Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 620 insertions, 0 deletions

diff --git a/lib/test_lockup.c b/lib/test_lockup.c
new file mode 100644
index 000000000..c3fd87d6c
--- /dev/null
+++ b/lib/test_lockup.c
@@ -0,0 +1,620 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test module to generate lockups
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/clock.h>
+#include <linux/cpu.h>
+#include <linux/nmi.h>
+#include <linux/mm.h>
+#include <linux/uaccess.h>
+#include <linux/file.h>
+
+static unsigned int time_secs;
+module_param(time_secs, uint, 0600);
+MODULE_PARM_DESC(time_secs, "lockup time in seconds, default 0");
+
+static unsigned int time_nsecs;
+module_param(time_nsecs, uint, 0600);
+MODULE_PARM_DESC(time_nsecs, "nanoseconds part of lockup time, default 0");
+
+static unsigned int cooldown_secs;
+module_param(cooldown_secs, uint, 0600);
+MODULE_PARM_DESC(cooldown_secs, "cooldown time between iterations in seconds, default 0");
+
+static unsigned int cooldown_nsecs;
+module_param(cooldown_nsecs, uint, 0600);
+MODULE_PARM_DESC(cooldown_nsecs, "nanoseconds part of cooldown, default 0");
+
+static unsigned int iterations = 1;
+module_param(iterations, uint, 0600);
+MODULE_PARM_DESC(iterations, "lockup iterations, default 1");
+
+static bool all_cpus;
+module_param(all_cpus, bool, 0400);
+MODULE_PARM_DESC(all_cpus, "trigger lockup at all cpus at once");
+
+static int wait_state;
+static char *state = "R";
+module_param(state, charp, 0400);
+MODULE_PARM_DESC(state, "wait in 'R' running (default), 'D' uninterruptible, 'K' killable, 'S' interruptible state");
+
+static bool use_hrtimer;
+module_param(use_hrtimer, bool, 0400);
+MODULE_PARM_DESC(use_hrtimer, "use high-resolution timer for sleeping");
+
+static bool iowait;
+module_param(iowait, bool, 0400);
+MODULE_PARM_DESC(iowait, "account sleep time as iowait");
+
+static bool lock_read;
+module_param(lock_read, bool, 0400);
+MODULE_PARM_DESC(lock_read, "lock read-write locks for read");
+
+static bool lock_single;
+module_param(lock_single, bool, 0400);
+MODULE_PARM_DESC(lock_single, "acquire locks only at one cpu");
+
+static bool reacquire_locks;
+module_param(reacquire_locks, bool, 0400);
+MODULE_PARM_DESC(reacquire_locks, "release and reacquire locks/irq/preempt between iterations");
+
+static bool touch_softlockup;
+module_param(touch_softlockup, bool, 0600);
+MODULE_PARM_DESC(touch_softlockup, "touch soft-lockup watchdog between iterations");
+
+static bool touch_hardlockup;
+module_param(touch_hardlockup, bool, 0600);
+MODULE_PARM_DESC(touch_hardlockup, "touch hard-lockup watchdog between iterations");
+
+static bool call_cond_resched;
+module_param(call_cond_resched, bool, 0600);
+MODULE_PARM_DESC(call_cond_resched, "call cond_resched() between iterations");
+
+static bool measure_lock_wait;
+module_param(measure_lock_wait, bool, 0400);
+MODULE_PARM_DESC(measure_lock_wait, "measure lock wait time");
+
+static unsigned long lock_wait_threshold = ULONG_MAX;
+module_param(lock_wait_threshold, ulong, 0400);
+MODULE_PARM_DESC(lock_wait_threshold, "print lock wait time longer than this in nanoseconds, default off");
+
+static bool test_disable_irq;
+module_param_named(disable_irq, test_disable_irq, bool, 0400);
+MODULE_PARM_DESC(disable_irq, "disable interrupts: generate hard-lockups");
+
+static bool disable_softirq;
+module_param(disable_softirq, bool, 0400);
+MODULE_PARM_DESC(disable_softirq, "disable bottom-half irq handlers");
+
+static bool disable_preempt;
+module_param(disable_preempt, bool, 0400);
+MODULE_PARM_DESC(disable_preempt, "disable preemption: generate soft-lockups");
+
+static bool lock_rcu;
+module_param(lock_rcu, bool, 0400);
+MODULE_PARM_DESC(lock_rcu, "grab rcu_read_lock: generate rcu stalls");
+
+static bool lock_mmap_sem;
+module_param(lock_mmap_sem, bool, 0400);
+MODULE_PARM_DESC(lock_mmap_sem, "lock mm->mmap_lock: block procfs interfaces");
+
+static unsigned long lock_rwsem_ptr;
+module_param_unsafe(lock_rwsem_ptr, ulong, 0400);
+MODULE_PARM_DESC(lock_rwsem_ptr, "lock rw_semaphore at address");
+
+static unsigned long lock_mutex_ptr;
+module_param_unsafe(lock_mutex_ptr, ulong, 0400);
+MODULE_PARM_DESC(lock_mutex_ptr, "lock mutex at address");
+
+static unsigned long lock_spinlock_ptr;
+module_param_unsafe(lock_spinlock_ptr, ulong, 0400);
+MODULE_PARM_DESC(lock_spinlock_ptr, "lock spinlock at address");
+
+static unsigned long lock_rwlock_ptr;
+module_param_unsafe(lock_rwlock_ptr, ulong, 0400);
+MODULE_PARM_DESC(lock_rwlock_ptr, "lock rwlock at address");
+
+static unsigned int alloc_pages_nr;
+module_param_unsafe(alloc_pages_nr, uint, 0600);
+MODULE_PARM_DESC(alloc_pages_nr, "allocate and free pages under locks");
+
+static unsigned int alloc_pages_order;
+module_param(alloc_pages_order, uint, 0400);
+MODULE_PARM_DESC(alloc_pages_order, "page order to allocate");
+
+static gfp_t alloc_pages_gfp = GFP_KERNEL;
+module_param_unsafe(alloc_pages_gfp, uint, 0400);
+MODULE_PARM_DESC(alloc_pages_gfp, "allocate pages with this gfp_mask, default GFP_KERNEL");
+
+static bool alloc_pages_atomic;
+module_param(alloc_pages_atomic, bool, 0400);
+MODULE_PARM_DESC(alloc_pages_atomic, "allocate pages with GFP_ATOMIC");
+
+static bool reallocate_pages;
+module_param(reallocate_pages, bool, 0400);
+MODULE_PARM_DESC(reallocate_pages, "free and allocate pages between iterations");
+
+struct file *test_file;
+static struct inode *test_inode;
+static char test_file_path[256];
+module_param_string(file_path, test_file_path, sizeof(test_file_path), 0400);
+MODULE_PARM_DESC(file_path, "file path to test");
+
+static bool test_lock_inode;
+module_param_named(lock_inode, test_lock_inode, bool, 0400);
+MODULE_PARM_DESC(lock_inode, "lock file -> inode -> i_rwsem");
+
+static bool test_lock_mapping;
+module_param_named(lock_mapping, test_lock_mapping, bool, 0400);
+MODULE_PARM_DESC(lock_mapping, "lock file -> mapping -> i_mmap_rwsem");
+
+static bool test_lock_sb_umount;
+module_param_named(lock_sb_umount, test_lock_sb_umount, bool, 0400);
+MODULE_PARM_DESC(lock_sb_umount, "lock file -> sb -> s_umount");
+
+static atomic_t alloc_pages_failed = ATOMIC_INIT(0);
+
+static atomic64_t max_lock_wait = ATOMIC64_INIT(0);
+
+static struct task_struct *main_task;
+static int master_cpu;
+
+static void test_lock(bool master, bool verbose)
+{
+	u64 wait_start;
+
+	if (measure_lock_wait)
+		wait_start = local_clock();
+
+	if (lock_mutex_ptr && master) {
+		if (verbose)
+			pr_notice("lock mutex %ps\n", (void *)lock_mutex_ptr);
+		mutex_lock((struct mutex *)lock_mutex_ptr);
+	}
+
+	if (lock_rwsem_ptr && master) {
+		if (verbose)
+			pr_notice("lock rw_semaphore %ps\n",
+				  (void *)lock_rwsem_ptr);
+		if (lock_read)
+			down_read((struct rw_semaphore *)lock_rwsem_ptr);
+		else
+			down_write((struct rw_semaphore *)lock_rwsem_ptr);
+	}
+
+	if (lock_mmap_sem && master) {
+		if (verbose)
+			pr_notice("lock mmap_lock pid=%d\n", main_task->pid);
+		if (lock_read)
+			mmap_read_lock(main_task->mm);
+		else
+			mmap_write_lock(main_task->mm);
+	}
+
+	if (test_disable_irq)
+		local_irq_disable();
+
+	if (disable_softirq)
+		local_bh_disable();
+
+	if (disable_preempt)
+		preempt_disable();
+
+	if (lock_rcu)
+		rcu_read_lock();
+
+	if (lock_spinlock_ptr && master) {
+		if (verbose)
+			pr_notice("lock spinlock %ps\n",
+				  (void *)lock_spinlock_ptr);
+		spin_lock((spinlock_t *)lock_spinlock_ptr);
+	}
+
+	if (lock_rwlock_ptr && master) {
+		if (verbose)
+			pr_notice("lock rwlock %ps\n",
+				  (void *)lock_rwlock_ptr);
+		if (lock_read)
+			read_lock((rwlock_t *)lock_rwlock_ptr);
+		else
+			write_lock((rwlock_t *)lock_rwlock_ptr);
+	}
+
+	if (measure_lock_wait) {
+		s64 cur_wait = local_clock() - wait_start;
+		s64 max_wait = atomic64_read(&max_lock_wait);
+
+		do {
+			if (cur_wait < max_wait)
+				break;
+			max_wait = atomic64_cmpxchg(&max_lock_wait,
+						    max_wait, cur_wait);
+		} while (max_wait != cur_wait);
+
+		if (cur_wait > lock_wait_threshold)
+			pr_notice_ratelimited("lock wait %lld ns\n", cur_wait);
+	}
+}
+
+static void test_unlock(bool master, bool verbose)
+{
+	if (lock_rwlock_ptr && master) {
+		if (lock_read)
+			read_unlock((rwlock_t *)lock_rwlock_ptr);
+		else
+			write_unlock((rwlock_t *)lock_rwlock_ptr);
+		if (verbose)
+			pr_notice("unlock rwlock %ps\n",
+				  (void *)lock_rwlock_ptr);
+	}
+
+	if (lock_spinlock_ptr && master) {
+		spin_unlock((spinlock_t *)lock_spinlock_ptr);
+		if (verbose)
+			pr_notice("unlock spinlock %ps\n",
+				  (void *)lock_spinlock_ptr);
+	}
+
+	if (lock_rcu)
+		rcu_read_unlock();
+
+	if (disable_preempt)
+		preempt_enable();
+
+	if (disable_softirq)
+		local_bh_enable();
+
+	if (test_disable_irq)
+		local_irq_enable();
+
+	if (lock_mmap_sem && master) {
+		if (lock_read)
+			mmap_read_unlock(main_task->mm);
+		else
+			mmap_write_unlock(main_task->mm);
+		if (verbose)
+			pr_notice("unlock mmap_lock pid=%d\n", main_task->pid);
+	}
+
+	if (lock_rwsem_ptr && master) {
+		if (lock_read)
+			up_read((struct rw_semaphore *)lock_rwsem_ptr);
+		else
+			up_write((struct rw_semaphore *)lock_rwsem_ptr);
+		if (verbose)
+			pr_notice("unlock rw_semaphore %ps\n",
+				  (void *)lock_rwsem_ptr);
+	}
+
+	if (lock_mutex_ptr && master) {
+		mutex_unlock((struct mutex *)lock_mutex_ptr);
+		if (verbose)
+			pr_notice("unlock mutex %ps\n",
+				  (void *)lock_mutex_ptr);
+	}
+}
+
+static void test_alloc_pages(struct list_head *pages)
+{
+	struct page *page;
+	unsigned int i;
+
+	for (i = 0; i < alloc_pages_nr; i++) {
+		page = alloc_pages(alloc_pages_gfp, alloc_pages_order);
+		if (!page) {
+			atomic_inc(&alloc_pages_failed);
+			break;
+		}
+		list_add(&page->lru, pages);
+	}
+}
+
+static void test_free_pages(struct list_head *pages)
+{
+	struct page *page, *next;
+
+	list_for_each_entry_safe(page, next, pages, lru)
+		__free_pages(page, alloc_pages_order);
+	INIT_LIST_HEAD(pages);
+}
+
+static void test_wait(unsigned int secs, unsigned int nsecs)
+{
+	if (wait_state == TASK_RUNNING) {
+		if (secs)
+			mdelay(secs * MSEC_PER_SEC);
+		if (nsecs)
+			ndelay(nsecs);
+		return;
+	}
+
+	__set_current_state(wait_state);
+	if (use_hrtimer) {
+		ktime_t time;
+
+		time = ns_to_ktime((u64)secs * NSEC_PER_SEC + nsecs);
+		schedule_hrtimeout(&time, HRTIMER_MODE_REL);
+	} else {
+		schedule_timeout(secs * HZ + nsecs_to_jiffies(nsecs));
+	}
+}
+
+static void test_lockup(bool master)
+{
+	u64 lockup_start = local_clock();
+	unsigned int iter = 0;
+	LIST_HEAD(pages);
+
+	pr_notice("Start on CPU%d\n", raw_smp_processor_id());
+
+	test_lock(master, true);
+
+	test_alloc_pages(&pages);
+
+	while (iter++ < iterations && !signal_pending(main_task)) {
+
+		if (iowait)
+			current->in_iowait = 1;
+
+		test_wait(time_secs, time_nsecs);
+
+		if (iowait)
+			current->in_iowait = 0;
+
+		if (reallocate_pages)
+			test_free_pages(&pages);
+
+		if (reacquire_locks)
+			test_unlock(master, false);
+
+		if (touch_softlockup)
+			touch_softlockup_watchdog();
+
+		if (touch_hardlockup)
+			touch_nmi_watchdog();
+
+		if (call_cond_resched)
+			cond_resched();
+
+		test_wait(cooldown_secs, cooldown_nsecs);
+
+		if (reacquire_locks)
+			test_lock(master, false);
+
+		if (reallocate_pages)
+			test_alloc_pages(&pages);
+	}
+
+	pr_notice("Finish on CPU%d in %lld ns\n", raw_smp_processor_id(),
+		  local_clock() - lockup_start);
+
+	test_free_pages(&pages);
+
+	test_unlock(master, true);
+}
+
+static DEFINE_PER_CPU(struct work_struct, test_works);
+
+static void test_work_fn(struct work_struct *work)
+{
+	test_lockup(!lock_single ||
+		    work == per_cpu_ptr(&test_works, master_cpu));
+}
+
+static bool test_kernel_ptr(unsigned long addr, int size)
+{
+	void *ptr = (void *)addr;
+	char buf;
+
+	if (!addr)
+		return false;
+
+	/* should be at least readable kernel address */
+	if (!IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) &&
+	    (access_ok((void __user *)ptr, 1) ||
+	     access_ok((void __user *)ptr + size - 1, 1))) {
+		pr_err("user space ptr invalid in kernel: %#lx\n", addr);
+		return true;
+	}
+
+	if (get_kernel_nofault(buf, ptr) ||
+	    get_kernel_nofault(buf, ptr + size - 1)) {
+		pr_err("invalid kernel ptr: %#lx\n", addr);
+		return true;
+	}
+
+	return false;
+}
+
+static bool __maybe_unused test_magic(unsigned long addr, int offset,
+				      unsigned int expected)
+{
+	void *ptr = (void *)addr + offset;
+	unsigned int magic = 0;
+
+	if (!addr)
+		return false;
+
+	if (get_kernel_nofault(magic, ptr) || magic != expected) {
+		pr_err("invalid magic at %#lx + %#x = %#x, expected %#x\n",
+		       addr, offset, magic, expected);
+		return true;
+	}
+
+	return false;
+}
+
+static int __init test_lockup_init(void)
+{
+	u64 test_start = local_clock();
+
+	main_task = current;
+
+	switch (state[0]) {
+	case 'S':
+		wait_state = TASK_INTERRUPTIBLE;
+		break;
+	case 'D':
+		wait_state = TASK_UNINTERRUPTIBLE;
+		break;
+	case 'K':
+		wait_state = TASK_KILLABLE;
+		break;
+	case 'R':
+		wait_state = TASK_RUNNING;
+		break;
+	default:
+		pr_err("unknown state=%s\n", state);
+		return -EINVAL;
+	}
+
+	if (alloc_pages_atomic)
+		alloc_pages_gfp = GFP_ATOMIC;
+
+	if (test_kernel_ptr(lock_spinlock_ptr, sizeof(spinlock_t)) ||
+	    test_kernel_ptr(lock_rwlock_ptr, sizeof(rwlock_t)) ||
+	    test_kernel_ptr(lock_mutex_ptr, sizeof(struct mutex)) ||
+	    test_kernel_ptr(lock_rwsem_ptr, sizeof(struct rw_semaphore)))
+		return -EINVAL;
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+#ifdef CONFIG_PREEMPT_RT
+	if (test_magic(lock_spinlock_ptr,
+		       offsetof(spinlock_t, lock.wait_lock.magic),
+		       SPINLOCK_MAGIC) ||
+	    test_magic(lock_rwlock_ptr,
+		       offsetof(rwlock_t, rwbase.rtmutex.wait_lock.magic),
+		       SPINLOCK_MAGIC) ||
+	    test_magic(lock_mutex_ptr,
+		       offsetof(struct mutex, rtmutex.wait_lock.magic),
+		       SPINLOCK_MAGIC) ||
+	    test_magic(lock_rwsem_ptr,
+		       offsetof(struct rw_semaphore, rwbase.rtmutex.wait_lock.magic),
+		       SPINLOCK_MAGIC))
+		return -EINVAL;
+#else
+	if (test_magic(lock_spinlock_ptr,
+		       offsetof(spinlock_t, rlock.magic),
+		       SPINLOCK_MAGIC) ||
+	    test_magic(lock_rwlock_ptr,
+		       offsetof(rwlock_t, magic),
+		       RWLOCK_MAGIC) ||
+	    test_magic(lock_mutex_ptr,
+		       offsetof(struct mutex, wait_lock.magic),
+		       SPINLOCK_MAGIC) ||
+	    test_magic(lock_rwsem_ptr,
+		       offsetof(struct rw_semaphore, wait_lock.magic),
+		       SPINLOCK_MAGIC))
+		return -EINVAL;
+#endif
+#endif
+
+	if ((wait_state != TASK_RUNNING ||
+	     (call_cond_resched && !reacquire_locks) ||
+	     (alloc_pages_nr && gfpflags_allow_blocking(alloc_pages_gfp))) &&
+	    (test_disable_irq || disable_softirq || disable_preempt ||
+	     lock_rcu || lock_spinlock_ptr || lock_rwlock_ptr)) {
+		pr_err("refuse to sleep in atomic context\n");
+		return -EINVAL;
+	}
+
+	if (lock_mmap_sem && !main_task->mm) {
+		pr_err("no mm to lock mmap_lock\n");
+		return -EINVAL;
+	}
+
+	if (test_file_path[0]) {
+		test_file = filp_open(test_file_path, O_RDONLY, 0);
+		if (IS_ERR(test_file)) {
+			pr_err("failed to open %s: %ld\n", test_file_path, PTR_ERR(test_file));
+			return PTR_ERR(test_file);
+		}
+		test_inode = file_inode(test_file);
+	} else if (test_lock_inode ||
+		   test_lock_mapping ||
+		   test_lock_sb_umount) {
+		pr_err("no file to lock\n");
+		return -EINVAL;
+	}
+
+	if (test_lock_inode && test_inode)
+		lock_rwsem_ptr = (unsigned long)&test_inode->i_rwsem;
+
+	if (test_lock_mapping && test_file && test_file->f_mapping)
+		lock_rwsem_ptr = (unsigned long)&test_file->f_mapping->i_mmap_rwsem;
+
+	if (test_lock_sb_umount && test_inode)
+		lock_rwsem_ptr = (unsigned long)&test_inode->i_sb->s_umount;
+
+	pr_notice("START pid=%d time=%u +%u ns cooldown=%u +%u ns iterations=%u state=%s %s%s%s%s%s%s%s%s%s%s%s\n",
+		  main_task->pid, time_secs, time_nsecs,
+		  cooldown_secs, cooldown_nsecs, iterations, state,
+		  all_cpus ? "all_cpus " : "",
+		  iowait ? "iowait " : "",
+		  test_disable_irq ? "disable_irq " : "",
+		  disable_softirq ? "disable_softirq " : "",
+		  disable_preempt ? "disable_preempt " : "",
+		  lock_rcu ? "lock_rcu " : "",
+		  lock_read ? "lock_read " : "",
+		  touch_softlockup ? "touch_softlockup " : "",
+		  touch_hardlockup ? "touch_hardlockup " : "",
+		  call_cond_resched ? "call_cond_resched " : "",
+		  reacquire_locks ? "reacquire_locks " : "");
+
+	if (alloc_pages_nr)
+		pr_notice("ALLOCATE PAGES nr=%u order=%u gfp=%pGg %s\n",
+			  alloc_pages_nr, alloc_pages_order, &alloc_pages_gfp,
+			  reallocate_pages ? "reallocate_pages " : "");
+
+	if (all_cpus) {
+		unsigned int cpu;
+
+		cpus_read_lock();
+
+		preempt_disable();
+		master_cpu = smp_processor_id();
+		for_each_online_cpu(cpu) {
+			INIT_WORK(per_cpu_ptr(&test_works, cpu), test_work_fn);
+			queue_work_on(cpu, system_highpri_wq,
+				      per_cpu_ptr(&test_works, cpu));
+		}
+		preempt_enable();
+
+		for_each_online_cpu(cpu)
+			flush_work(per_cpu_ptr(&test_works, cpu));
+
+		cpus_read_unlock();
+	} else {
+		test_lockup(true);
+	}
+
+	if (measure_lock_wait)
+		pr_notice("Maximum lock wait: %lld ns\n",
+			  atomic64_read(&max_lock_wait));
+
+	if (alloc_pages_nr)
+		pr_notice("Page allocation failed %u times\n",
+			  atomic_read(&alloc_pages_failed));
+
+	pr_notice("FINISH in %llu ns\n", local_clock() - test_start);
+
+	if (test_file)
+		fput(test_file);
+
+	if (signal_pending(main_task))
+		return -EINTR;
+
+	return -EAGAIN;
+}
+module_init(test_lockup_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Konstantin Khlebnikov <khlebnikov@yandex-team.ru>");
+MODULE_DESCRIPTION("Test module to generate lockups");