diff options
| -rw-r--r-- | lib/Kconfig.debug | 12 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/test_lockup.c | 554 |
3 files changed, 567 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 7f9a89847b65..ddcf000022ae 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -976,6 +976,18 @@ config WQ_WATCHDOG state. This can be configured through kernel parameter "workqueue.watchdog_thresh" and its sysfs counterpart. +config TEST_LOCKUP + tristate "Test module to generate lockups" + help + This builds the "test_lockup" module that helps to make sure + that watchdogs and lockup detectors are working properly. + + Depending on module parameters it could emulate soft or hard + lockup, "hung task", or locking arbitrary lock for a long time. + Also it could generate series of lockups with cooling-down periods. + + If unsure, say N. + endmenu # "Debug lockups and hangs" menu "Scheduler Debugging" diff --git a/lib/Makefile b/lib/Makefile index 09a8acb0cf92..0fd125c4ad07 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -90,6 +90,7 @@ obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o +obj-$(CONFIG_TEST_LOCKUP) += test_lockup.o obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/ diff --git a/lib/test_lockup.c b/lib/test_lockup.c new file mode 100644 index 000000000000..9e8b8a0be9af --- /dev/null +++ b/lib/test_lockup.c @@ -0,0 +1,554 @@ +// 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> + +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_sem: 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"); + +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 uninitialized_var(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_sem pid=%d\n", main_task->pid); + if (lock_read) + down_read(&main_task->mm->mmap_sem); + else + down_write(&main_task->mm->mmap_sem); + } + + 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) + up_read(&main_task->mm->mmap_sem); + else + up_write(&main_task->mm->mmap_sem); + if (verbose) + pr_notice("unlock mmap_sem 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); +} + +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 (access_ok(ptr, 1) || + access_ok(ptr + size - 1, 1) || + probe_kernel_address(ptr, buf) || + probe_kernel_address(ptr + size - 1, buf)) { + 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 (probe_kernel_address(ptr, magic) || 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 + 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.rlock.magic), + SPINLOCK_MAGIC) || + test_magic(lock_rwsem_ptr, + offsetof(struct rw_semaphore, wait_lock.magic), + SPINLOCK_MAGIC)) + return -EINVAL; +#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_sem\n"); + return -EINVAL; + } + + pr_notice("START pid=%d time=%u +%u ns cooldown=%u +%u ns iteraions=%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 (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"); |