// SPDX-License-Identifier: GPL-2.0+
/*
 * test_xarray.c: Test the XArray API
 * Copyright (c) 2017-2018 Microsoft Corporation
 * Copyright (c) 2019-2020 Oracle
 * Author: Matthew Wilcox <willy@infradead.org>
 */

#include <linux/xarray.h>
#include <linux/module.h>

static unsigned int tests_run;
static unsigned int tests_passed;

static const unsigned int order_limit =
                IS_ENABLED(CONFIG_XARRAY_MULTI) ? BITS_PER_LONG : 1;

#ifndef XA_DEBUG
# ifdef __KERNEL__
void xa_dump(const struct xarray *xa) { }
# endif
#undef XA_BUG_ON
#define XA_BUG_ON(xa, x) do {                                   \
        tests_run++;                                            \
        if (x) {                                                \
                printk("BUG at %s:%d\n", __func__, __LINE__);   \
                xa_dump(xa);                                    \
                dump_stack();                                   \
        } else {                                                \
                tests_passed++;                                 \
        }                                                       \
} while (0)
#endif

static void *xa_mk_index(unsigned long index)
{
        return xa_mk_value(index & LONG_MAX);
}

static void *xa_store_index(struct xarray *xa, unsigned long index, gfp_t gfp)
{
        return xa_store(xa, index, xa_mk_index(index), gfp);
}

static void xa_insert_index(struct xarray *xa, unsigned long index)
{
        XA_BUG_ON(xa, xa_insert(xa, index, xa_mk_index(index),
                                GFP_KERNEL) != 0);
}

static void xa_alloc_index(struct xarray *xa, unsigned long index, gfp_t gfp)
{
        u32 id;

        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(index), xa_limit_32b,
                                gfp) != 0);
        XA_BUG_ON(xa, id != index);
}

static void xa_erase_index(struct xarray *xa, unsigned long index)
{
        XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_index(index));
        XA_BUG_ON(xa, xa_load(xa, index) != NULL);
}

/*
 * If anyone needs this, please move it to xarray.c.  We have no current
 * users outside the test suite because all current multislot users want
 * to use the advanced API.
 */
static void *xa_store_order(struct xarray *xa, unsigned long index,
                unsigned order, void *entry, gfp_t gfp)
{
        XA_STATE_ORDER(xas, xa, index, order);
        void *curr;

        do {
                xas_lock(&xas);
                curr = xas_store(&xas, entry);
                xas_unlock(&xas);
        } while (xas_nomem(&xas, gfp));

        return curr;
}

static noinline void check_xa_err(struct xarray *xa)
{
        XA_BUG_ON(xa, xa_err(xa_store_index(xa, 0, GFP_NOWAIT)) != 0);
        XA_BUG_ON(xa, xa_err(xa_erase(xa, 0)) != 0);
#ifndef __KERNEL__
        /* The kernel does not fail GFP_NOWAIT allocations */
        XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_NOWAIT)) != -ENOMEM);
        XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_NOWAIT)) != -ENOMEM);
#endif
        XA_BUG_ON(xa, xa_err(xa_store_index(xa, 1, GFP_KERNEL)) != 0);
        XA_BUG_ON(xa, xa_err(xa_store(xa, 1, xa_mk_value(0), GFP_KERNEL)) != 0);
        XA_BUG_ON(xa, xa_err(xa_erase(xa, 1)) != 0);
// kills the test-suite :-(
//      XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);
}

static noinline void check_xas_retry(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);
        void *entry;

        xa_store_index(xa, 0, GFP_KERNEL);
        xa_store_index(xa, 1, GFP_KERNEL);

        rcu_read_lock();
        XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_value(0));
        xa_erase_index(xa, 1);
        XA_BUG_ON(xa, !xa_is_retry(xas_reload(&xas)));
        XA_BUG_ON(xa, xas_retry(&xas, NULL));
        XA_BUG_ON(xa, xas_retry(&xas, xa_mk_value(0)));
        xas_reset(&xas);
        XA_BUG_ON(xa, xas.xa_node != XAS_RESTART);
        XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
        XA_BUG_ON(xa, xas.xa_node != NULL);
        rcu_read_unlock();

        XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);

        rcu_read_lock();
        XA_BUG_ON(xa, !xa_is_internal(xas_reload(&xas)));
        xas.xa_node = XAS_RESTART;
        XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
        rcu_read_unlock();

        /* Make sure we can iterate through retry entries */
        xas_lock(&xas);
        xas_set(&xas, 0);
        xas_store(&xas, XA_RETRY_ENTRY);
        xas_set(&xas, 1);
        xas_store(&xas, XA_RETRY_ENTRY);

        xas_set(&xas, 0);
        xas_for_each(&xas, entry, ULONG_MAX) {
                xas_store(&xas, xa_mk_index(xas.xa_index));
        }
        xas_unlock(&xas);

        xa_erase_index(xa, 0);
        xa_erase_index(xa, 1);
}

static noinline void check_xa_load(struct xarray *xa)
{
        unsigned long i, j;

        for (i = 0; i < 1024; i++) {
                for (j = 0; j < 1024; j++) {
                        void *entry = xa_load(xa, j);
                        if (j < i)
                                XA_BUG_ON(xa, xa_to_value(entry) != j);
                        else
                                XA_BUG_ON(xa, entry);
                }
                XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
        }

        for (i = 0; i < 1024; i++) {
                for (j = 0; j < 1024; j++) {
                        void *entry = xa_load(xa, j);
                        if (j >= i)
                                XA_BUG_ON(xa, xa_to_value(entry) != j);
                        else
                                XA_BUG_ON(xa, entry);
                }
                xa_erase_index(xa, i);
        }
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_xa_mark_1(struct xarray *xa, unsigned long index)
{
        unsigned int order;
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 8 : 1;

        /* NULL elements have no marks set */
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
        xa_set_mark(xa, index, XA_MARK_0);
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));

        /* Storing a pointer will not make a mark appear */
        XA_BUG_ON(xa, xa_store_index(xa, index, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
        xa_set_mark(xa, index, XA_MARK_0);
        XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));

        /* Setting one mark will not set another mark */
        XA_BUG_ON(xa, xa_get_mark(xa, index + 1, XA_MARK_0));
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_1));

        /* Storing NULL clears marks, and they can't be set again */
        xa_erase_index(xa, index);
        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));
        xa_set_mark(xa, index, XA_MARK_0);
        XA_BUG_ON(xa, xa_get_mark(xa, index, XA_MARK_0));

        /*
         * Storing a multi-index entry over entries with marks gives the
         * entire entry the union of the marks
         */
        BUG_ON((index % 4) != 0);
        for (order = 2; order < max_order; order++) {
                unsigned long base = round_down(index, 1UL << order);
                unsigned long next = base + (1UL << order);
                unsigned long i;

                XA_BUG_ON(xa, xa_store_index(xa, index + 1, GFP_KERNEL));
                xa_set_mark(xa, index + 1, XA_MARK_0);
                XA_BUG_ON(xa, xa_store_index(xa, index + 2, GFP_KERNEL));
                xa_set_mark(xa, index + 2, XA_MARK_2);
                XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL));
                xa_store_order(xa, index, order, xa_mk_index(index),
                                GFP_KERNEL);
                for (i = base; i < next; i++) {
                        XA_STATE(xas, xa, i);
                        unsigned int seen = 0;
                        void *entry;

                        XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));
                        XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_1));
                        XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_2));

                        /* We should see two elements in the array */
                        rcu_read_lock();
                        xas_for_each(&xas, entry, ULONG_MAX)
                                seen++;
                        rcu_read_unlock();
                        XA_BUG_ON(xa, seen != 2);

                        /* One of which is marked */
                        xas_set(&xas, 0);
                        seen = 0;
                        rcu_read_lock();
                        xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0)
                                seen++;
                        rcu_read_unlock();
                        XA_BUG_ON(xa, seen != 1);
                }
                XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_0));
                XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_1));
                XA_BUG_ON(xa, xa_get_mark(xa, next, XA_MARK_2));
                xa_erase_index(xa, index);
                xa_erase_index(xa, next);
                XA_BUG_ON(xa, !xa_empty(xa));
        }
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_xa_mark_2(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);
        unsigned long index;
        unsigned int count = 0;
        void *entry;

        xa_store_index(xa, 0, GFP_KERNEL);
        xa_set_mark(xa, 0, XA_MARK_0);
        xas_lock(&xas);
        xas_load(&xas);
        xas_init_marks(&xas);
        xas_unlock(&xas);
        XA_BUG_ON(xa, !xa_get_mark(xa, 0, XA_MARK_0) == 0);

        for (index = 3500; index < 4500; index++) {
                xa_store_index(xa, index, GFP_KERNEL);
                xa_set_mark(xa, index, XA_MARK_0);
        }

        xas_reset(&xas);
        rcu_read_lock();
        xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0)
                count++;
        rcu_read_unlock();
        XA_BUG_ON(xa, count != 1000);

        xas_lock(&xas);
        xas_for_each(&xas, entry, ULONG_MAX) {
                xas_init_marks(&xas);
                XA_BUG_ON(xa, !xa_get_mark(xa, xas.xa_index, XA_MARK_0));
                XA_BUG_ON(xa, !xas_get_mark(&xas, XA_MARK_0));
        }
        xas_unlock(&xas);

        xa_destroy(xa);
}

static noinline void check_xa_mark_3(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        XA_STATE(xas, xa, 0x41);
        void *entry;
        int count = 0;

        xa_store_order(xa, 0x40, 2, xa_mk_index(0x40), GFP_KERNEL);
        xa_set_mark(xa, 0x41, XA_MARK_0);

        rcu_read_lock();
        xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_0) {
                count++;
                XA_BUG_ON(xa, entry != xa_mk_index(0x40));
        }
        XA_BUG_ON(xa, count != 1);
        rcu_read_unlock();
        xa_destroy(xa);
#endif
}

static noinline void check_xa_mark(struct xarray *xa)
{
        unsigned long index;

        for (index = 0; index < 16384; index += 4)
                check_xa_mark_1(xa, index);

        check_xa_mark_2(xa);
        check_xa_mark_3(xa);
}

static noinline void check_xa_shrink(struct xarray *xa)
{
        XA_STATE(xas, xa, 1);
        struct xa_node *node;
        unsigned int order;
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 15 : 1;

        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_store_index(xa, 0, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);

        /*
         * Check that erasing the entry at 1 shrinks the tree and properly
         * marks the node as being deleted.
         */
        xas_lock(&xas);
        XA_BUG_ON(xa, xas_load(&xas) != xa_mk_value(1));
        node = xas.xa_node;
        XA_BUG_ON(xa, xa_entry_locked(xa, node, 0) != xa_mk_value(0));
        XA_BUG_ON(xa, xas_store(&xas, NULL) != xa_mk_value(1));
        XA_BUG_ON(xa, xa_load(xa, 1) != NULL);
        XA_BUG_ON(xa, xas.xa_node != XAS_BOUNDS);
        XA_BUG_ON(xa, xa_entry_locked(xa, node, 0) != XA_RETRY_ENTRY);
        XA_BUG_ON(xa, xas_load(&xas) != NULL);
        xas_unlock(&xas);
        XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
        xa_erase_index(xa, 0);
        XA_BUG_ON(xa, !xa_empty(xa));

        for (order = 0; order < max_order; order++) {
                unsigned long max = (1UL << order) - 1;
                xa_store_order(xa, 0, order, xa_mk_value(0), GFP_KERNEL);
                XA_BUG_ON(xa, xa_load(xa, max) != xa_mk_value(0));
                XA_BUG_ON(xa, xa_load(xa, max + 1) != NULL);
                rcu_read_lock();
                node = xa_head(xa);
                rcu_read_unlock();
                XA_BUG_ON(xa, xa_store_index(xa, ULONG_MAX, GFP_KERNEL) !=
                                NULL);
                rcu_read_lock();
                XA_BUG_ON(xa, xa_head(xa) == node);
                rcu_read_unlock();
                XA_BUG_ON(xa, xa_load(xa, max + 1) != NULL);
                xa_erase_index(xa, ULONG_MAX);
                XA_BUG_ON(xa, xa->xa_head != node);
                xa_erase_index(xa, 0);
        }
}

static noinline void check_insert(struct xarray *xa)
{
        unsigned long i;

        for (i = 0; i < 1024; i++) {
                xa_insert_index(xa, i);
                XA_BUG_ON(xa, xa_load(xa, i - 1) != NULL);
                XA_BUG_ON(xa, xa_load(xa, i + 1) != NULL);
                xa_erase_index(xa, i);
        }

        for (i = 10; i < BITS_PER_LONG; i++) {
                xa_insert_index(xa, 1UL << i);
                XA_BUG_ON(xa, xa_load(xa, (1UL << i) - 1) != NULL);
                XA_BUG_ON(xa, xa_load(xa, (1UL << i) + 1) != NULL);
                xa_erase_index(xa, 1UL << i);

                xa_insert_index(xa, (1UL << i) - 1);
                XA_BUG_ON(xa, xa_load(xa, (1UL << i) - 2) != NULL);
                XA_BUG_ON(xa, xa_load(xa, 1UL << i) != NULL);
                xa_erase_index(xa, (1UL << i) - 1);
        }

        xa_insert_index(xa, ~0UL);
        XA_BUG_ON(xa, xa_load(xa, 0UL) != NULL);
        XA_BUG_ON(xa, xa_load(xa, ~1UL) != NULL);
        xa_erase_index(xa, ~0UL);

        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_cmpxchg(struct xarray *xa)
{
        void *FIVE = xa_mk_value(5);
        void *SIX = xa_mk_value(6);
        void *LOTS = xa_mk_value(12345678);

        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_store_index(xa, 12345678, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_insert(xa, 12345678, xa, GFP_KERNEL) != -EBUSY);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, SIX, FIVE, GFP_KERNEL) != LOTS);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, LOTS, FIVE, GFP_KERNEL) != LOTS);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, FIVE, LOTS, GFP_KERNEL) != FIVE);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 5, FIVE, NULL, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 5, NULL, FIVE, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_insert(xa, 5, FIVE, GFP_KERNEL) != -EBUSY);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 5, FIVE, NULL, GFP_KERNEL) != FIVE);
        XA_BUG_ON(xa, xa_insert(xa, 5, FIVE, GFP_KERNEL) == -EBUSY);
        xa_erase_index(xa, 12345678);
        xa_erase_index(xa, 5);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_cmpxchg_order(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        void *FIVE = xa_mk_value(5);
        unsigned int i, order = 3;

        XA_BUG_ON(xa, xa_store_order(xa, 0, order, FIVE, GFP_KERNEL));

        /* Check entry FIVE has the order saved */
        XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != order);

        /* Check all the tied indexes have the same entry and order */
        for (i = 0; i < (1 << order); i++) {
                XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
                XA_BUG_ON(xa, xa_get_order(xa, i) != order);
        }

        /* Ensure that nothing is stored at index '1 << order' */
        XA_BUG_ON(xa, xa_load(xa, 1 << order) != NULL);

        /*
         * Additionally, keep the node information and the order at
         * '1 << order'
         */
        XA_BUG_ON(xa, xa_store_order(xa, 1 << order, order, FIVE, GFP_KERNEL));
        for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
                XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
                XA_BUG_ON(xa, xa_get_order(xa, i) != order);
        }

        /* Conditionally replace FIVE entry at index '0' with NULL */
        XA_BUG_ON(xa, xa_cmpxchg(xa, 0, FIVE, NULL, GFP_KERNEL) != FIVE);

        /* Verify the order is lost at FIVE (and old) entries */
        XA_BUG_ON(xa, xa_get_order(xa, xa_to_value(FIVE)) != 0);

        /* Verify the order and entries are lost in all the tied indexes */
        for (i = 0; i < (1 << order); i++) {
                XA_BUG_ON(xa, xa_load(xa, i) != NULL);
                XA_BUG_ON(xa, xa_get_order(xa, i) != 0);
        }

        /* Verify node and order are kept at '1 << order' */
        for (i = (1 << order); i < (1 << order) + (1 << order) - 1; i++) {
                XA_BUG_ON(xa, xa_load(xa, i) != FIVE);
                XA_BUG_ON(xa, xa_get_order(xa, i) != order);
        }

        xa_store_order(xa, 0, BITS_PER_LONG - 1, NULL, GFP_KERNEL);
        XA_BUG_ON(xa, !xa_empty(xa));
#endif
}

static noinline void check_reserve(struct xarray *xa)
{
        void *entry;
        unsigned long index;
        int count;

        /* An array with a reserved entry is not empty */
        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, xa_empty(xa));
        XA_BUG_ON(xa, xa_load(xa, 12345678));
        xa_release(xa, 12345678);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* Releasing a used entry does nothing */
        XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, xa_store_index(xa, 12345678, GFP_NOWAIT) != NULL);
        xa_release(xa, 12345678);
        xa_erase_index(xa, 12345678);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* cmpxchg sees a reserved entry as ZERO */
        XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, XA_ZERO_ENTRY,
                                xa_mk_value(12345678), GFP_NOWAIT) != NULL);
        xa_release(xa, 12345678);
        xa_erase_index(xa, 12345678);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* xa_insert treats it as busy */
        XA_BUG_ON(xa, xa_reserve(xa, 12345678, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, xa_insert(xa, 12345678, xa_mk_value(12345678), 0) !=
                        -EBUSY);
        XA_BUG_ON(xa, xa_empty(xa));
        XA_BUG_ON(xa, xa_erase(xa, 12345678) != NULL);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* Can iterate through a reserved entry */
        xa_store_index(xa, 5, GFP_KERNEL);
        XA_BUG_ON(xa, xa_reserve(xa, 6, GFP_KERNEL) != 0);
        xa_store_index(xa, 7, GFP_KERNEL);

        count = 0;
        xa_for_each(xa, index, entry) {
                XA_BUG_ON(xa, index != 5 && index != 7);
                count++;
        }
        XA_BUG_ON(xa, count != 2);

        /* If we free a reserved entry, we should be able to allocate it */
        if (xa->xa_flags & XA_FLAGS_ALLOC) {
                u32 id;

                XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(8),
                                        XA_LIMIT(5, 10), GFP_KERNEL) != 0);
                XA_BUG_ON(xa, id != 8);

                xa_release(xa, 6);
                XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_value(6),
                                        XA_LIMIT(5, 10), GFP_KERNEL) != 0);
                XA_BUG_ON(xa, id != 6);
        }

        xa_destroy(xa);
}

static noinline void check_xas_erase(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);
        void *entry;
        unsigned long i, j;

        for (i = 0; i < 200; i++) {
                for (j = i; j < 2 * i + 17; j++) {
                        xas_set(&xas, j);
                        do {
                                xas_lock(&xas);
                                xas_store(&xas, xa_mk_index(j));
                                xas_unlock(&xas);
                        } while (xas_nomem(&xas, GFP_KERNEL));
                }

                xas_set(&xas, ULONG_MAX);
                do {
                        xas_lock(&xas);
                        xas_store(&xas, xa_mk_value(0));
                        xas_unlock(&xas);
                } while (xas_nomem(&xas, GFP_KERNEL));

                xas_lock(&xas);
                xas_store(&xas, NULL);

                xas_set(&xas, 0);
                j = i;
                xas_for_each(&xas, entry, ULONG_MAX) {
                        XA_BUG_ON(xa, entry != xa_mk_index(j));
                        xas_store(&xas, NULL);
                        j++;
                }
                xas_unlock(&xas);
                XA_BUG_ON(xa, !xa_empty(xa));
        }
}

#ifdef CONFIG_XARRAY_MULTI
static noinline void check_multi_store_1(struct xarray *xa, unsigned long index,
                unsigned int order)
{
        XA_STATE(xas, xa, index);
        unsigned long min = index & ~((1UL << order) - 1);
        unsigned long max = min + (1UL << order);

        xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
        XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(index));
        XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(index));
        XA_BUG_ON(xa, xa_load(xa, max) != NULL);
        XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);

        xas_lock(&xas);
        XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(min)) != xa_mk_index(index));
        xas_unlock(&xas);
        XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(min));
        XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(min));
        XA_BUG_ON(xa, xa_load(xa, max) != NULL);
        XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);

        xa_erase_index(xa, min);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_multi_store_2(struct xarray *xa, unsigned long index,
                unsigned int order)
{
        XA_STATE(xas, xa, index);
        xa_store_order(xa, index, order, xa_mk_value(0), GFP_KERNEL);

        xas_lock(&xas);
        XA_BUG_ON(xa, xas_store(&xas, xa_mk_value(1)) != xa_mk_value(0));
        XA_BUG_ON(xa, xas.xa_index != index);
        XA_BUG_ON(xa, xas_store(&xas, NULL) != xa_mk_value(1));
        xas_unlock(&xas);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_multi_store_3(struct xarray *xa, unsigned long index,
                unsigned int order)
{
        XA_STATE(xas, xa, 0);
        void *entry;
        int n = 0;

        xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);

        xas_lock(&xas);
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(index));
                n++;
        }
        XA_BUG_ON(xa, n != 1);
        xas_set(&xas, index + 1);
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(index));
                n++;
        }
        XA_BUG_ON(xa, n != 2);
        xas_unlock(&xas);

        xa_destroy(xa);
}
#endif

static noinline void check_multi_store(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        unsigned long i, j, k;
        unsigned int max_order = (sizeof(long) == 4) ? 30 : 60;

        /* Loading from any position returns the same value */
        xa_store_order(xa, 0, 1, xa_mk_value(0), GFP_KERNEL);
        XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
        XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
        XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
        rcu_read_lock();
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
        rcu_read_unlock();

        /* Storing adjacent to the value does not alter the value */
        xa_store(xa, 3, xa, GFP_KERNEL);
        XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
        XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
        XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
        rcu_read_lock();
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 3);
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
        rcu_read_unlock();

        /* Overwriting multiple indexes works */
        xa_store_order(xa, 0, 2, xa_mk_value(1), GFP_KERNEL);
        XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(1));
        XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(1));
        XA_BUG_ON(xa, xa_load(xa, 2) != xa_mk_value(1));
        XA_BUG_ON(xa, xa_load(xa, 3) != xa_mk_value(1));
        XA_BUG_ON(xa, xa_load(xa, 4) != NULL);
        rcu_read_lock();
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 4);
        XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 4);
        rcu_read_unlock();

        /* We can erase multiple values with a single store */
        xa_store_order(xa, 0, BITS_PER_LONG - 1, NULL, GFP_KERNEL);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* Even when the first slot is empty but the others aren't */
        xa_store_index(xa, 1, GFP_KERNEL);
        xa_store_index(xa, 2, GFP_KERNEL);
        xa_store_order(xa, 0, 2, NULL, GFP_KERNEL);
        XA_BUG_ON(xa, !xa_empty(xa));

        for (i = 0; i < max_order; i++) {
                for (j = 0; j < max_order; j++) {
                        xa_store_order(xa, 0, i, xa_mk_index(i), GFP_KERNEL);
                        xa_store_order(xa, 0, j, xa_mk_index(j), GFP_KERNEL);

                        for (k = 0; k < max_order; k++) {
                                void *entry = xa_load(xa, (1UL << k) - 1);
                                if ((i < k) && (j < k))
                                        XA_BUG_ON(xa, entry != NULL);
                                else
                                        XA_BUG_ON(xa, entry != xa_mk_index(j));
                        }

                        xa_erase(xa, 0);
                        XA_BUG_ON(xa, !xa_empty(xa));
                }
        }

        for (i = 0; i < 20; i++) {
                check_multi_store_1(xa, 200, i);
                check_multi_store_1(xa, 0, i);
                check_multi_store_1(xa, (1UL << i) + 1, i);
        }
        check_multi_store_2(xa, 4095, 9);

        for (i = 1; i < 20; i++) {
                check_multi_store_3(xa, 0, i);
                check_multi_store_3(xa, 1UL << i, i);
        }
#endif
}

#ifdef CONFIG_XARRAY_MULTI
/* mimics page cache __filemap_add_folio() */
static noinline void check_xa_multi_store_adv_add(struct xarray *xa,
                                                  unsigned long index,
                                                  unsigned int order,
                                                  void *p)
{
        XA_STATE(xas, xa, index);
        unsigned int nrpages = 1UL << order;

        /* users are responsible for index alignemnt to the order when adding */
        XA_BUG_ON(xa, index & (nrpages - 1));

        xas_set_order(&xas, index, order);

        do {
                xas_lock_irq(&xas);
                xas_store(&xas, p);
                xas_unlock_irq(&xas);
                /*
                 * In our selftest case the only failure we can expect is for
                 * there not to be enough memory as we're not mimicking the
                 * entire page cache, so verify that's the only error we can run
                 * into here. The xas_nomem() which follows will ensure to fix
                 * that condition for us so to chug on on the loop.
                 */
                XA_BUG_ON(xa, xas_error(&xas) && xas_error(&xas) != -ENOMEM);
        } while (xas_nomem(&xas, GFP_KERNEL));

        XA_BUG_ON(xa, xas_error(&xas));
        XA_BUG_ON(xa, xa_load(xa, index) != p);
}

/* mimics page_cache_delete() */
static noinline void check_xa_multi_store_adv_del_entry(struct xarray *xa,
                                                        unsigned long index,
                                                        unsigned int order)
{
        XA_STATE(xas, xa, index);

        xas_set_order(&xas, index, order);
        xas_store(&xas, NULL);
        xas_init_marks(&xas);
}

static noinline void check_xa_multi_store_adv_delete(struct xarray *xa,
                                                     unsigned long index,
                                                     unsigned int order)
{
        xa_lock_irq(xa);
        check_xa_multi_store_adv_del_entry(xa, index, order);
        xa_unlock_irq(xa);
}

/* mimics page cache filemap_get_entry() */
static noinline void *test_get_entry(struct xarray *xa, unsigned long index)
{
        XA_STATE(xas, xa, index);
        void *p;
        static unsigned int loops = 0;

        rcu_read_lock();
repeat:
        xas_reset(&xas);
        p = xas_load(&xas);
        if (xas_retry(&xas, p))
                goto repeat;
        rcu_read_unlock();

        /*
         * This is not part of the page cache, this selftest is pretty
         * aggressive and does not want to trust the xarray API but rather
         * test it, and for order 20 (4 GiB block size) we can loop over
         * over a million entries which can cause a soft lockup. Page cache
         * APIs won't be stupid, proper page cache APIs loop over the proper
         * order so when using a larger order we skip shared entries.
         */
        if (++loops % XA_CHECK_SCHED == 0)
                schedule();

        return p;
}

static unsigned long some_val = 0xdeadbeef;
static unsigned long some_val_2 = 0xdeaddead;

/* mimics the page cache usage */
static noinline void check_xa_multi_store_adv(struct xarray *xa,
                                              unsigned long pos,
                                              unsigned int order)
{
        unsigned int nrpages = 1UL << order;
        unsigned long index, base, next_index, next_next_index;
        unsigned int i;

        index = pos >> PAGE_SHIFT;
        base = round_down(index, nrpages);
        next_index = round_down(base + nrpages, nrpages);
        next_next_index = round_down(next_index + nrpages, nrpages);

        check_xa_multi_store_adv_add(xa, base, order, &some_val);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, base + i) != &some_val);

        XA_BUG_ON(xa, test_get_entry(xa, next_index) != NULL);

        /* Use order 0 for the next item */
        check_xa_multi_store_adv_add(xa, next_index, 0, &some_val_2);
        XA_BUG_ON(xa, test_get_entry(xa, next_index) != &some_val_2);

        /* Remove the next item */
        check_xa_multi_store_adv_delete(xa, next_index, 0);

        /* Now use order for a new pointer */
        check_xa_multi_store_adv_add(xa, next_index, order, &some_val_2);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, next_index + i) != &some_val_2);

        check_xa_multi_store_adv_delete(xa, next_index, order);
        check_xa_multi_store_adv_delete(xa, base, order);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* starting fresh again */

        /* let's test some holes now */

        /* hole at base and next_next */
        check_xa_multi_store_adv_add(xa, next_index, order, &some_val_2);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, base + i) != NULL);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, next_index + i) != &some_val_2);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, next_next_index + i) != NULL);

        check_xa_multi_store_adv_delete(xa, next_index, order);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* hole at base and next */

        check_xa_multi_store_adv_add(xa, next_next_index, order, &some_val_2);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, base + i) != NULL);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, next_index + i) != NULL);

        for (i = 0; i < nrpages; i++)
                XA_BUG_ON(xa, test_get_entry(xa, next_next_index + i) != &some_val_2);

        check_xa_multi_store_adv_delete(xa, next_next_index, order);
        XA_BUG_ON(xa, !xa_empty(xa));
}
#endif

static noinline void check_multi_store_advanced(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
        unsigned long end = ULONG_MAX/2;
        unsigned long pos, i;

        /*
         * About 117 million tests below.
         */
        for (pos = 7; pos < end; pos = (pos * pos) + 564) {
                for (i = 0; i < max_order; i++) {
                        check_xa_multi_store_adv(xa, pos, i);
                        check_xa_multi_store_adv(xa, pos + 157, i);
                }
        }
#endif
}

static noinline void check_xa_alloc_1(struct xarray *xa, unsigned int base)
{
        int i;
        u32 id;

        XA_BUG_ON(xa, !xa_empty(xa));
        /* An empty array should assign %base to the first alloc */
        xa_alloc_index(xa, base, GFP_KERNEL);

        /* Erasing it should make the array empty again */
        xa_erase_index(xa, base);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* And it should assign %base again */
        xa_alloc_index(xa, base, GFP_KERNEL);

        /* Allocating and then erasing a lot should not lose base */
        for (i = base + 1; i < 2 * XA_CHUNK_SIZE; i++)
                xa_alloc_index(xa, i, GFP_KERNEL);
        for (i = base; i < 2 * XA_CHUNK_SIZE; i++)
                xa_erase_index(xa, i);
        xa_alloc_index(xa, base, GFP_KERNEL);

        /* Destroying the array should do the same as erasing */
        xa_destroy(xa);

        /* And it should assign %base again */
        xa_alloc_index(xa, base, GFP_KERNEL);

        /* The next assigned ID should be base+1 */
        xa_alloc_index(xa, base + 1, GFP_KERNEL);
        xa_erase_index(xa, base + 1);

        /* Storing a value should mark it used */
        xa_store_index(xa, base + 1, GFP_KERNEL);
        xa_alloc_index(xa, base + 2, GFP_KERNEL);

        /* If we then erase base, it should be free */
        xa_erase_index(xa, base);
        xa_alloc_index(xa, base, GFP_KERNEL);

        xa_erase_index(xa, base + 1);
        xa_erase_index(xa, base + 2);

        for (i = 1; i < 5000; i++) {
                xa_alloc_index(xa, base + i, GFP_KERNEL);
        }

        xa_destroy(xa);

        /* Check that we fail properly at the limit of allocation */
        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(UINT_MAX - 1),
                                XA_LIMIT(UINT_MAX - 1, UINT_MAX),
                                GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != 0xfffffffeU);
        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(UINT_MAX),
                                XA_LIMIT(UINT_MAX - 1, UINT_MAX),
                                GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != 0xffffffffU);
        id = 3;
        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(0),
                                XA_LIMIT(UINT_MAX - 1, UINT_MAX),
                                GFP_KERNEL) != -EBUSY);
        XA_BUG_ON(xa, id != 3);
        xa_destroy(xa);

        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(10), XA_LIMIT(10, 5),
                                GFP_KERNEL) != -EBUSY);
        XA_BUG_ON(xa, xa_store_index(xa, 3, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, xa_alloc(xa, &id, xa_mk_index(10), XA_LIMIT(10, 5),
                                GFP_KERNEL) != -EBUSY);
        xa_erase_index(xa, 3);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_xa_alloc_2(struct xarray *xa, unsigned int base)
{
        unsigned int i, id;
        unsigned long index;
        void *entry;

        /* Allocate and free a NULL and check xa_empty() behaves */
        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != base);
        XA_BUG_ON(xa, xa_empty(xa));
        XA_BUG_ON(xa, xa_erase(xa, id) != NULL);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* Ditto, but check destroy instead of erase */
        XA_BUG_ON(xa, !xa_empty(xa));
        XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != base);
        XA_BUG_ON(xa, xa_empty(xa));
        xa_destroy(xa);
        XA_BUG_ON(xa, !xa_empty(xa));

        for (i = base; i < base + 10; i++) {
                XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b,
                                        GFP_KERNEL) != 0);
                XA_BUG_ON(xa, id != i);
        }

        XA_BUG_ON(xa, xa_store(xa, 3, xa_mk_index(3), GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_store(xa, 4, xa_mk_index(4), GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_store(xa, 4, NULL, GFP_KERNEL) != xa_mk_index(4));
        XA_BUG_ON(xa, xa_erase(xa, 5) != NULL);
        XA_BUG_ON(xa, xa_alloc(xa, &id, NULL, xa_limit_32b, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != 5);

        xa_for_each(xa, index, entry) {
                xa_erase_index(xa, index);
        }

        for (i = base; i < base + 9; i++) {
                XA_BUG_ON(xa, xa_erase(xa, i) != NULL);
                XA_BUG_ON(xa, xa_empty(xa));
        }
        XA_BUG_ON(xa, xa_erase(xa, 8) != NULL);
        XA_BUG_ON(xa, xa_empty(xa));
        XA_BUG_ON(xa, xa_erase(xa, base + 9) != NULL);
        XA_BUG_ON(xa, !xa_empty(xa));

        xa_destroy(xa);
}

static noinline void check_xa_alloc_3(struct xarray *xa, unsigned int base)
{
        struct xa_limit limit = XA_LIMIT(1, 0x3fff);
        u32 next = 0;
        unsigned int i, id;
        unsigned long index;
        void *entry;
        int ret;

        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(1), limit,
                                &next, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != 1);

        next = 0x3ffd;
        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(0x3ffd), limit,
                                &next, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != 0x3ffd);
        xa_erase_index(xa, 0x3ffd);
        xa_erase_index(xa, 1);
        XA_BUG_ON(xa, !xa_empty(xa));

        for (i = 0x3ffe; i < 0x4003; i++) {
                if (i < 0x4000)
                        entry = xa_mk_index(i);
                else
                        entry = xa_mk_index(i - 0x3fff);
                XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, entry, limit,
                                        &next, GFP_KERNEL) != 0);
                XA_BUG_ON(xa, xa_mk_index(id) != entry);
        }

        /* Check wrap-around is handled correctly */
        if (base != 0)
                xa_erase_index(xa, base);
        xa_erase_index(xa, base + 1);
        next = UINT_MAX;
        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(UINT_MAX),
                                xa_limit_32b, &next, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != UINT_MAX);
        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base),
                                xa_limit_32b, &next, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != base);
        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base + 1),
                                xa_limit_32b, &next, GFP_KERNEL) != 0);
        XA_BUG_ON(xa, id != base + 1);

        xa_for_each(xa, index, entry)
                xa_erase_index(xa, index);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* check wrap-around return of __xa_alloc_cyclic() */
        next = UINT_MAX;
        XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(UINT_MAX),
                                      xa_limit_32b, &next, GFP_KERNEL) != 0);
        xa_lock(xa);
        ret = __xa_alloc_cyclic(xa, &id, xa_mk_index(base), xa_limit_32b,
                                &next, GFP_KERNEL);
        xa_unlock(xa);
        XA_BUG_ON(xa, ret != 1);
        xa_for_each(xa, index, entry)
                xa_erase_index(xa, index);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static DEFINE_XARRAY_ALLOC(xa0);
static DEFINE_XARRAY_ALLOC1(xa1);

static noinline void check_xa_alloc(void)
{
        check_xa_alloc_1(&xa0, 0);
        check_xa_alloc_1(&xa1, 1);
        check_xa_alloc_2(&xa0, 0);
        check_xa_alloc_2(&xa1, 1);
        check_xa_alloc_3(&xa0, 0);
        check_xa_alloc_3(&xa1, 1);
}

static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
                        unsigned int order, unsigned int present)
{
        XA_STATE_ORDER(xas, xa, start, order);
        void *entry;
        unsigned int count = 0;

retry:
        xas_lock(&xas);
        xas_for_each_conflict(&xas, entry) {
                XA_BUG_ON(xa, !xa_is_value(entry));
                XA_BUG_ON(xa, entry < xa_mk_index(start));
                XA_BUG_ON(xa, entry > xa_mk_index(start + (1UL << order) - 1));
                count++;
        }
        xas_store(&xas, xa_mk_index(start));
        xas_unlock(&xas);
        if (xas_nomem(&xas, GFP_KERNEL)) {
                count = 0;
                goto retry;
        }
        XA_BUG_ON(xa, xas_error(&xas));
        XA_BUG_ON(xa, count != present);
        XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_index(start));
        XA_BUG_ON(xa, xa_load(xa, start + (1UL << order) - 1) !=
                        xa_mk_index(start));
        xa_erase_index(xa, start);
}

static noinline void check_store_iter(struct xarray *xa)
{
        unsigned int i, j;
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;

        for (i = 0; i < max_order; i++) {
                unsigned int min = 1 << i;
                unsigned int max = (2 << i) - 1;
                __check_store_iter(xa, 0, i, 0);
                XA_BUG_ON(xa, !xa_empty(xa));
                __check_store_iter(xa, min, i, 0);
                XA_BUG_ON(xa, !xa_empty(xa));

                xa_store_index(xa, min, GFP_KERNEL);
                __check_store_iter(xa, min, i, 1);
                XA_BUG_ON(xa, !xa_empty(xa));
                xa_store_index(xa, max, GFP_KERNEL);
                __check_store_iter(xa, min, i, 1);
                XA_BUG_ON(xa, !xa_empty(xa));

                for (j = 0; j < min; j++)
                        xa_store_index(xa, j, GFP_KERNEL);
                __check_store_iter(xa, 0, i, min);
                XA_BUG_ON(xa, !xa_empty(xa));
                for (j = 0; j < min; j++)
                        xa_store_index(xa, min + j, GFP_KERNEL);
                __check_store_iter(xa, min, i, min);
                XA_BUG_ON(xa, !xa_empty(xa));
        }
#ifdef CONFIG_XARRAY_MULTI
        xa_store_index(xa, 63, GFP_KERNEL);
        xa_store_index(xa, 65, GFP_KERNEL);
        __check_store_iter(xa, 64, 2, 1);
        xa_erase_index(xa, 63);
#endif
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_multi_find_1(struct xarray *xa, unsigned order)
{
#ifdef CONFIG_XARRAY_MULTI
        unsigned long multi = 3 << order;
        unsigned long next = 4 << order;
        unsigned long index;

        xa_store_order(xa, multi, order, xa_mk_value(multi), GFP_KERNEL);
        XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL) != NULL);
        XA_BUG_ON(xa, xa_store_index(xa, next + 1, GFP_KERNEL) != NULL);

        index = 0;
        XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
                        xa_mk_value(multi));
        XA_BUG_ON(xa, index != multi);
        index = multi + 1;
        XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
                        xa_mk_value(multi));
        XA_BUG_ON(xa, (index < multi) || (index >= next));
        XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=
                        xa_mk_value(next));
        XA_BUG_ON(xa, index != next);
        XA_BUG_ON(xa, xa_find_after(xa, &index, next, XA_PRESENT) != NULL);
        XA_BUG_ON(xa, index != next);

        xa_erase_index(xa, multi);
        xa_erase_index(xa, next);
        xa_erase_index(xa, next + 1);
        XA_BUG_ON(xa, !xa_empty(xa));
#endif
}

static noinline void check_multi_find_2(struct xarray *xa)
{
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 10 : 1;
        unsigned int i, j;
        void *entry;

        for (i = 0; i < max_order; i++) {
                unsigned long index = 1UL << i;
                for (j = 0; j < index; j++) {
                        XA_STATE(xas, xa, j + index);
                        xa_store_index(xa, index - 1, GFP_KERNEL);
                        xa_store_order(xa, index, i, xa_mk_index(index),
                                        GFP_KERNEL);
                        rcu_read_lock();
                        xas_for_each(&xas, entry, ULONG_MAX) {
                                xa_erase_index(xa, index);
                        }
                        rcu_read_unlock();
                        xa_erase_index(xa, index - 1);
                        XA_BUG_ON(xa, !xa_empty(xa));
                }
        }
}

static noinline void check_multi_find_3(struct xarray *xa)
{
        unsigned int order;

        for (order = 5; order < order_limit; order++) {
                unsigned long index = 1UL << (order - 5);

                XA_BUG_ON(xa, !xa_empty(xa));
                xa_store_order(xa, 0, order - 4, xa_mk_index(0), GFP_KERNEL);
                XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT));
                xa_erase_index(xa, 0);
        }
}

static noinline void check_find_1(struct xarray *xa)
{
        unsigned long i, j, k;

        XA_BUG_ON(xa, !xa_empty(xa));

        /*
         * Check xa_find with all pairs between 0 and 99 inclusive,
         * starting at every index between 0 and 99
         */
        for (i = 0; i < 100; i++) {
                XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
                xa_set_mark(xa, i, XA_MARK_0);
                for (j = 0; j < i; j++) {
                        XA_BUG_ON(xa, xa_store_index(xa, j, GFP_KERNEL) !=
                                        NULL);
                        xa_set_mark(xa, j, XA_MARK_0);
                        for (k = 0; k < 100; k++) {
                                unsigned long index = k;
                                void *entry = xa_find(xa, &index, ULONG_MAX,
                                                                XA_PRESENT);
                                if (k <= j)
                                        XA_BUG_ON(xa, index != j);
                                else if (k <= i)
                                        XA_BUG_ON(xa, index != i);
                                else
                                        XA_BUG_ON(xa, entry != NULL);

                                index = k;
                                entry = xa_find(xa, &index, ULONG_MAX,
                                                                XA_MARK_0);
                                if (k <= j)
                                        XA_BUG_ON(xa, index != j);
                                else if (k <= i)
                                        XA_BUG_ON(xa, index != i);
                                else
                                        XA_BUG_ON(xa, entry != NULL);
                        }
                        xa_erase_index(xa, j);
                        XA_BUG_ON(xa, xa_get_mark(xa, j, XA_MARK_0));
                        XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));
                }
                xa_erase_index(xa, i);
                XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_0));
        }
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_find_2(struct xarray *xa)
{
        void *entry;
        unsigned long i, j, index;

        xa_for_each(xa, index, entry) {
                XA_BUG_ON(xa, true);
        }

        for (i = 0; i < 1024; i++) {
                xa_store_index(xa, index, GFP_KERNEL);
                j = 0;
                xa_for_each(xa, index, entry) {
                        XA_BUG_ON(xa, xa_mk_index(index) != entry);
                        XA_BUG_ON(xa, index != j++);
                }
        }

        xa_destroy(xa);
}

static noinline void check_find_3(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);
        unsigned long i, j, k;
        void *entry;

        for (i = 0; i < 100; i++) {
                for (j = 0; j < 100; j++) {
                        rcu_read_lock();
                        for (k = 0; k < 100; k++) {
                                xas_set(&xas, j);
                                xas_for_each_marked(&xas, entry, k, XA_MARK_0)
                                        ;
                                if (j > k)
                                        XA_BUG_ON(xa,
                                                xas.xa_node != XAS_RESTART);
                        }
                        rcu_read_unlock();
                }
                xa_store_index(xa, i, GFP_KERNEL);
                xa_set_mark(xa, i, XA_MARK_0);
        }
        xa_destroy(xa);
}

static noinline void check_find_4(struct xarray *xa)
{
        unsigned long index = 0;
        void *entry;

        xa_store_index(xa, ULONG_MAX, GFP_KERNEL);

        entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT);
        XA_BUG_ON(xa, entry != xa_mk_index(ULONG_MAX));

        entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT);
        XA_BUG_ON(xa, entry);

        xa_erase_index(xa, ULONG_MAX);
}

static noinline void check_find(struct xarray *xa)
{
        unsigned i;

        check_find_1(xa);
        check_find_2(xa);
        check_find_3(xa);
        check_find_4(xa);

        for (i = 2; i < 10; i++)
                check_multi_find_1(xa, i);
        check_multi_find_2(xa);
        check_multi_find_3(xa);
}

/* See find_swap_entry() in mm/shmem.c */
static noinline unsigned long xa_find_entry(struct xarray *xa, void *item)
{
        XA_STATE(xas, xa, 0);
        unsigned int checked = 0;
        void *entry;

        rcu_read_lock();
        xas_for_each(&xas, entry, ULONG_MAX) {
                if (xas_retry(&xas, entry))
                        continue;
                if (entry == item)
                        break;
                checked++;
                if ((checked % 4) != 0)
                        continue;
                xas_pause(&xas);
        }
        rcu_read_unlock();

        return entry ? xas.xa_index : -1;
}

static noinline void check_find_entry(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        unsigned int order;
        unsigned long offset, index;

        for (order = 0; order < 20; order++) {
                for (offset = 0; offset < (1UL << (order + 3));
                     offset += (1UL << order)) {
                        for (index = 0; index < (1UL << (order + 5));
                             index += (1UL << order)) {
                                xa_store_order(xa, index, order,
                                                xa_mk_index(index), GFP_KERNEL);
                                XA_BUG_ON(xa, xa_load(xa, index) !=
                                                xa_mk_index(index));
                                XA_BUG_ON(xa, xa_find_entry(xa,
                                                xa_mk_index(index)) != index);
                        }
                        XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
                        xa_destroy(xa);
                }
        }
#endif

        XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
        xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
        XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
        XA_BUG_ON(xa, xa_find_entry(xa, xa_mk_index(ULONG_MAX)) != -1);
        xa_erase_index(xa, ULONG_MAX);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_pause(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);
        void *entry;
        int order;
        unsigned long index = 1;
        unsigned int count = 0;

        for (order = 0; order < order_limit; order++) {
                XA_BUG_ON(xa, xa_store_order(xa, index, order,
                                        xa_mk_index(index), GFP_KERNEL));
                index += 1UL << order;
        }

        rcu_read_lock();
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
                count++;
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, count != order_limit);

        count = 0;
        xas_set(&xas, 0);
        rcu_read_lock();
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(1UL << count));
                count++;
                xas_pause(&xas);
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, count != order_limit);

        xa_destroy(xa);

        index = 0;
        for (order = order_limit - 1; order >= 0; order--) {
                XA_BUG_ON(xa, xa_store_order(xa, index, order,
                                        xa_mk_index(index), GFP_KERNEL));
                index += 1UL << order;
        }

        index = 0;
        count = 0;
        xas_set(&xas, 0);
        rcu_read_lock();
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(index));
                index += 1UL << (order_limit - count - 1);
                count++;
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, count != order_limit);

        index = 0;
        count = 0;
        /* test unaligned index */
        xas_set(&xas, 1 % (1UL << (order_limit - 1)));
        rcu_read_lock();
        xas_for_each(&xas, entry, ULONG_MAX) {
                XA_BUG_ON(xa, entry != xa_mk_index(index));
                index += 1UL << (order_limit - count - 1);
                count++;
                xas_pause(&xas);
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, count != order_limit);

        xa_destroy(xa);

}

static noinline void check_move_tiny(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);

        XA_BUG_ON(xa, !xa_empty(xa));
        rcu_read_lock();
        XA_BUG_ON(xa, xas_next(&xas) != NULL);
        XA_BUG_ON(xa, xas_next(&xas) != NULL);
        rcu_read_unlock();
        xa_store_index(xa, 0, GFP_KERNEL);
        rcu_read_lock();
        xas_set(&xas, 0);
        XA_BUG_ON(xa, xas_next(&xas) != xa_mk_index(0));
        XA_BUG_ON(xa, xas_next(&xas) != NULL);
        xas_set(&xas, 0);
        XA_BUG_ON(xa, xas_prev(&xas) != xa_mk_index(0));
        XA_BUG_ON(xa, xas_prev(&xas) != NULL);
        rcu_read_unlock();
        xa_erase_index(xa, 0);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_move_max(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);

        xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
        rcu_read_lock();
        XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_index(ULONG_MAX));
        XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != NULL);
        rcu_read_unlock();

        xas_set(&xas, 0);
        rcu_read_lock();
        XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_index(ULONG_MAX));
        xas_pause(&xas);
        XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != NULL);
        rcu_read_unlock();

        xa_erase_index(xa, ULONG_MAX);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_move_small(struct xarray *xa, unsigned long idx)
{
        XA_STATE(xas, xa, 0);
        unsigned long i;

        xa_store_index(xa, 0, GFP_KERNEL);
        xa_store_index(xa, idx, GFP_KERNEL);

        rcu_read_lock();
        for (i = 0; i < idx * 4; i++) {
                void *entry = xas_next(&xas);
                if (i <= idx)
                        XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
                XA_BUG_ON(xa, xas.xa_index != i);
                if (i == 0 || i == idx)
                        XA_BUG_ON(xa, entry != xa_mk_index(i));
                else
                        XA_BUG_ON(xa, entry != NULL);
        }
        xas_next(&xas);
        XA_BUG_ON(xa, xas.xa_index != i);

        do {
                void *entry = xas_prev(&xas);
                i--;
                if (i <= idx)
                        XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
                XA_BUG_ON(xa, xas.xa_index != i);
                if (i == 0 || i == idx)
                        XA_BUG_ON(xa, entry != xa_mk_index(i));
                else
                        XA_BUG_ON(xa, entry != NULL);
        } while (i > 0);

        xas_set(&xas, ULONG_MAX);
        XA_BUG_ON(xa, xas_next(&xas) != NULL);
        XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
        XA_BUG_ON(xa, xas_next(&xas) != xa_mk_value(0));
        XA_BUG_ON(xa, xas.xa_index != 0);
        XA_BUG_ON(xa, xas_prev(&xas) != NULL);
        XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
        rcu_read_unlock();

        xa_erase_index(xa, 0);
        xa_erase_index(xa, idx);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_move(struct xarray *xa)
{
        XA_STATE(xas, xa, (1 << 16) - 1);
        unsigned long i;

        for (i = 0; i < (1 << 16); i++)
                XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);

        rcu_read_lock();
        do {
                void *entry = xas_prev(&xas);
                i--;
                XA_BUG_ON(xa, entry != xa_mk_index(i));
                XA_BUG_ON(xa, i != xas.xa_index);
        } while (i != 0);

        XA_BUG_ON(xa, xas_prev(&xas) != NULL);
        XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);

        do {
                void *entry = xas_next(&xas);
                XA_BUG_ON(xa, entry != xa_mk_index(i));
                XA_BUG_ON(xa, i != xas.xa_index);
                i++;
        } while (i < (1 << 16));
        rcu_read_unlock();

        for (i = (1 << 8); i < (1 << 15); i++)
                xa_erase_index(xa, i);

        i = xas.xa_index;

        rcu_read_lock();
        do {
                void *entry = xas_prev(&xas);
                i--;
                if ((i < (1 << 8)) || (i >= (1 << 15)))
                        XA_BUG_ON(xa, entry != xa_mk_index(i));
                else
                        XA_BUG_ON(xa, entry != NULL);
                XA_BUG_ON(xa, i != xas.xa_index);
        } while (i != 0);

        XA_BUG_ON(xa, xas_prev(&xas) != NULL);
        XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);

        do {
                void *entry = xas_next(&xas);
                if ((i < (1 << 8)) || (i >= (1 << 15)))
                        XA_BUG_ON(xa, entry != xa_mk_index(i));
                else
                        XA_BUG_ON(xa, entry != NULL);
                XA_BUG_ON(xa, i != xas.xa_index);
                i++;
        } while (i < (1 << 16));
        rcu_read_unlock();

        xa_destroy(xa);

        check_move_tiny(xa);
        check_move_max(xa);

        for (i = 0; i < 16; i++)
                check_move_small(xa, 1UL << i);

        for (i = 2; i < 16; i++)
                check_move_small(xa, (1UL << i) - 1);
}

static noinline void xa_store_many_order(struct xarray *xa,
                unsigned long index, unsigned order)
{
        XA_STATE_ORDER(xas, xa, index, order);
        unsigned int i = 0;

        do {
                xas_lock(&xas);
                XA_BUG_ON(xa, xas_find_conflict(&xas));
                xas_create_range(&xas);
                if (xas_error(&xas))
                        goto unlock;
                for (i = 0; i < (1U << order); i++) {
                        XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(index + i)));
                        xas_next(&xas);
                }
unlock:
                xas_unlock(&xas);
        } while (xas_nomem(&xas, GFP_KERNEL));

        XA_BUG_ON(xa, xas_error(&xas));
}

static noinline void check_create_range_1(struct xarray *xa,
                unsigned long index, unsigned order)
{
        unsigned long i;

        xa_store_many_order(xa, index, order);
        for (i = index; i < index + (1UL << order); i++)
                xa_erase_index(xa, i);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_create_range_2(struct xarray *xa, unsigned order)
{
        unsigned long i;
        unsigned long nr = 1UL << order;

        for (i = 0; i < nr * nr; i += nr)
                xa_store_many_order(xa, i, order);
        for (i = 0; i < nr * nr; i++)
                xa_erase_index(xa, i);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_create_range_3(void)
{
        XA_STATE(xas, NULL, 0);
        xas_set_err(&xas, -EEXIST);
        xas_create_range(&xas);
        XA_BUG_ON(NULL, xas_error(&xas) != -EEXIST);
}

static noinline void check_create_range_4(struct xarray *xa,
                unsigned long index, unsigned order)
{
        XA_STATE_ORDER(xas, xa, index, order);
        unsigned long base = xas.xa_index;
        unsigned long i = 0;

        xa_store_index(xa, index, GFP_KERNEL);
        do {
                xas_lock(&xas);
                xas_create_range(&xas);
                if (xas_error(&xas))
                        goto unlock;
                for (i = 0; i < (1UL << order); i++) {
                        void *old = xas_store(&xas, xa_mk_index(base + i));
                        if (xas.xa_index == index)
                                XA_BUG_ON(xa, old != xa_mk_index(base + i));
                        else
                                XA_BUG_ON(xa, old != NULL);
                        xas_next(&xas);
                }
unlock:
                xas_unlock(&xas);
        } while (xas_nomem(&xas, GFP_KERNEL));

        XA_BUG_ON(xa, xas_error(&xas));

        for (i = base; i < base + (1UL << order); i++)
                xa_erase_index(xa, i);
        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_create_range_5(struct xarray *xa,
                unsigned long index, unsigned int order)
{
        XA_STATE_ORDER(xas, xa, index, order);
        unsigned int i;

        xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);

        for (i = 0; i < order + 10; i++) {
                do {
                        xas_lock(&xas);
                        xas_create_range(&xas);
                        xas_unlock(&xas);
                } while (xas_nomem(&xas, GFP_KERNEL));
        }

        xa_destroy(xa);
}

static noinline void check_create_range(struct xarray *xa)
{
        unsigned int order;
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 12 : 1;

        for (order = 0; order < max_order; order++) {
                check_create_range_1(xa, 0, order);
                check_create_range_1(xa, 1U << order, order);
                check_create_range_1(xa, 2U << order, order);
                check_create_range_1(xa, 3U << order, order);
                check_create_range_1(xa, 1U << 24, order);
                if (order < 10)
                        check_create_range_2(xa, order);

                check_create_range_4(xa, 0, order);
                check_create_range_4(xa, 1U << order, order);
                check_create_range_4(xa, 2U << order, order);
                check_create_range_4(xa, 3U << order, order);
                check_create_range_4(xa, 1U << 24, order);

                check_create_range_4(xa, 1, order);
                check_create_range_4(xa, (1U << order) + 1, order);
                check_create_range_4(xa, (2U << order) + 1, order);
                check_create_range_4(xa, (2U << order) - 1, order);
                check_create_range_4(xa, (3U << order) + 1, order);
                check_create_range_4(xa, (3U << order) - 1, order);
                check_create_range_4(xa, (1U << 24) + 1, order);

                check_create_range_5(xa, 0, order);
                check_create_range_5(xa, (1U << order), order);
        }

        check_create_range_3();
}

static noinline void __check_store_range(struct xarray *xa, unsigned long first,
                unsigned long last)
{
#ifdef CONFIG_XARRAY_MULTI
        xa_store_range(xa, first, last, xa_mk_index(first), GFP_KERNEL);

        XA_BUG_ON(xa, xa_load(xa, first) != xa_mk_index(first));
        XA_BUG_ON(xa, xa_load(xa, last) != xa_mk_index(first));
        XA_BUG_ON(xa, xa_load(xa, first - 1) != NULL);
        XA_BUG_ON(xa, xa_load(xa, last + 1) != NULL);

        xa_store_range(xa, first, last, NULL, GFP_KERNEL);
#endif

        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_store_range(struct xarray *xa)
{
        unsigned long i, j;

        for (i = 0; i < 128; i++) {
                for (j = i; j < 128; j++) {
                        __check_store_range(xa, i, j);
                        __check_store_range(xa, 128 + i, 128 + j);
                        __check_store_range(xa, 4095 + i, 4095 + j);
                        __check_store_range(xa, 4096 + i, 4096 + j);
                        __check_store_range(xa, 123456 + i, 123456 + j);
                        __check_store_range(xa, (1 << 24) + i, (1 << 24) + j);
                }
        }
}

#ifdef CONFIG_XARRAY_MULTI
static void check_split_1(struct xarray *xa, unsigned long index,
                                unsigned int order, unsigned int new_order)
{
        XA_STATE_ORDER(xas, xa, index, new_order);
        unsigned int i, found;
        void *entry;

        xa_store_order(xa, index, order, xa, GFP_KERNEL);
        xa_set_mark(xa, index, XA_MARK_1);

        xas_split_alloc(&xas, xa, order, GFP_KERNEL);
        xas_lock(&xas);
        xas_split(&xas, xa, order);
        for (i = 0; i < (1 << order); i += (1 << new_order))
                __xa_store(xa, index + i, xa_mk_index(index + i), 0);
        xas_unlock(&xas);

        for (i = 0; i < (1 << order); i++) {
                unsigned int val = index + (i & ~((1 << new_order) - 1));
                XA_BUG_ON(xa, xa_load(xa, index + i) != xa_mk_index(val));
        }

        xa_set_mark(xa, index, XA_MARK_0);
        XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));

        xas_set_order(&xas, index, 0);
        found = 0;
        rcu_read_lock();
        xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_1) {
                found++;
                XA_BUG_ON(xa, xa_is_internal(entry));
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, found != 1 << (order - new_order));

        xa_destroy(xa);
}

static void check_split_2(struct xarray *xa, unsigned long index,
                                unsigned int order, unsigned int new_order)
{
        XA_STATE_ORDER(xas, xa, index, new_order);
        unsigned int i, found;
        void *entry;

        xa_store_order(xa, index, order, xa, GFP_KERNEL);
        xa_set_mark(xa, index, XA_MARK_1);

        /* allocate a node for xas_try_split() */
        xas_set_err(&xas, -ENOMEM);
        XA_BUG_ON(xa, !xas_nomem(&xas, GFP_KERNEL));

        xas_lock(&xas);
        xas_try_split(&xas, xa, order);
        if (((new_order / XA_CHUNK_SHIFT) < (order / XA_CHUNK_SHIFT)) &&
            new_order < order - 1) {
                XA_BUG_ON(xa, !xas_error(&xas) || xas_error(&xas) != -EINVAL);
                xas_unlock(&xas);
                goto out;
        }
        for (i = 0; i < (1 << order); i += (1 << new_order))
                __xa_store(xa, index + i, xa_mk_index(index + i), 0);
        xas_unlock(&xas);

        for (i = 0; i < (1 << order); i++) {
                unsigned int val = index + (i & ~((1 << new_order) - 1));
                XA_BUG_ON(xa, xa_load(xa, index + i) != xa_mk_index(val));
        }

        xa_set_mark(xa, index, XA_MARK_0);
        XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));

        xas_set_order(&xas, index, 0);
        found = 0;
        rcu_read_lock();
        xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_1) {
                found++;
                XA_BUG_ON(xa, xa_is_internal(entry));
        }
        rcu_read_unlock();
        XA_BUG_ON(xa, found != 1 << (order - new_order));
out:
        xas_destroy(&xas);
        xa_destroy(xa);
}

static noinline void check_split(struct xarray *xa)
{
        unsigned int order, new_order;

        XA_BUG_ON(xa, !xa_empty(xa));

        for (order = 1; order < 2 * XA_CHUNK_SHIFT; order++) {
                for (new_order = 0; new_order < order; new_order++) {
                        check_split_1(xa, 0, order, new_order);
                        check_split_1(xa, 1UL << order, order, new_order);
                        check_split_1(xa, 3UL << order, order, new_order);

                        check_split_2(xa, 0, order, new_order);
                        check_split_2(xa, 1UL << order, order, new_order);
                        check_split_2(xa, 3UL << order, order, new_order);
                }
        }
}
#else
static void check_split(struct xarray *xa) { }
#endif

static void check_align_1(struct xarray *xa, char *name)
{
        int i;
        unsigned int id;
        unsigned long index;
        void *entry;

        for (i = 0; i < 8; i++) {
                XA_BUG_ON(xa, xa_alloc(xa, &id, name + i, xa_limit_32b,
                                        GFP_KERNEL) != 0);
                XA_BUG_ON(xa, id != i);
        }
        xa_for_each(xa, index, entry)
                XA_BUG_ON(xa, xa_is_err(entry));
        xa_destroy(xa);
}

/*
 * We should always be able to store without allocating memory after
 * reserving a slot.
 */
static void check_align_2(struct xarray *xa, char *name)
{
        int i;

        XA_BUG_ON(xa, !xa_empty(xa));

        for (i = 0; i < 8; i++) {
                XA_BUG_ON(xa, xa_store(xa, 0, name + i, GFP_KERNEL) != NULL);
                xa_erase(xa, 0);
        }

        for (i = 0; i < 8; i++) {
                XA_BUG_ON(xa, xa_reserve(xa, 0, GFP_KERNEL) != 0);
                XA_BUG_ON(xa, xa_store(xa, 0, name + i, 0) != NULL);
                xa_erase(xa, 0);
        }

        XA_BUG_ON(xa, !xa_empty(xa));
}

static noinline void check_align(struct xarray *xa)
{
        char name[] = "Motorola 68000";

        check_align_1(xa, name);
        check_align_1(xa, name + 1);
        check_align_1(xa, name + 2);
        check_align_1(xa, name + 3);
        check_align_2(xa, name);
}

static LIST_HEAD(shadow_nodes);

static void test_update_node(struct xa_node *node)
{
        if (node->count && node->count == node->nr_values) {
                if (list_empty(&node->private_list))
                        list_add(&shadow_nodes, &node->private_list);
        } else {
                if (!list_empty(&node->private_list))
                        list_del_init(&node->private_list);
        }
}

static noinline void shadow_remove(struct xarray *xa)
{
        struct xa_node *node;

        xa_lock(xa);
        while ((node = list_first_entry_or_null(&shadow_nodes,
                                        struct xa_node, private_list))) {
                XA_BUG_ON(xa, node->array != xa);
                list_del_init(&node->private_list);
                xa_delete_node(node, test_update_node);
        }
        xa_unlock(xa);
}

static noinline void check_workingset(struct xarray *xa, unsigned long index)
{
        XA_STATE(xas, xa, index);
        xas_set_update(&xas, test_update_node);

        do {
                xas_lock(&xas);
                xas_store(&xas, xa_mk_value(0));
                xas_next(&xas);
                xas_store(&xas, xa_mk_value(1));
                xas_unlock(&xas);
        } while (xas_nomem(&xas, GFP_KERNEL));

        XA_BUG_ON(xa, list_empty(&shadow_nodes));

        xas_lock(&xas);
        xas_next(&xas);
        xas_store(&xas, &xas);
        XA_BUG_ON(xa, !list_empty(&shadow_nodes));

        xas_store(&xas, xa_mk_value(2));
        xas_unlock(&xas);
        XA_BUG_ON(xa, list_empty(&shadow_nodes));

        shadow_remove(xa);
        XA_BUG_ON(xa, !list_empty(&shadow_nodes));
        XA_BUG_ON(xa, !xa_empty(xa));
}

/*
 * Check that the pointer / value / sibling entries are accounted the
 * way we expect them to be.
 */
static noinline void check_account(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
        unsigned int order;

        for (order = 1; order < 12; order++) {
                XA_STATE(xas, xa, 1 << order);

                xa_store_order(xa, 0, order, xa, GFP_KERNEL);
                rcu_read_lock();
                xas_load(&xas);
                XA_BUG_ON(xa, xas.xa_node->count == 0);
                XA_BUG_ON(xa, xas.xa_node->count > (1 << order));
                XA_BUG_ON(xa, xas.xa_node->nr_values != 0);
                rcu_read_unlock();

                xa_store_order(xa, 1 << order, order, xa_mk_index(1UL << order),
                                GFP_KERNEL);
                XA_BUG_ON(xa, xas.xa_node->count != xas.xa_node->nr_values * 2);

                xa_erase(xa, 1 << order);
                XA_BUG_ON(xa, xas.xa_node->nr_values != 0);

                xa_erase(xa, 0);
                XA_BUG_ON(xa, !xa_empty(xa));
        }
#endif
}

static noinline void check_get_order(struct xarray *xa)
{
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
        unsigned int order;
        unsigned long i, j;

        for (i = 0; i < 3; i++)
                XA_BUG_ON(xa, xa_get_order(xa, i) != 0);

        for (order = 0; order < max_order; order++) {
                for (i = 0; i < 10; i++) {
                        xa_store_order(xa, i << order, order,
                                        xa_mk_index(i << order), GFP_KERNEL);
                        for (j = i << order; j < (i + 1) << order; j++)
                                XA_BUG_ON(xa, xa_get_order(xa, j) != order);
                        xa_erase(xa, i << order);
                }
        }
}

static noinline void check_xas_get_order(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);

        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
        unsigned int order;
        unsigned long i, j;

        for (order = 0; order < max_order; order++) {
                for (i = 0; i < 10; i++) {
                        xas_set_order(&xas, i << order, order);
                        do {
                                xas_lock(&xas);
                                xas_store(&xas, xa_mk_value(i));
                                xas_unlock(&xas);
                        } while (xas_nomem(&xas, GFP_KERNEL));

                        for (j = i << order; j < (i + 1) << order; j++) {
                                xas_set_order(&xas, j, 0);
                                rcu_read_lock();
                                xas_load(&xas);
                                XA_BUG_ON(xa, xas_get_order(&xas) != order);
                                rcu_read_unlock();
                        }

                        xas_lock(&xas);
                        xas_set_order(&xas, i << order, order);
                        xas_store(&xas, NULL);
                        xas_unlock(&xas);
                }
        }
}

static noinline void check_xas_conflict_get_order(struct xarray *xa)
{
        XA_STATE(xas, xa, 0);

        void *entry;
        int only_once;
        unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
        unsigned int order;
        unsigned long i, j, k;

        for (order = 0; order < max_order; order++) {
                for (i = 0; i < 10; i++) {
                        xas_set_order(&xas, i << order, order);
                        do {
                                xas_lock(&xas);
                                xas_store(&xas, xa_mk_value(i));
                                xas_unlock(&xas);
                        } while (xas_nomem(&xas, GFP_KERNEL));

                        /*
                         * Ensure xas_get_order works with xas_for_each_conflict.
                         */
                        j = i << order;
                        for (k = 0; k < order; k++) {
                                only_once = 0;
                                xas_set_order(&xas, j + (1 << k), k);
                                xas_lock(&xas);
                                xas_for_each_conflict(&xas, entry) {
                                        XA_BUG_ON(xa, entry != xa_mk_value(i));
                                        XA_BUG_ON(xa, xas_get_order(&xas) != order);
                                        only_once++;
                                }
                                XA_BUG_ON(xa, only_once != 1);
                                xas_unlock(&xas);
                        }

                        if (order < max_order - 1) {
                                only_once = 0;
                                xas_set_order(&xas, (i & ~1UL) << order, order + 1);
                                xas_lock(&xas);
                                xas_for_each_conflict(&xas, entry) {
                                        XA_BUG_ON(xa, entry != xa_mk_value(i));
                                        XA_BUG_ON(xa, xas_get_order(&xas) != order);
                                        only_once++;
                                }
                                XA_BUG_ON(xa, only_once != 1);
                                xas_unlock(&xas);
                        }

                        xas_set_order(&xas, i << order, order);
                        xas_lock(&xas);
                        xas_store(&xas, NULL);
                        xas_unlock(&xas);
                }
        }
}


static noinline void check_destroy(struct xarray *xa)
{
        unsigned long index;

        XA_BUG_ON(xa, !xa_empty(xa));

        /* Destroying an empty array is a no-op */
        xa_destroy(xa);
        XA_BUG_ON(xa, !xa_empty(xa));

        /* Destroying an array with a single entry */
        for (index = 0; index < 1000; index++) {
                xa_store_index(xa, index, GFP_KERNEL);
                XA_BUG_ON(xa, xa_empty(xa));
                xa_destroy(xa);
                XA_BUG_ON(xa, !xa_empty(xa));
        }

        /* Destroying an array with a single entry at ULONG_MAX */
        xa_store(xa, ULONG_MAX, xa, GFP_KERNEL);
        XA_BUG_ON(xa, xa_empty(xa));
        xa_destroy(xa);
        XA_BUG_ON(xa, !xa_empty(xa));

#ifdef CONFIG_XARRAY_MULTI
        /* Destroying an array with a multi-index entry */
        xa_store_order(xa, 1 << 11, 11, xa, GFP_KERNEL);
        XA_BUG_ON(xa, xa_empty(xa));
        xa_destroy(xa);
        XA_BUG_ON(xa, !xa_empty(xa));
#endif
}

static DEFINE_XARRAY(array);

static int xarray_checks(void)
{
        check_xa_err(&array);
        check_xas_retry(&array);
        check_xa_load(&array);
        check_xa_mark(&array);
        check_xa_shrink(&array);
        check_xas_erase(&array);
        check_insert(&array);
        check_cmpxchg(&array);
        check_cmpxchg_order(&array);
        check_reserve(&array);
        check_reserve(&xa0);
        check_multi_store(&array);
        check_multi_store_advanced(&array);
        check_get_order(&array);
        check_xas_get_order(&array);
        check_xas_conflict_get_order(&array);
        check_xa_alloc();
        check_find(&array);
        check_find_entry(&array);
        check_pause(&array);
        check_account(&array);
        check_destroy(&array);
        check_move(&array);
        check_create_range(&array);
        check_store_range(&array);
        check_store_iter(&array);
        check_align(&xa0);
        check_split(&array);

        check_workingset(&array, 0);
        check_workingset(&array, 64);
        check_workingset(&array, 4096);

        printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
        return (tests_run == tests_passed) ? 0 : -EINVAL;
}

static void xarray_exit(void)
{
}

module_init(xarray_checks);
module_exit(xarray_exit);
MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
MODULE_DESCRIPTION("XArray API test module");
MODULE_LICENSE("GPL");