if (test_dev->test_is_oom) {
+			any_error = true;
+			break;
+		}
+
+		ret = try_one_request(test_dev, idx);
+		if (ret) {
+			any_error = true;
+			break;
+		}
+	}
+
+	if (!any_error) {
+		test_dev->test_is_oom = false;
+		dev_info(test_dev->dev,
+			 "No errors were found while initializing threads\n");
+		wait_for_completion(&test_dev->kthreads_done);
+		tally_up_work(test_dev);
+	} else {
+		test_dev->test_is_oom = true;
+		dev_info(test_dev->dev,
+			 "At least one thread failed to start, stop all work\n");
+		test_dev_kmod_stop_tests(test_dev);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int run_test_driver(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+
+	dev_info(test_dev->dev, "Test case: %s (%u)\n",
+		 test_case_str(config->test_case),
+		 config->test_case);
+	dev_info(test_dev->dev, "Test driver to load: %s\n",
+		 config->test_driver);
+	dev_info(test_dev->dev, "Number of threads to run: %u\n",
+		 config->num_threads);
+	dev_info(test_dev->dev, "Thread IDs will range from 0 - %u\n",
+		 config->num_threads - 1);
+
+	return try_requests(test_dev);
+}
+
+static int run_test_fs_type(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+
+	dev_info(test_dev->dev, "Test case: %s (%u)\n",
+		 test_case_str(config->test_case),
+		 config->test_case);
+	dev_info(test_dev->dev, "Test filesystem to load: %s\n",
+		 config->test_fs);
+	dev_info(test_dev->dev, "Number of threads to run: %u\n",
+		 config->num_threads);
+	dev_info(test_dev->dev, "Thread IDs will range from 0 - %u\n",
+		 config->num_threads - 1);
+
+	return try_requests(test_dev);
+}
+
+static ssize_t config_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+	int len = 0;
+
+	mutex_lock(&test_dev->config_mutex);
+
+	len += snprintf(buf, PAGE_SIZE,
+			"Custom trigger configuration for: %s\n",
+			dev_name(dev));
+
+	len += snprintf(buf+len, PAGE_SIZE - len,
+			"Number of threads:\t%u\n",
+			config->num_threads);
+
+	len += snprintf(buf+len, PAGE_SIZE - len,
+			"Test_case:\t%s (%u)\n",
+			test_case_str(config->test_case),
+			config->test_case);
+
+	if (config->test_driver)
+		len += snprintf(buf+len, PAGE_SIZE - len,
+				"driver:\t%s\n",
+				config->test_driver);
+	else
+		len += snprintf(buf+len, PAGE_SIZE - len,
+				"driver:\tEMTPY\n");
+
+	if (config->test_fs)
+		len += snprintf(buf+len, PAGE_SIZE - len,
+				"fs:\t%s\n",
+				config->test_fs);
+	else
+		len += snprintf(buf+len, PAGE_SIZE - len,
+				"fs:\tEMTPY\n");
+
+	mutex_unlock(&test_dev->config_mutex);
+
+	return len;
+}
+static DEVICE_ATTR_RO(config);
+
+/*
+ * This ensures we don't allow kicking threads through if our configuration
+ * is faulty.
+ */
+static int __trigger_config_run(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+
+	test_dev->done = 0;
+
+	switch (config->test_case) {
+	case TEST_KMOD_DRIVER:
+		return run_test_driver(test_dev);
+	case TEST_KMOD_FS_TYPE:
+		return run_test_fs_type(test_dev);
+	default:
+		dev_warn(test_dev->dev,
+			 "Invalid test case requested: %u\n",
+			 config->test_case);
+		return -EINVAL;
+	}
+}
+
+static int trigger_config_run(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+	int ret;
+
+	mutex_lock(&test_dev->trigger_mutex);
+	mutex_lock(&test_dev->config_mutex);
+
+	ret = __trigger_config_run(test_dev);
+	if (ret < 0)
+		goto out;
+	dev_info(test_dev->dev, "General test result: %d\n",
+		 config->test_result);
+
+	/*
+	 * We must return 0 after a trigger even unless something went
+	 * wrong with the setup of the test. If the test setup went fine
+	 * then userspace must just check the result of config->test_result.
+	 * One issue with relying on the return from a call in the kernel
+	 * is if the kernel returns a possitive value using this trigger
+	 * will not return the value to userspace, it would be lost.
+	 *
+	 * By not relying on capturing the return value of tests we are using
+	 * through the trigger it also us to run tests with set -e and only
+	 * fail when something went wrong with the driver upon trigger
+	 * requests.
+	 */
+	ret = 0;
+
+out:
+	mutex_unlock(&test_dev->config_mutex);
+	mutex_unlock(&test_dev->trigger_mutex);
+
+	return ret;
+}
+
+static ssize_t
+trigger_config_store(struct device *dev,
+		     struct device_attribute *attr,
+		     const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	int ret;
+
+	if (test_dev->test_is_oom)
+		return -ENOMEM;
+
+	/* For all intents and purposes we don't care what userspace
+	 * sent this trigger, we care only that we were triggered.
+	 * We treat the return value only for caputuring issues with
+	 * the test setup. At this point all the test variables should
+	 * have been allocated so typically this should never fail.
+	 */
+	ret = trigger_config_run(test_dev);
+	if (unlikely(ret < 0))
+		goto out;
+
+	/*
+	 * Note: any return > 0 will be treated as success
+	 * and the error value will not be available to userspace.
+	 * Do not rely on trying to send to userspace a test value
+	 * return value as possitive return errors will be lost.
+	 */
+	if (WARN_ON(ret > 0))
+		return -EINVAL;
+
+	ret = count;
+out:
+	return ret;
+}
+static DEVICE_ATTR_WO(trigger_config);
+
+/*
+ * XXX: move to kstrncpy() once merged.
+ *
+ * Users should use kfree_const() when freeing these.
+ */
+static int __kstrncpy(char **dst, const char *name, size_t count, gfp_t gfp)
+{
+	*dst = kstrndup(name, count, gfp);
+	if (!*dst)
+		return -ENOSPC;
+	return count;
+}
+
+static int config_copy_test_driver_name(struct test_config *config,
+				    const char *name,
+				    size_t count)
+{
+	return __kstrncpy(&config->test_driver, name, count, GFP_KERNEL);
+}
+
+
+static int config_copy_test_fs(struct test_config *config, const char *name,
+			       size_t count)
+{
+	return __kstrncpy(&config->test_fs, name, count, GFP_KERNEL);
+}
+
+static void __kmod_config_free(struct test_config *config)
+{
+	if (!config)
+		return;
+
+	kfree_const(config->test_driver);
+	config->test_driver = NULL;
+
+	kfree_const(config->test_fs);
+	config->test_driver = NULL;
+}
+
+static void kmod_config_free(struct kmod_test_device *test_dev)
+{
+	struct test_config *config;
+
+	if (!test_dev)
+		return;
+
+	config = &test_dev->config;
+
+	mutex_lock(&test_dev->config_mutex);
+	__kmod_config_free(config);
+	mutex_unlock(&test_dev->config_mutex);
+}
+
+static ssize_t config_test_driver_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+	int copied;
+
+	mutex_lock(&test_dev->config_mutex);
+
+	kfree_const(config->test_driver);
+	config->test_driver = NULL;
+
+	copied = config_copy_test_driver_name(config, buf, count);
+	mutex_unlock(&test_dev->config_mutex);
+
+	return copied;
+}
+
+/*
+ * As per sysfs_kf_seq_show() the buf is max PAGE_SIZE.
+ */
+static ssize_t config_test_show_str(struct mutex *config_mutex,
+				    char *dst,
+				    char *src)
+{
+	int len;
+
+	mutex_lock(config_mutex);
+	len = snprintf(dst, PAGE_SIZE, "%s\n", src);
+	mutex_unlock(config_mutex);
+
+	return len;
+}
+
+static ssize_t config_test_driver_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return config_test_show_str(&test_dev->config_mutex, buf,
+				    config->test_driver);
+}
+static DEVICE_ATTR(config_test_driver, 0644, config_test_driver_show,
+		   config_test_driver_store);
+
+static ssize_t config_test_fs_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+	int copied;
+
+	mutex_lock(&test_dev->config_mutex);
+
+	kfree_const(config->test_fs);
+	config->test_fs = NULL;
+
+	copied = config_copy_test_fs(config, buf, count);
+	mutex_unlock(&test_dev->config_mutex);
+
+	return copied;
+}
+
+static ssize_t config_test_fs_show(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return config_test_show_str(&test_dev->config_mutex, buf,
+				    config->test_fs);
+}
+static DEVICE_ATTR(config_test_fs, 0644, config_test_fs_show,
+		   config_test_fs_store);
+
+static int trigger_config_run_type(struct kmod_test_device *test_dev,
+				   enum kmod_test_case test_case,
+				   const char *test_str)
+{
+	int copied = 0;
+	struct test_config *config = &test_dev->config;
+
+	mutex_lock(&test_dev->config_mutex);
+
+	switch (test_case) {
+	case TEST_KMOD_DRIVER:
+		kfree_const(config->test_driver);
+		config->test_driver = NULL;
+		copied = config_copy_test_driver_name(config, test_str,
+						      strlen(test_str));
+		break;
+	case TEST_KMOD_FS_TYPE:
+		break;
+		kfree_const(config->test_fs);
+		config->test_driver = NULL;
+		copied = config_copy_test_fs(config, test_str,
+					     strlen(test_str));
+	default:
+		mutex_unlock(&test_dev->config_mutex);
+		return -EINVAL;
+	}
+
+	config->test_case = test_case;
+
+	mutex_unlock(&test_dev->config_mutex);
+
+	if (copied <= 0 || copied != strlen(test_str)) {
+		test_dev->test_is_oom = true;
+		return -ENOMEM;
+	}
+
+	test_dev->test_is_oom = false;
+
+	return trigger_config_run(test_dev);
+}
+
+static void free_test_dev_info(struct kmod_test_device *test_dev)
+{
+	vfree(test_dev->info);
+	test_dev->info = NULL;
+}
+
+static int kmod_config_sync_info(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+
+	free_test_dev_info(test_dev);
+	test_dev->info = vzalloc(config->num_threads *
+				 sizeof(struct kmod_test_device_info));
+	if (!test_dev->info) {
+		dev_err(test_dev->dev, "Cannot alloc test_dev info\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/*
+ * Old kernels may not have this, if you want to port this code to
+ * test it on older kernels.
+ */
+#ifdef get_kmod_umh_limit
+static unsigned int kmod_init_test_thread_limit(void)
+{
+	return get_kmod_umh_limit();
+}
+#else
+static unsigned int kmod_init_test_thread_limit(void)
+{
+	return TEST_START_NUM_THREADS;
+}
+#endif
+
+static int __kmod_config_init(struct kmod_test_device *test_dev)
+{
+	struct test_config *config = &test_dev->config;
+	int ret = -ENOMEM, copied;
+
+	__kmod_config_free(config);
+
+	copied = config_copy_test_driver_name(config, TEST_START_DRIVER,
+					      strlen(TEST_START_DRIVER));
+	if (copied != strlen(TEST_START_DRIVER))
+		goto err_out;
+
+	copied = config_copy_test_fs(config, TEST_START_TEST_FS,
+				     strlen(TEST_START_TEST_FS));
+	if (copied != strlen(TEST_START_TEST_FS))
+		goto err_out;
+
+	config->num_threads = kmod_init_test_thread_limit();
+	config->test_result = 0;
+	config->test_case = TEST_START_TEST_CASE;
+
+	ret = kmod_config_sync_info(test_dev);
+	if (ret)
+		goto err_out;
+
+	test_dev->test_is_oom = false;
+
+	return 0;
+
+err_out:
+	test_dev->test_is_oom = true;
+	WARN_ON(test_dev->test_is_oom);
+
+	__kmod_config_free(config);
+
+	return ret;
+}
+
+static ssize_t reset_store(struct device *dev,
+			   struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	int ret;
+
+	mutex_lock(&test_dev->trigger_mutex);
+	mutex_lock(&test_dev->config_mutex);
+
+	ret = __kmod_config_init(test_dev);
+	if (ret < 0) {
+		ret = -ENOMEM;
+		dev_err(dev, "could not alloc settings for config trigger: %d\n",
+		       ret);
+		goto out;
+	}
+
+	dev_info(dev, "reset\n");
+	ret = count;
+
+out:
+	mutex_unlock(&test_dev->config_mutex);
+	mutex_unlock(&test_dev->trigger_mutex);
+
+	return ret;
+}
+static DEVICE_ATTR_WO(reset);
+
+static int test_dev_config_update_uint_sync(struct kmod_test_device *test_dev,
+					    const char *buf, size_t size,
+					    unsigned int *config,
+					    int (*test_sync)(struct kmod_test_device *test_dev))
+{
+	int ret;
+	long new;
+	unsigned int old_val;
+
+	ret = kstrtol(buf, 10, &new);
+	if (ret)
+		return ret;
+
+	if (new > UINT_MAX)
+		return -EINVAL;
+
+	mutex_lock(&test_dev->config_mutex);
+
+	old_val = *config;
+	*(unsigned int *)config = new;
+
+	ret = test_sync(test_dev);
+	if (ret) {
+		*(unsigned int *)config = old_val;
+
+		ret = test_sync(test_dev);
+		WARN_ON(ret);
+
+		mutex_unlock(&test_dev->config_mutex);
+		return -EINVAL;
+	}
+
+	mutex_unlock(&test_dev->config_mutex);
+	/* Always return full write size even if we didn't consume all */
+	return size;
+}
+
+static int test_dev_config_update_uint_range(struct kmod_test_device *test_dev,
+					     const char *buf, size_t size,
+					     unsigned int *config,
+					     unsigned int min,
+					     unsigned int max)
+{
+	int ret;
+	long new;
+
+	ret = kstrtol(buf, 10, &new);
+	if (ret)
+		return ret;
+
+	if (new < min || new >  max || new > UINT_MAX)
+		return -EINVAL;
+
+	mutex_lock(&test_dev->config_mutex);
+	*config = new;
+	mutex_unlock(&test_dev->config_mutex);
+
+	/* Always return full write size even if we didn't consume all */
+	return size;
+}
+
+static int test_dev_config_update_int(struct kmod_test_device *test_dev,
+				      const char *buf, size_t size,
+				      int *config)
+{
+	int ret;
+	long new;
+
+	ret = kstrtol(buf, 10, &new);
+	if (ret)
+		return ret;
+
+	if (new > INT_MAX || new < INT_MIN)
+		return -EINVAL;
+
+	mutex_lock(&test_dev->config_mutex);
+	*config = new;
+	mutex_unlock(&test_dev->config_mutex);
+	/* Always return full write size even if we didn't consume all */
+	return size;
+}
+
+static ssize_t test_dev_config_show_int(struct kmod_test_device *test_dev,
+					char *buf,
+					int config)
+{
+	int val;
+
+	mutex_lock(&test_dev->config_mutex);
+	val = config;
+	mutex_unlock(&test_dev->config_mutex);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t test_dev_config_show_uint(struct kmod_test_device *test_dev,
+					 char *buf,
+					 unsigned int config)
+{
+	unsigned int val;
+
+	mutex_lock(&test_dev->config_mutex);
+	val = config;
+	mutex_unlock(&test_dev->config_mutex);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t test_result_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_update_int(test_dev, buf, count,
+					  &config->test_result);
+}
+
+static ssize_t config_num_threads_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_update_uint_sync(test_dev, buf, count,
+						&config->num_threads,
+						kmod_config_sync_info);
+}
+
+static ssize_t config_num_threads_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_show_int(test_dev, buf, config->num_threads);
+}
+static DEVICE_ATTR(config_num_threads, 0644, config_num_threads_show,
+		   config_num_threads_store);
+
+static ssize_t config_test_case_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_update_uint_range(test_dev, buf, count,
+						 &config->test_case,
+						 __TEST_KMOD_INVALID + 1,
+						 __TEST_KMOD_MAX - 1);
+}
+
+static ssize_t config_test_case_show(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_show_uint(test_dev, buf, config->test_case);
+}
+static DEVICE_ATTR(config_test_case, 0644, config_test_case_show,
+		   config_test_case_store);
+
+static ssize_t test_result_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct kmod_test_device *test_dev = dev_to_test_dev(dev);
+	struct test_config *config = &test_dev->config;
+
+	return test_dev_config_show_int(test_dev, buf, config->test_result);
+}
+static DEVICE_ATTR(test_result, 0644, test_result_show, test_result_store);
+
+#define TEST_KMOD_DEV_ATTR(name)		&dev_attr_##name.attr
+
+static struct attribute *test_dev_attrs[] = {
+	TEST_KMOD_DEV_ATTR(trigger_config),
+	TEST_KMOD_DEV_ATTR(config),
+	TEST_KMOD_DEV_ATTR(reset),
+
+	TEST_KMOD_DEV_ATTR(config_test_driver),
+	TEST_KMOD_DEV_ATTR(config_test_fs),
+	TEST_KMOD_DEV_ATTR(config_num_threads),
+	TEST_KMOD_DEV_ATTR(config_test_case),
+	TEST_KMOD_DEV_ATTR(test_result),
+
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(test_dev);
+
+static int kmod_config_init(struct kmod_test_device *test_dev)
+{
+	int ret;
+
+	mutex_lock(&test_dev->config_mutex);
+	ret = __kmod_config_init(test_dev);
+	mutex_unlock(&test_dev->config_mutex);
+
+	return ret;
+}
+
+static struct kmod_test_device *alloc_test_dev_kmod(int idx)
+{
+	int ret;
+	struct kmod_test_device *test_dev;
+	struct miscdevice *misc_dev;
+
+	test_dev = vzalloc(sizeof(struct kmod_test_device));
+	if (!test_dev) {
+		pr_err("Cannot alloc test_dev\n");
+		goto err_out;
+	}
+
+	mutex_init(&test_dev->config_mutex);
+	mutex_init(&test_dev->trigger_mutex);
+	mutex_init(&test_dev->thread_mutex);
+
+	init_completion(&test_dev->kthreads_done);
+
+	ret = kmod_config_init(test_dev);
+	if (ret < 0) {
+		pr_err("Cannot alloc kmod_config_init()\n");
+		goto err_out_free;
+	}
+
+	test_dev->dev_idx = idx;
+	misc_dev = &test_dev->misc_dev;
+
+	misc_dev->minor = MISC_DYNAMIC_MINOR;
+	misc_dev->name = kasprintf(GFP_KERNEL, "test_kmod%d", idx);
+	if (!misc_dev->name) {
+		pr_err("Cannot alloc misc_dev->name\n");
+		goto err_out_free_config;
+	}
+	misc_dev->groups = test_dev_groups;
+
+	return test_dev;
+
+err_out_free_config:
+	free_test_dev_info(test_dev);
+	kmod_config_free(test_dev);
+err_out_free:
+	vfree(test_dev);
+	test_dev = NULL;
+err_out:
+	return NULL;
+}
+
+static void free_test_dev_kmod(struct kmod_test_device *test_dev)
+{
+	if (test_dev) {
+		kfree_const(test_dev->misc_dev.name);
+		test_dev->misc_dev.name = NULL;
+		free_test_dev_info(test_dev);
+		kmod_config_free(test_dev);
+		vfree(test_dev);
+		test_dev = NULL;
+	}
+}
+
+static struct kmod_test_device *register_test_dev_kmod(void)
+{
+	struct kmod_test_device *test_dev = NULL;
+	int ret;
+
+	mutex_unlock(&reg_dev_mutex);
+
+	/* int should suffice for number of devices, test for wrap */
+	if (unlikely(num_test_devs + 1) < 0) {
+		pr_err("reached limit of number of test devices\n");
+		goto out;
+	}
+
+	test_dev = alloc_test_dev_kmod(num_test_devs);
+	if (!test_dev)
+		goto out;
+
+	ret = misc_register(&test_dev->misc_dev);
+	if (ret) {
+		pr_err("could not register misc device: %d\n", ret);
+		free_test_dev_kmod(test_dev);
+		goto out;
+	}
+
+	test_dev->dev = test_dev->misc_dev.this_device;
+	list_add_tail(&test_dev->list, &reg_test_devs);
+	dev_info(test_dev->dev, "interface ready\n");
+
+	num_test_devs++;
+
+out:
+	mutex_unlock(&reg_dev_mutex);
+
+	return test_dev;
+
+}
+
+static int __init test_kmod_init(void)
+{
+	struct kmod_test_device *test_dev;
+	int ret;
+
+	test_dev = register_test_dev_kmod();
+	if (!test_dev) {
+		pr_err("Cannot add first test kmod device\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * With some work we might be able to gracefully enable
+	 * testing with this driver built-in, for now this seems
+	 * rather risky. For those willing to try have at it,
+	 * and enable the below. Good luck! If that works, try
+	 * lowering the init level for more fun.
+	 */
+	if (force_init_test) {
+		ret = trigger_config_run_type(test_dev,
+					      TEST_KMOD_DRIVER, "tun");
+		if (WARN_ON(ret))
+			return ret;
+		ret = trigger_config_run_type(test_dev,
+					      TEST_KMOD_FS_TYPE, "btrfs");
+		if (WARN_ON(ret))
+			return ret;
+	}
+
+	return 0;
+}
+late_initcall(test_kmod_init);
+
+static
+void unregister_test_dev_kmod(struct kmod_test_device *test_dev)
+{
+	mutex_lock(&test_dev->trigger_mutex);
+	mutex_lock(&test_dev->config_mutex);
+
+	test_dev_kmod_stop_tests(test_dev);
+
+	dev_info(test_dev->dev, "removing interface\n");
+	misc_deregister(&test_dev->misc_dev);
+	kfree(&test_dev->misc_dev.name);
+
+	mutex_unlock(&test_dev->config_mutex);
+	mutex_unlock(&test_dev->trigger_mutex);
+
+	free_test_dev_kmod(test_dev);
+}
+
+static void __exit test_kmod_exit(void)
+{
+	struct kmod_test_device *test_dev, *tmp;
+
+	mutex_lock(&reg_dev_mutex);
+	list_for_each_entry_safe(test_dev, tmp, &reg_test_devs, list) {
+		list_del(&test_dev->list);
+		unregister_test_dev_kmod(test_dev);
+	}
+	mutex_unlock(&reg_dev_mutex);
+}
+module_exit(test_kmod_exit);
+
+MODULE_AUTHOR("Luis R. Rodriguez <mcgrof@kernel.org>");
+MODULE_LICENSE("GPL");

mm/mmap.c

@@ -2231,7 +2231,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 
 	/* Guard against exceeding limits of the address space. */
 	address &= PAGE_MASK;
-	if (address >= TASK_SIZE)
+	if (address >= (TASK_SIZE & PAGE_MASK))
 		return -ENOMEM;
 	address += PAGE_SIZE;
 

tools/testing/selftests/kmod/Makefile

+# Makefile for kmod loading selftests
+
+# No binaries, but make sure arg-less "make" doesn't trigger "run_tests"
+all:
+
+TEST_PROGS := kmod.sh
+
+include ../lib.mk
+
+# Nothing to clean up.
+clean:

tools/testing/selftests/kmod/config

+CONFIG_TEST_KMOD=m
+CONFIG_TEST_LKM=m
+CONFIG_XFS_FS=m
+
+# For the module parameter force_init_test is used
+CONFIG_TUN=m
+CONFIG_BTRFS_FS=m

tools/testing/selftests/kmod/kmod.sh

+#!/bin/bash
+#
+# Copyright (C) 2017 Luis R. Rodriguez <mcgrof@kernel.org>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or at your option any
+# later version; or, when distributed separately from the Linux kernel or
+# when incorporated into other software packages, subject to the following
+# license:
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of copyleft-next (version 0.3.1 or later) as published
+# at http://copyleft-next.org/.
+
+# This is a stress test script for kmod, the kernel module loader. It uses
+# test_kmod which exposes a series of knobs for the API for us so we can
+# tweak each test in userspace rather than in kernelspace.
+#
+# The way kmod works is it uses the kernel's usermode helper API to eventually
+# call /sbin/modprobe. It has a limit of the number of concurrent calls
+# possible. The kernel interface to load modules is request_module(), however
+# mount uses get_fs_type(). Both behave slightly differently, but the
+# differences are important enough to test each call separately. For this
+# reason test_kmod starts by providing tests for both calls.
+#
+# The test driver test_kmod assumes a series of defaults which you can
+# override by exporting to your environment prior running this script.
+# For instance this script assumes you do not have xfs loaded upon boot.
+# If this is false, export DEFAULT_KMOD_FS="ext4" prior to running this
+# script if the filesyste module you don't have loaded upon bootup
+# is ext4 instead. Refer to allow_user_defaults() for a list of user
+# override variables possible.
+#
+# You'll want at least 4 GiB of RAM to expect to run these tests
+# without running out of memory on them. For other requirements refer
+# to test_reqs()
+
+set -e
+
+TEST_NAME="kmod"
+TEST_DRIVER="test_${TEST_NAME}"
+TEST_DIR=$(dirname $0)
+
+# This represents
+#
+# TEST_ID:TEST_COUNT:ENABLED
+#
+# TEST_ID: is the test id number
+# TEST_COUNT: number of times we should run the test
+# ENABLED: 1 if enabled, 0 otherwise
+#
+# Once these are enabled please leave them as-is. Write your own test,
+# we have tons of space.
+ALL_TESTS="0001:3:1"
+ALL_TESTS="$ALL_TESTS 0002:3:1"
+ALL_TESTS="$ALL_TESTS 0003:1:1"
+ALL_TESTS="$ALL_TESTS 0004:1:1"
+ALL_TESTS="$ALL_TESTS 0005:10:1"
+ALL_TESTS="$ALL_TESTS 0006:10:1"
+ALL_TESTS="$ALL_TESTS 0007:5:1"
+ALL_TESTS="$ALL_TESTS 0008:150:1"
+ALL_TESTS="$ALL_TESTS 0009:150:1"
+
+test_modprobe()
+{
+       if [ ! -d $DIR ]; then
+               echo "$0: $DIR not present" >&2
+               echo "You must have the following enabled in your kernel:" >&2
+               cat $TEST_DIR/config >&2
+               exit 1
+       fi
+}
+
+function allow_user_defaults()
+{
+	if [ -z $DEFAULT_KMOD_DRIVER ]; then
+		DEFAULT_KMOD_DRIVER="test_module"
+	fi
+
+	if [ -z $DEFAULT_KMOD_FS ]; then
+		DEFAULT_KMOD_FS="xfs"
+	fi
+
+	if [ -z $PROC_DIR ]; then
+		PROC_DIR="/proc/sys/kernel/"
+	fi
+
+	if [ -z $MODPROBE_LIMIT ]; then
+		MODPROBE_LIMIT=50
+	fi
+
+	if [ -z $DIR ]; then
+		DIR="/sys/devices/virtual/misc/${TEST_DRIVER}0/"
+	fi
+
+	if [ -z $DEFAULT_NUM_TESTS ]; then
+		DEFAULT_NUM_TESTS=150
+	fi
+
+	MODPROBE_LIMIT_FILE="${PROC_DIR}/kmod-limit"
+}
+
+test_reqs()
+{
+	if ! which modprobe 2> /dev/null > /dev/null; then
+		echo "$0: You need modprobe installed" >&2
+		exit 1
+	fi
+
+	if ! which kmod 2> /dev/null > /dev/null; then
+		echo "$0: You need kmod installed" >&2
+		exit 1
+	fi
+
+	# kmod 19 has a bad bug where it returns 0 when modprobe
+	# gets called *even* if the module was not loaded due to
+	# some bad heuristics. For details see:
+	#
+	# A work around is possible in-kernel but its rather
+	# complex.
+	KMOD_VERSION=$(kmod --version | awk '{print $3}')
+	if [[ $KMOD_VERSION  -le 19 ]]; then
+		echo "$0: You need at least kmod 20" >&2
+		echo "kmod <= 19 is buggy, for details see:" >&2
+		echo "http://git.kernel.org/cgit/utils/kernel/kmod/kmod.git/commit/libkmod/libkmod-module.c?id=fd44a98ae2eb5eb32161088954ab21e58e19dfc4" >&2
+		exit 1
+	fi
+
+	uid=$(id -u)
+	if [ $uid -ne 0 ]; then
+		echo $msg must be run as root >&2
+		exit 0
+	fi
+}
+
+function load_req_mod()
+{
+	trap "test_modprobe" EXIT
+
+	if [ ! -d $DIR ]; then
+		# Alanis: "Oh isn't it ironic?"
+		modprobe $TEST_DRIVER
+	fi
+}
+
+test_finish()
+{
+	echo "Test completed"
+}
+
+errno_name_to_val()
+{
+	case "$1" in
+	# kmod calls modprobe and upon of a module not found
+	# modprobe returns just 1... However in the kernel we
+	# *sometimes* see 256...
+	MODULE_NOT_FOUND)
+		echo 256;;
+	SUCCESS)
+		echo 0;;
+	-EPERM)
+		echo -1;;
+	-ENOENT)
+		echo -2;;
+	-EINVAL)
+		echo -22;;
+	-ERR_ANY)
+		echo -123456;;
+	*)
+		echo invalid;;
+	esac
+}
+
+errno_val_to_name()
+	case "$1" in
+	256)
+		echo MODULE_NOT_FOUND;;
+	0)
+		echo SUCCESS;;
+	-1)
+		echo -EPERM;;
+	-2)
+		echo -ENOENT;;
+	-22)
+		echo -EINVAL;;
+	-123456)
+		echo -ERR_ANY;;
+	*)
+		echo invalid;;
+	esac
+
+config_set_test_case_driver()
+{
+	if ! echo -n 1 >$DIR/config_test_case; then
+		echo "$0: Unable to set to test case to driver" >&2
+		exit 1
+	fi
+}
+
+config_set_test_case_fs()
+{
+	if ! echo -n 2 >$DIR/config_test_case; then
+		echo "$0: Unable to set to test case to fs" >&2
+		exit 1
+	fi
+}
+
+config_num_threads()
+{
+	if ! echo -n $1 >$DIR/config_num_threads; then
+		echo "$0: Unable to set to number of threads" >&2
+		exit 1
+	fi
+}
+
+config_get_modprobe_limit()
+{
+	if [[ -f ${MODPROBE_LIMIT_FILE} ]] ; then
+		MODPROBE_LIMIT=$(cat $MODPROBE_LIMIT_FILE)
+	fi
+	echo $MODPROBE_LIMIT
+}
+
+config_num_thread_limit_extra()
+{
+	MODPROBE_LIMIT=$(config_get_modprobe_limit)
+	let EXTRA_LIMIT=$MODPROBE_LIMIT+$1
+	config_num_threads $EXTRA_LIMIT
+}
+
+# For special characters use printf directly,
+# refer to kmod_test_0001
+config_set_driver()
+{
+	if ! echo -n $1 >$DIR/config_test_driver; then
+		echo "$0: Unable to set driver" >&2
+		exit 1
+	fi
+}
+
+config_set_fs()
+{
+	if ! echo -n $1 >$DIR/config_test_fs; then
+		echo "$0: Unable to set driver" >&2
+		exit 1
+	fi
+}
+
+config_get_driver()
+{
+	cat $DIR/config_test_driver
+}
+
+config_get_test_result()
+{
+	cat $DIR/test_result
+}
+
+config_reset()
+{
+	if ! echo -n "1" >"$DIR"/reset; then
+		echo "$0: reset shuld have worked" >&2
+		exit 1
+	fi
+}
+
+config_show_config()
+{
+	echo "----------------------------------------------------"
+	cat "$DIR"/config
+	echo "----------------------------------------------------"
+}
+
+config_trigger()
+{
+	if ! echo -n "1" >"$DIR"/trigger_config 2>/dev/null; then
+		echo "$1: FAIL - loading should have worked"
+		config_show_config
+		exit 1
+	fi
+	echo "$1: OK! - loading kmod test"
+}
+
+config_trigger_want_fail()
+{
+	if echo "1" > $DIR/trigger_config 2>/dev/null; then
+		echo "$1: FAIL - test case was expected to fail"
+		config_show_config
+		exit 1
+	fi
+	echo "$1: OK! - kmod test case failed as expected"
+}
+
+config_expect_result()
+{
+	RC=$(config_get_test_result)
+	RC_NAME=$(errno_val_to_name $RC)
+
+	ERRNO_NAME=$2
+	ERRNO=$(errno_name_to_val $ERRNO_NAME)
+
+	if [[ $ERRNO_NAME = "-ERR_ANY" ]]; then
+		if [[ $RC -ge 0 ]]; then
+			echo "$1: FAIL, test expects $ERRNO_NAME - got $RC_NAME ($RC)" >&2
+			config_show_config
+			exit 1
+		fi
+	elif [[ $RC != $ERRNO ]]; then
+		echo "$1: FAIL, test expects $ERRNO_NAME ($ERRNO) - got $RC_NAME ($RC)" >&2
+		config_show_config
+		exit 1
+	fi
+	echo "$1: OK! - Return value: $RC ($RC_NAME), expected $ERRNO_NAME"
+}
+
+kmod_defaults_driver()
+{
+	config_reset
+	modprobe -r $DEFAULT_KMOD_DRIVER
+	config_set_driver $DEFAULT_KMOD_DRIVER
+}
+
+kmod_defaults_fs()
+{
+	config_reset
+	modprobe -r $DEFAULT_KMOD_FS
+	config_set_fs $DEFAULT_KMOD_FS
+	config_set_test_case_fs
+}
+
+kmod_test_0001_driver()
+{
+	NAME='\000'
+
+	kmod_defaults_driver
+	config_num_threads 1
+	printf '\000' >"$DIR"/config_test_driver
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} MODULE_NOT_FOUND
+}
+
+kmod_test_0001_fs()
+{
+	NAME='\000'
+
+	kmod_defaults_fs
+	config_num_threads 1
+	printf '\000' >"$DIR"/config_test_fs
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} -EINVAL
+}
+
+kmod_test_0001()
+{
+	kmod_test_0001_driver
+	kmod_test_0001_fs
+}
+
+kmod_test_0002_driver()
+{
+	NAME="nope-$DEFAULT_KMOD_DRIVER"
+
+	kmod_defaults_driver
+	config_set_driver $NAME
+	config_num_threads 1
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} MODULE_NOT_FOUND
+}
+
+kmod_test_0002_fs()
+{
+	NAME="nope-$DEFAULT_KMOD_FS"
+
+	kmod_defaults_fs
+	config_set_fs $NAME
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} -EINVAL
+}
+
+kmod_test_0002()
+{
+	kmod_test_0002_driver
+	kmod_test_0002_fs
+}
+
+kmod_test_0003()
+{
+	kmod_defaults_fs
+	config_num_threads 1
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+kmod_test_0004()
+{
+	kmod_defaults_fs
+	config_num_threads 2
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+kmod_test_0005()
+{
+	kmod_defaults_driver
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+kmod_test_0006()
+{
+	kmod_defaults_fs
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+kmod_test_0007()
+{
+	kmod_test_0005
+	kmod_test_0006
+}
+
+kmod_test_0008()
+{
+	kmod_defaults_driver
+	MODPROBE_LIMIT=$(config_get_modprobe_limit)
+	let EXTRA=$MODPROBE_LIMIT/6
+	config_num_thread_limit_extra $EXTRA
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+kmod_test_0009()
+{
+	kmod_defaults_fs
+	MODPROBE_LIMIT=$(config_get_modprobe_limit)
+	let EXTRA=$MODPROBE_LIMIT/4
+	config_num_thread_limit_extra $EXTRA
+	config_trigger ${FUNCNAME[0]}
+	config_expect_result ${FUNCNAME[0]} SUCCESS
+}
+
+list_tests()
+{
+	echo "Test ID list:"
+	echo
+	echo "TEST_ID x NUM_TEST"
+	echo "TEST_ID:   Test ID"
+	echo "NUM_TESTS: Number of recommended times to run the test"
+	echo
+	echo "0001 x $(get_test_count 0001) - Simple test - 1 thread  for empty string"
+	echo "0002 x $(get_test_count 0002) - Simple test - 1 thread  for modules/filesystems that do not exist"
+	echo "0003 x $(get_test_count 0003) - Simple test - 1 thread  for get_fs_type() only"
+	echo "0004 x $(get_test_count 0004) - Simple test - 2 threads for get_fs_type() only"
+	echo "0005 x $(get_test_count 0005) - multithreaded tests with default setup - request_module() only"
+	echo "0006 x $(get_test_count 0006) - multithreaded tests with default setup - get_fs_type() only"
+	echo "0007 x $(get_test_count 0007) - multithreaded tests with default setup test request_module() and get_fs_type()"
+	echo "0008 x $(get_test_count 0008) - multithreaded - push kmod_concurrent over max_modprobes for request_module()"
+	echo "0009 x $(get_test_count 0009) - multithreaded - push kmod_concurrent over max_modprobes for get_fs_type()"
+}
+
+usage()
+{
+	NUM_TESTS=$(grep -o ' ' <<<"$ALL_TESTS" | grep -c .)
+	let NUM_TESTS=$NUM_TESTS+1
+	MAX_TEST=$(printf "%04d\n" $NUM_TESTS)
+	echo "Usage: $0 [ -t <4-number-digit> ] | [ -w <4-number-digit> ] |"
+	echo "		 [ -s <4-number-digit> ] | [ -c <4-number-digit> <test- count>"
+	echo "           [ all ] [ -h | --help ] [ -l ]"
+	echo ""
+	echo "Valid tests: 0001-$MAX_TEST"
+	echo ""
+	echo "    all     Runs all tests (default)"
+	echo "    -t      Run test ID the number amount of times is recommended"
+	echo "    -w      Watch test ID run until it runs into an error"
+	echo "    -c      Run test ID once"
+	echo "    -s      Run test ID x test-count number of times"
+	echo "    -l      List all test ID list"
+	echo " -h|--help  Help"
+	echo
+	echo "If an error every occurs execution will immediately terminate."
+	echo "If you are adding a new test try using -w <test-ID> first to"
+	echo "make sure the test passes a series of tests."
+	echo
+	echo Example uses:
+	echo
+	echo "${TEST_NAME}.sh		-- executes all tests"
+	echo "${TEST_NAME}.sh -t 0008	-- Executes test ID 0008 number of times is recomended"
+	echo "${TEST_NAME}.sh -w 0008	-- Watch test ID 0008 run until an error occurs"
+	echo "${TEST_NAME}.sh -s 0008	-- Run test ID 0008 once"
+	echo "${TEST_NAME}.sh -c 0008 3	-- Run test ID 0008 three times"
+	echo
+	list_tests
+	exit 1
+}
+
+function test_num()
+{
+	re='^[0-9]+$'
+	if ! [[ $1 =~ $re ]]; then
+		usage
+	fi
+}
+
+function get_test_count()
+{
+	test_num $1
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	LAST_TWO=${TEST_DATA#*:*}
+	echo ${LAST_TWO%:*}
+}
+
+function get_test_enabled()
+{
+	test_num $1
+	TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$1'}')
+	echo ${TEST_DATA#*:*:}
+}
+
+function run_all_tests()
+{
+	for i in $ALL_TESTS ; do
+		TEST_ID=${i%:*:*}
+		ENABLED=$(get_test_enabled $TEST_ID)
+		TEST_COUNT=$(get_test_count $TEST_ID)
+		if [[ $ENABLED -eq "1" ]]; then
+			test_case $TEST_ID $TEST_COUNT
+		fi
+	done
+}
+
+function watch_log()
+{
+	if [ $# -ne 3 ]; then
+		clear
+	fi
+	date
+	echo "Running test: $2 - run #$1"
+}
+
+function watch_case()
+{
+	i=0
+	while [ 1 ]; do
+
+		if [ $# -eq 1 ]; then
+			test_num $1
+			watch_log $i ${TEST_NAME}_test_$1
+			${TEST_NAME}_test_$1
+		else
+			watch_log $i all
+			run_all_tests
+		fi
+		let i=$i+1
+	done
+}
+
+function test_case()
+{
+	NUM_TESTS=$DEFAULT_NUM_TESTS
+	if [ $# -eq 2 ]; then
+		NUM_TESTS=$2
+	fi
+
+	i=0
+	while [ $i -lt $NUM_TESTS ]; do
+		test_num $1
+		watch_log $i ${TEST_NAME}_test_$1 noclear
+		RUN_TEST=${TEST_NAME}_test_$1
+		$RUN_TEST
+		let i=$i+1
+	done
+}
+
+function parse_args()
+{
+	if [ $# -eq 0 ]; then
+		run_all_tests
+	else
+		if [[ "$1" = "all" ]]; then
+			run_all_tests
+		elif [[ "$1" = "-w" ]]; then
+			shift
+			watch_case $@
+		elif [[ "$1" = "-t" ]]; then
+			shift
+			test_num $1
+			test_case $1 $(get_test_count $1)
+		elif [[ "$1" = "-c" ]]; then
+			shift
+			test_num $1
+			test_num $2
+			test_case $1 $2
+		elif [[ "$1" = "-s" ]]; then
+			shift
+			test_case $1 1
+		elif [[ "$1" = "-l" ]]; then
+			list_tests
+		elif [[ "$1" = "-h" || "$1" = "--help" ]]; then
+			usage
+		else
+			usage
+		fi
+	fi
+}
+
+test_reqs
+allow_user_defaults
+load_req_mod
+
+trap "test_finish" EXIT
+
+parse_args $@
+
+exit 0