path: root/sys/ofed/drivers/infiniband/debug/memtrack.c

/*
  This software is available to you under a choice of one of two
  licenses.  You may choose to be licensed under the terms of the GNU
  General Public License (GPL) Version 2, available at
  <http://www.fsf.org/copyleft/gpl.html>, or the OpenIB.org BSD
  license, available in the LICENSE.TXT file accompanying this
  software.  These details are also available at
  <http://openib.org/license.html>.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.

  Copyright (c) 2004 Mellanox Technologies Ltd.  All rights reserved.
*/

#define C_MEMTRACK_C

#ifdef kmalloc
        #undef kmalloc
#endif
#ifdef kmemdup
        #undef kmemdup
#endif
#ifdef kfree
        #undef kfree
#endif
#ifdef vmalloc
        #undef vmalloc
#endif
#ifdef vzalloc
        #undef vzalloc
#endif
#ifdef vzalloc_node
        #undef vzalloc_node
#endif
#ifdef vfree
        #undef vfree
#endif
#ifdef kmem_cache_alloc
        #undef kmem_cache_alloc
#endif
#ifdef kmem_cache_free
        #undef kmem_cache_free
#endif
#ifdef ioremap
        #undef ioremap
#endif
#ifdef io_mapping_create_wc
        #undef io_mapping_create_wc
#endif
#ifdef io_mapping_free
        #undef io_mapping_free
#endif
#ifdef ioremap_nocache
        #undef ioremap_nocache
#endif
#ifdef iounmap
        #undef iounmap
#endif
#ifdef alloc_pages
        #undef alloc_pages
#endif
#ifdef free_pages
        #undef free_pages
#endif
#ifdef get_page
        #undef get_page
#endif
#ifdef put_page
        #undef put_page
#endif
#ifdef create_workqueue
        #undef create_workqueue
#endif
#ifdef create_rt_workqueue
        #undef create_rt_workqueue
#endif
#ifdef create_freezeable_workqueue
        #undef create_freezeable_workqueue
#endif
#ifdef create_singlethread_workqueue
        #undef create_singlethread_workqueue
#endif
#ifdef destroy_workqueue
        #undef destroy_workqueue
#endif

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include <linux/proc_fs.h>
#include <linux/random.h>
#include "memtrack.h"

#include <linux/moduleparam.h>


MODULE_AUTHOR("Mellanox Technologies LTD.");
MODULE_DESCRIPTION("Memory allocations tracking");
MODULE_LICENSE("GPL");

#define MEMTRACK_HASH_SZ ((1<<15)-19)   /* prime: http://www.utm.edu/research/primes/lists/2small/0bit.html */
#define MAX_FILENAME_LEN 31

#define memtrack_spin_lock(spl, flags)     spin_lock_irqsave(spl, flags)
#define memtrack_spin_unlock(spl, flags)   spin_unlock_irqrestore(spl, flags)

/* if a bit is set then the corresponding allocation is tracked.
   bit0 corresponds to MEMTRACK_KMALLOC, bit1 corresponds to MEMTRACK_VMALLOC etc. */
static unsigned long track_mask = -1;   /* effectively everything */
module_param(track_mask, ulong, 0444);
MODULE_PARM_DESC(track_mask, "bitmask defining what is tracked");

/* if a bit is set then the corresponding allocation is strictly tracked.
   That is, before inserting the whole range is checked to not overlap any
   of the allocations already in the database */
static unsigned long strict_track_mask = 0;     /* no strict tracking */
module_param(strict_track_mask, ulong, 0444);
MODULE_PARM_DESC(strict_track_mask, "bitmask which allocation requires strict tracking");

/* Sets the frequency of allocations failures injections
   if set to 0 all allocation should succeed */
static unsigned int inject_freq = 0;
module_param(inject_freq, uint, 0644);
MODULE_PARM_DESC(inject_freq, "Error injection frequency, default is 0 (disabled)");

static int random_mem  = 1;
module_param(random_mem, uint, 0644);
MODULE_PARM_DESC(random_mem, "When set, randomize allocated memory, default is 1 (enabled)");

struct memtrack_meminfo_t {
        unsigned long addr;
        unsigned long size;
        unsigned long line_num;
        unsigned long dev;
        unsigned long addr2;
        int direction;
        struct memtrack_meminfo_t *next;
        struct list_head list;  /* used to link all items from a certain type together */
        char filename[MAX_FILENAME_LEN + 1];    /* putting the char array last is better for struct. packing */
        char ext_info[32];
};

static struct kmem_cache *meminfo_cache;

struct tracked_obj_desc_t {
        struct memtrack_meminfo_t *mem_hash[MEMTRACK_HASH_SZ];
        spinlock_t hash_lock;
        unsigned long count; /* size of memory tracked (*malloc) or number of objects tracked */
        struct list_head tracked_objs_head;     /* head of list of all objects */
        int strict_track;       /* if 1 then for each object inserted check if it overlaps any of the objects already in the list */
};

static struct tracked_obj_desc_t *tracked_objs_arr[MEMTRACK_NUM_OF_MEMTYPES];

static const char *rsc_names[MEMTRACK_NUM_OF_MEMTYPES] = {
        "kmalloc",
        "vmalloc",
        "kmem_cache_alloc",
        "io_remap",
        "create_workqueue",
        "alloc_pages",
        "ib_dma_map_single",
        "ib_dma_map_page",
        "ib_dma_map_sg"
};

static const char *rsc_free_names[MEMTRACK_NUM_OF_MEMTYPES] = {
        "kfree",
        "vfree",
        "kmem_cache_free",
        "io_unmap",
        "destory_workqueue",
        "free_pages",
        "ib_dma_unmap_single",
        "ib_dma_unmap_page",
        "ib_dma_unmap_sg"
};

static inline const char *memtype_alloc_str(enum memtrack_memtype_t memtype)
{
        switch (memtype) {
        case MEMTRACK_KMALLOC:
        case MEMTRACK_VMALLOC:
        case MEMTRACK_KMEM_OBJ:
        case MEMTRACK_IOREMAP:
        case MEMTRACK_WORK_QUEUE:
        case MEMTRACK_PAGE_ALLOC:
        case MEMTRACK_DMA_MAP_SINGLE:
        case MEMTRACK_DMA_MAP_PAGE:
        case MEMTRACK_DMA_MAP_SG:
                        return rsc_names[memtype];
                default:
                        return "(Unknown allocation type)";
        }
}

static inline const char *memtype_free_str(enum memtrack_memtype_t memtype)
{
        switch (memtype) {
        case MEMTRACK_KMALLOC:
        case MEMTRACK_VMALLOC:
        case MEMTRACK_KMEM_OBJ:
        case MEMTRACK_IOREMAP:
        case MEMTRACK_WORK_QUEUE:
        case MEMTRACK_PAGE_ALLOC:
        case MEMTRACK_DMA_MAP_SINGLE:
        case MEMTRACK_DMA_MAP_PAGE:
        case MEMTRACK_DMA_MAP_SG:
                        return rsc_free_names[memtype];
                default:
                        return "(Unknown allocation type)";
        }
}

/*
 *  overlap_a_b
 */
static inline int overlap_a_b(unsigned long a_start, unsigned long a_end,
                       unsigned long b_start, unsigned long b_end)
{
        if ((b_start > a_end) || (a_start > b_end))
                return 0;

        return 1;
}

/*
 *  check_overlap
 */
static void check_overlap(enum memtrack_memtype_t memtype,
                          struct memtrack_meminfo_t *mem_info_p,
                          struct tracked_obj_desc_t *obj_desc_p)
{
        struct list_head *pos, *next;
        struct memtrack_meminfo_t *cur;
        unsigned long start_a, end_a, start_b, end_b;

                start_a = mem_info_p->addr;
                end_a = mem_info_p->addr + mem_info_p->size - 1;

        list_for_each_safe(pos, next, &obj_desc_p->tracked_objs_head) {
                cur = list_entry(pos, struct memtrack_meminfo_t, list);

                start_b = cur->addr;
                end_b = cur->addr + cur->size - 1;

                if (overlap_a_b(start_a, end_a, start_b, end_b))
                        printk(KERN_ERR "%s overlaps! new_start=0x%lx, new_end=0x%lx, item_start=0x%lx, item_end=0x%lx\n",
                             memtype_alloc_str(memtype), mem_info_p->addr,
                             mem_info_p->addr + mem_info_p->size - 1, cur->addr,
                             cur->addr + cur->size - 1);
                }
}

/* Invoke on memory allocation */
void memtrack_alloc(enum memtrack_memtype_t memtype, unsigned long dev,
                    unsigned long addr, unsigned long size, unsigned long addr2,
                    int direction, const char *filename,
                    const unsigned long line_num, int alloc_flags)
{
        unsigned long hash_val;
        struct memtrack_meminfo_t *cur_mem_info_p, *new_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;

        if (memtype >= MEMTRACK_NUM_OF_MEMTYPES) {
                printk(KERN_ERR "%s: Invalid memory type (%d)\n", __func__, memtype);
                return;
        }

        if (!tracked_objs_arr[memtype]) {
                /* object is not tracked */
                return;
        }
        obj_desc_p = tracked_objs_arr[memtype];

        hash_val = addr % MEMTRACK_HASH_SZ;

        new_mem_info_p = (struct memtrack_meminfo_t *)kmem_cache_alloc(meminfo_cache, alloc_flags);
        if (new_mem_info_p == NULL) {
                printk(KERN_ERR "%s: Failed allocating kmem_cache item for new mem_info. "
                     "Lost tracking on allocation at %s:%lu...\n", __func__,
                     filename, line_num);
                return;
        }
        /* save allocation properties */
        new_mem_info_p->addr = addr;
        new_mem_info_p->size = size;
        new_mem_info_p->dev = dev;
        new_mem_info_p->addr2 = addr2;
        new_mem_info_p->direction = direction;

        new_mem_info_p->line_num = line_num;
        *new_mem_info_p->ext_info = '\0';
        /* Make sure that we will print out the path tail if the given filename is longer
         * than MAX_FILENAME_LEN. (otherwise, we will not see the name of the actual file
         * in the printout -- only the path head!
         */
        if (strlen(filename) > MAX_FILENAME_LEN)
          strncpy(new_mem_info_p->filename, filename + strlen(filename) - MAX_FILENAME_LEN, MAX_FILENAME_LEN);
        else
          strncpy(new_mem_info_p->filename, filename, MAX_FILENAME_LEN);

        new_mem_info_p->filename[MAX_FILENAME_LEN] = 0; /* NULL terminate anyway */

        memtrack_spin_lock(&obj_desc_p->hash_lock, flags);
        /* make sure given memory location is not already allocated */
        if ((memtype != MEMTRACK_DMA_MAP_SINGLE) && (memtype != MEMTRACK_DMA_MAP_PAGE) &&
            (memtype != MEMTRACK_DMA_MAP_SG)) {

                /* make sure given memory location is not already allocated */
        cur_mem_info_p = obj_desc_p->mem_hash[hash_val];
        while (cur_mem_info_p != NULL) {
                        if ((cur_mem_info_p->addr == addr) && (cur_mem_info_p->dev == dev)) {
                        /* Found given address in the database */
                                printk(KERN_ERR "mtl rsc inconsistency: %s: %s::%lu: %s @ addr=0x%lX which is already known from %s:%lu\n",
                             __func__, filename, line_num,
                             memtype_alloc_str(memtype), addr,
                             cur_mem_info_p->filename,
                             cur_mem_info_p->line_num);
                        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        kmem_cache_free(meminfo_cache, new_mem_info_p);
                        return;
                }
                cur_mem_info_p = cur_mem_info_p->next;
        }
        }
        /* not found - we can put in the hash bucket */
        /* link as first */
        new_mem_info_p->next = obj_desc_p->mem_hash[hash_val];
        obj_desc_p->mem_hash[hash_val] = new_mem_info_p;
        if (obj_desc_p->strict_track)
                check_overlap(memtype, new_mem_info_p, obj_desc_p);
        obj_desc_p->count += size;
        list_add(&new_mem_info_p->list, &obj_desc_p->tracked_objs_head);

        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
        return;
}
EXPORT_SYMBOL(memtrack_alloc);

/* Invoke on memory free */
void memtrack_free(enum memtrack_memtype_t memtype, unsigned long dev,
                   unsigned long addr, unsigned long size, int direction,
                   const char *filename, const unsigned long line_num)
{
        unsigned long hash_val;
        struct memtrack_meminfo_t *cur_mem_info_p, *prev_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;

        if (memtype >= MEMTRACK_NUM_OF_MEMTYPES) {
                printk(KERN_ERR "%s: Invalid memory type (%d)\n", __func__, memtype);
                return;
        }

        if (!tracked_objs_arr[memtype]) {
                /* object is not tracked */
                return;
        }
        obj_desc_p = tracked_objs_arr[memtype];

        hash_val = addr % MEMTRACK_HASH_SZ;

        memtrack_spin_lock(&obj_desc_p->hash_lock, flags);
        /* find  mem_info of given memory location */
        prev_mem_info_p = NULL;
        cur_mem_info_p = obj_desc_p->mem_hash[hash_val];
        while (cur_mem_info_p != NULL) {
                if ((cur_mem_info_p->addr == addr) && (cur_mem_info_p->dev == dev))  {
                        /* Found given address in the database */
                        if ((memtype == MEMTRACK_DMA_MAP_SINGLE) || (memtype == MEMTRACK_DMA_MAP_PAGE) ||
                            (memtype == MEMTRACK_DMA_MAP_SG)) {
                                if (direction != cur_mem_info_p->direction)
                                        printk(KERN_ERR "mtl rsc inconsistency: %s: %s::%lu: %s bad direction for addr 0x%lX: alloc:0x%x, free:0x%x (allocated in %s::%lu)\n",
                                               __func__, filename, line_num, memtype_free_str(memtype), addr, cur_mem_info_p->direction, direction,
                                               cur_mem_info_p->filename, cur_mem_info_p->line_num);

                                if (size != cur_mem_info_p->size)
                                        printk(KERN_ERR "mtl rsc inconsistency: %s: %s::%lu: %s bad size for addr 0x%lX: size:%lu, free:%lu (allocated in %s::%lu)\n",
                                               __func__, filename, line_num, memtype_free_str(memtype), addr, cur_mem_info_p->size, size,
                                               cur_mem_info_p->filename, cur_mem_info_p->line_num);
                        }

                        /* Remove from the bucket/list */
                        if (prev_mem_info_p == NULL)
                                obj_desc_p->mem_hash[hash_val] = cur_mem_info_p->next;  /* removing first */
                        else
                                prev_mem_info_p->next = cur_mem_info_p->next;   /* "crossover" */

                        list_del(&cur_mem_info_p->list);

                        obj_desc_p->count -= cur_mem_info_p->size;
                        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        kmem_cache_free(meminfo_cache, cur_mem_info_p);
                        return;
                }
                prev_mem_info_p = cur_mem_info_p;
                cur_mem_info_p = cur_mem_info_p->next;
        }

        /* not found */
        printk(KERN_ERR "mtl rsc inconsistency: %s: %s::%lu: %s for unknown address=0x%lX, device=0x%lX\n",
               __func__, filename, line_num, memtype_free_str(memtype), addr, dev);
        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
        return;
}
EXPORT_SYMBOL(memtrack_free);

/*
 * This function recognizes allocations which
 * may be released by kernel (e.g. skb) and
 * therefore not trackable by memtrack.
 * The allocations are recognized by the name
 * of their calling function.
 */
int is_non_trackable_alloc_func(const char *func_name)
{
        static const char * const str_str_arr[] = {
                /* functions containing these strings consider non trackable */
                "skb",
        };
        static const char * const str_str_excep_arr[] = {
                /* functions which are exception to the str_str_arr table */
                "ipoib_cm_skb_too_long"
        };
        static const char * const str_cmp_arr[] = {
                /* functions that allocate SKBs */
                "mlx4_en_alloc_frags",
                "mlx4_en_alloc_frag",
                "mlx4_en_init_allocator",
                "mlx4_en_free_frag",
                "mlx4_en_free_rx_desc",
                "mlx4_en_destroy_allocator",
                "mlx4_en_complete_rx_desc",
                /* vnic skb functions */
                "free_single_frag",
                "vnic_alloc_rx_skb",
                "vnic_rx_skb",
                "vnic_alloc_frag",
                "vnic_empty_rx_entry",
                "vnic_init_allocator",
                "vnic_destroy_allocator",
                "sdp_post_recv",
                "sdp_rx_ring_purge",
                "sdp_post_srcavail",
                "sk_stream_alloc_page",
                "update_send_head",
                "sdp_bcopy_get",
                "sdp_destroy_resources",

                /* function that allocate memory for RDMA device context */
                "ib_alloc_device"
        };
        size_t str_str_arr_size = sizeof(str_str_arr)/sizeof(char *);
        size_t str_str_excep_size = sizeof(str_str_excep_arr)/sizeof(char *);
        size_t str_cmp_arr_size = sizeof(str_cmp_arr)/sizeof(char *);

        int i, j;

        for (i = 0; i < str_str_arr_size; ++i)
                if (strstr(func_name, str_str_arr[i])) {
                        for (j = 0; j < str_str_excep_size; ++j)
                                if (!strcmp(func_name, str_str_excep_arr[j]))
                                        return 0;
                        return 1;
                }
        for (i = 0; i < str_cmp_arr_size; ++i)
                if (!strcmp(func_name, str_cmp_arr[i]))
                        return 1;
        return 0;
}
EXPORT_SYMBOL(is_non_trackable_alloc_func);

/*
 * In some cases we need to free a memory
 * we defined as "non trackable" (see
 * is_non_trackable_alloc_func).
 * This function recognizes such releases
 * by the name of their calling function.
 */
int is_non_trackable_free_func(const char *func_name)
{

        static const char * const str_cmp_arr[] = {
                /* function that deallocate memory for RDMA device context */
                "ib_dealloc_device"
        };
        size_t str_cmp_arr_size = sizeof(str_cmp_arr)/sizeof(char *);

        int i;

        for (i = 0; i < str_cmp_arr_size; ++i)
                if (!strcmp(func_name, str_cmp_arr[i]))
                        return 1;
        return 0;
}
EXPORT_SYMBOL(is_non_trackable_free_func);


/* WA - In this function handles confirm
   the the function name is
   '__ib_umem_release' or 'ib_umem_get'
   In this case we won't track the
   memory there because the kernel
   was the one who allocated it.
   Return value:
     1 - if the function name is match, else 0 */
int is_umem_put_page(const char *func_name)
{
        const char func_str[18] = "__ib_umem_release";
        /* In case of error flow put_page is called as part of ib_umem_get */
        const char func_str1[12] = "ib_umem_get";

        return ((strstr(func_name, func_str) != NULL) ||
                (strstr(func_name, func_str1) != NULL)) ? 1 : 0;
}
EXPORT_SYMBOL(is_umem_put_page);

/* Check page order size
   When Freeing a page allocation it checks whether
   we are trying to free the same size
   we asked to allocate                             */
int memtrack_check_size(enum memtrack_memtype_t memtype, unsigned long addr,
                         unsigned long size, const char *filename,
                         const unsigned long line_num)
{
        unsigned long hash_val;
        struct memtrack_meminfo_t *cur_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;
        int ret = 0;

        if (memtype >= MEMTRACK_NUM_OF_MEMTYPES) {
                printk(KERN_ERR "%s: Invalid memory type (%d)\n", __func__, memtype);
                return 1;
        }

        if (!tracked_objs_arr[memtype]) {
                /* object is not tracked */
                return 1;
        }
        obj_desc_p = tracked_objs_arr[memtype];

        hash_val = addr % MEMTRACK_HASH_SZ;

        memtrack_spin_lock(&obj_desc_p->hash_lock, flags);
        /* find mem_info of given memory location */
        cur_mem_info_p = obj_desc_p->mem_hash[hash_val];
        while (cur_mem_info_p != NULL) {
                if (cur_mem_info_p->addr == addr) {
                        /* Found given address in the database - check size */
                        if (cur_mem_info_p->size != size) {
                                printk(KERN_ERR "mtl size inconsistency: %s: %s::%lu: try to %s at address=0x%lX with size %lu while was created with size %lu\n",
                                       __func__, filename, line_num, memtype_free_str(memtype),
                                       addr, size, cur_mem_info_p->size);
                                snprintf(cur_mem_info_p->ext_info, sizeof(cur_mem_info_p->ext_info),
                                                "invalid free size %lu\n", size);
                                ret = 1;
                        }
                        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        return ret;
                }
                cur_mem_info_p = cur_mem_info_p->next;
        }

        /* not found - This function will not give any indication
                       but will only check the correct size\order
                       For inconsistency the 'free' function will check that */
        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
        return 1;
}
EXPORT_SYMBOL(memtrack_check_size);

/* Search for a specific addr whether it exist in the
   current data-base.
   It will print an error msg if we get an unexpected result,
   Return value: 0 - if addr exist, else 1 */
int memtrack_is_new_addr(enum memtrack_memtype_t memtype, unsigned long addr, int expect_exist,
                         const char *filename, const unsigned long line_num)
{
        unsigned long hash_val;
        struct memtrack_meminfo_t *cur_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;

        if (memtype >= MEMTRACK_NUM_OF_MEMTYPES) {
                printk(KERN_ERR "%s: Invalid memory type (%d)\n", __func__, memtype);
                return 1;
        }

        if (!tracked_objs_arr[memtype]) {
                /* object is not tracked */
                return 0;
        }
        obj_desc_p = tracked_objs_arr[memtype];

        hash_val = addr % MEMTRACK_HASH_SZ;

        memtrack_spin_lock(&obj_desc_p->hash_lock, flags);
        /* find mem_info of given memory location */
        cur_mem_info_p = obj_desc_p->mem_hash[hash_val];
        while (cur_mem_info_p != NULL) {
                if (cur_mem_info_p->addr == addr) {
                        /* Found given address in the database - exiting */
                        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        return 0;
                }
                cur_mem_info_p = cur_mem_info_p->next;
        }

        /* not found */
        if (expect_exist)
                printk(KERN_ERR "mtl rsc inconsistency: %s: %s::%lu: %s for unknown address=0x%lX\n",
                       __func__, filename, line_num, memtype_free_str(memtype), addr);

        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
        return 1;
}
EXPORT_SYMBOL(memtrack_is_new_addr);

/* Return current page reference counter */
int memtrack_get_page_ref_count(unsigned long addr)
{
        unsigned long hash_val;
        struct memtrack_meminfo_t *cur_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;
        /* This function is called only for page allocation */
        enum memtrack_memtype_t memtype = MEMTRACK_PAGE_ALLOC;
        int ref_conut = 0;

        if (!tracked_objs_arr[memtype]) {
                /* object is not tracked */
                return ref_conut;
        }
        obj_desc_p = tracked_objs_arr[memtype];

        hash_val = addr % MEMTRACK_HASH_SZ;

        memtrack_spin_lock(&obj_desc_p->hash_lock, flags);
        /* find mem_info of given memory location */
        cur_mem_info_p = obj_desc_p->mem_hash[hash_val];
        while (cur_mem_info_p != NULL) {
                if (cur_mem_info_p->addr == addr) {
                        /* Found given address in the database - check ref-count */
                        struct page *page = (struct page *)(cur_mem_info_p->addr);
                        ref_conut = atomic_read(&page->_count);
                        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        return ref_conut;
                }
                cur_mem_info_p = cur_mem_info_p->next;
        }

        /* not found */
        memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
        return ref_conut;
}
EXPORT_SYMBOL(memtrack_get_page_ref_count);

/* Report current allocations status (for all memory types) */
static void memtrack_report(void)
{
        enum memtrack_memtype_t memtype;
        unsigned long cur_bucket;
        struct memtrack_meminfo_t *cur_mem_info_p;
        int serial = 1;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;
        unsigned long detected_leaks = 0;

        printk(KERN_INFO "%s: Currently known allocations:\n", __func__);
        for (memtype = 0; memtype < MEMTRACK_NUM_OF_MEMTYPES; memtype++) {
                if (tracked_objs_arr[memtype]) {
                        printk(KERN_INFO "%d) %s:\n", serial, memtype_alloc_str(memtype));
                        obj_desc_p = tracked_objs_arr[memtype];
                        /* Scan all buckets to find existing allocations */
                        /* TBD: this may be optimized by holding a linked list of all hash items */
                        for (cur_bucket = 0; cur_bucket < MEMTRACK_HASH_SZ; cur_bucket++) {
                                memtrack_spin_lock(&obj_desc_p->hash_lock, flags);      /* protect per bucket/list */
                                cur_mem_info_p = obj_desc_p->mem_hash[cur_bucket];
                                while (cur_mem_info_p != NULL) {        /* scan bucket */
                                        printk(KERN_INFO "%s::%lu: %s(%lu)==%lX dev=%lX %s\n",
                                               cur_mem_info_p->filename,
                                               cur_mem_info_p->line_num,
                                               memtype_alloc_str(memtype),
                                               cur_mem_info_p->size,
                                               cur_mem_info_p->addr,
                                               cur_mem_info_p->dev,
                                               cur_mem_info_p->ext_info);
                                        cur_mem_info_p = cur_mem_info_p->next;
                                        ++ detected_leaks;
                                }       /* while cur_mem_info_p */
                                memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        }       /* for cur_bucket */
                        serial++;
                }
        }                       /* for memtype */
        printk(KERN_INFO "%s: Summary: %lu leak(s) detected\n", __func__, detected_leaks);
}



static struct proc_dir_entry *memtrack_tree;

static enum memtrack_memtype_t get_rsc_by_name(const char *name)
{
        enum memtrack_memtype_t i;

        for (i = 0; i < MEMTRACK_NUM_OF_MEMTYPES; ++i) {
                if (strcmp(name, rsc_names[i]) == 0)
                        return i;
                }

        return i;
}


static ssize_t memtrack_read(struct file *filp,
                                                 char __user *buf,
                                                         size_t size,
                                                         loff_t *offset)
{
        unsigned long cur, flags;
        loff_t pos = *offset;
        static char kbuf[20];
        static int file_len;
        int _read, to_ret, left;
        const char *fname;
        enum memtrack_memtype_t memtype;

        if (pos < 0)
                return -EINVAL;

        fname = filp->f_dentry->d_name.name;

        memtype = get_rsc_by_name(fname);
        if (memtype >= MEMTRACK_NUM_OF_MEMTYPES) {
                printk(KERN_ERR "invalid file name\n");
                return -EINVAL;
        }

        if (pos == 0) {
                memtrack_spin_lock(&tracked_objs_arr[memtype]->hash_lock, flags);
                cur = tracked_objs_arr[memtype]->count;
                memtrack_spin_unlock(&tracked_objs_arr[memtype]->hash_lock, flags);
                _read = sprintf(kbuf, "%lu\n", cur);
                if (_read < 0)
                        return _read;
                else
                        file_len = _read;
                }

        left = file_len - pos;
        to_ret = (left < size) ? left : size;
        if (copy_to_user(buf, kbuf+pos, to_ret))
                return -EFAULT;
        else {
                *offset = pos + to_ret;
                return to_ret;
        }
}

static const struct file_operations memtrack_proc_fops = {
        .read = memtrack_read,
};

static const char *memtrack_proc_entry_name = "mt_memtrack";

static int create_procfs_tree(void)
{
        struct proc_dir_entry *dir_ent;
        struct proc_dir_entry *proc_ent;
        int i, j;
        unsigned long bit_mask;

        dir_ent = proc_mkdir(memtrack_proc_entry_name, NULL);
        if (!dir_ent)
                return -1;

        memtrack_tree = dir_ent;

        for (i = 0, bit_mask = 1; i < MEMTRACK_NUM_OF_MEMTYPES; ++i, bit_mask <<= 1) {
                if (bit_mask & track_mask) {
                        proc_ent = create_proc_entry(rsc_names[i], S_IRUGO, memtrack_tree);
                        if (!proc_ent)
                                goto undo_create_root;

                        proc_ent->proc_fops = &memtrack_proc_fops;
                }
        }

        goto exit_ok;

undo_create_root:
        for (j = 0, bit_mask = 1; j < i; ++j, bit_mask <<= 1) {
                if (bit_mask & track_mask)
                        remove_proc_entry(rsc_names[j], memtrack_tree);
                }
        remove_proc_entry(memtrack_proc_entry_name, NULL);
        return -1;

exit_ok:
        return 0;
}


static void destroy_procfs_tree(void)
{
        int i;
        unsigned long bit_mask;

        for (i = 0, bit_mask = 1; i < MEMTRACK_NUM_OF_MEMTYPES; ++i, bit_mask <<= 1) {
                if (bit_mask & track_mask)
                        remove_proc_entry(rsc_names[i], memtrack_tree);

        }
        remove_proc_entry(memtrack_proc_entry_name, NULL);
}

int memtrack_inject_error(void)
{
        int val = 0;

        if (inject_freq) {
                if (!(random32() % inject_freq))
                        val = 1;
        }

        return val;
}
EXPORT_SYMBOL(memtrack_inject_error);

int memtrack_randomize_mem(void)
{
        return random_mem;
}
EXPORT_SYMBOL(memtrack_randomize_mem);

/* module entry points */

int init_module(void)
{
        enum memtrack_memtype_t i;
        int j;
        unsigned long bit_mask;


        /* create a cache for the memtrack_meminfo_t strcutures */
        meminfo_cache = kmem_cache_create("memtrack_meminfo_t",
                                          sizeof(struct memtrack_meminfo_t), 0,
                                          SLAB_HWCACHE_ALIGN, NULL);
        if (!meminfo_cache) {
                printk(KERN_ERR "memtrack::%s: failed to allocate meminfo cache\n", __func__);
                return -1;
        }

        /* initialize array of descriptors */
        memset(tracked_objs_arr, 0, sizeof(tracked_objs_arr));

        /* create a tracking object descriptor for all required objects */
        for (i = 0, bit_mask = 1; i < MEMTRACK_NUM_OF_MEMTYPES; ++i, bit_mask <<= 1) {
                if (bit_mask & track_mask) {
                        tracked_objs_arr[i] = vmalloc(sizeof(struct tracked_obj_desc_t));
                        if (!tracked_objs_arr[i]) {
                                printk(KERN_ERR "memtrack: failed to allocate tracking object\n");
                                goto undo_cache_create;
                        }

                        memset(tracked_objs_arr[i], 0, sizeof(struct tracked_obj_desc_t));
                        spin_lock_init(&tracked_objs_arr[i]->hash_lock);
                        INIT_LIST_HEAD(&tracked_objs_arr[i]->tracked_objs_head);
                        if (bit_mask & strict_track_mask)
                                tracked_objs_arr[i]->strict_track = 1;
                        else
                                tracked_objs_arr[i]->strict_track = 0;
                        }
                }


        if (create_procfs_tree()) {
                printk(KERN_ERR "%s: create_procfs_tree() failed\n", __FILE__);
                  goto undo_cache_create;
        }

        printk(KERN_INFO "memtrack::%s done.\n", __func__);

        return 0;

undo_cache_create:
        for (j = 0; j < i; ++j) {
                if (tracked_objs_arr[j])
                        vfree(tracked_objs_arr[j]);
                }

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
        if (kmem_cache_destroy(meminfo_cache) != 0)
                printk(KERN_ERR "Failed on kmem_cache_destroy!\n");
#else
        kmem_cache_destroy(meminfo_cache);
#endif
        return -1;
}


void cleanup_module(void)
{
        enum memtrack_memtype_t memtype;
        unsigned long cur_bucket;
        struct memtrack_meminfo_t *cur_mem_info_p, *next_mem_info_p;
        struct tracked_obj_desc_t *obj_desc_p;
        unsigned long flags;


        memtrack_report();


        destroy_procfs_tree();

        /* clean up any hash table left-overs */
        for (memtype = 0; memtype < MEMTRACK_NUM_OF_MEMTYPES; memtype++) {
                /* Scan all buckets to find existing allocations */
                /* TBD: this may be optimized by holding a linked list of all hash items */
                if (tracked_objs_arr[memtype]) {
                        obj_desc_p = tracked_objs_arr[memtype];
                        for (cur_bucket = 0; cur_bucket < MEMTRACK_HASH_SZ; cur_bucket++) {
                                memtrack_spin_lock(&obj_desc_p->hash_lock, flags);      /* protect per bucket/list */
                                cur_mem_info_p = obj_desc_p->mem_hash[cur_bucket];
                                while (cur_mem_info_p != NULL) {        /* scan bucket */
                                        next_mem_info_p = cur_mem_info_p->next; /* save "next" pointer before the "free" */
                                        kmem_cache_free(meminfo_cache, cur_mem_info_p);
                                        cur_mem_info_p = next_mem_info_p;
                                }       /* while cur_mem_info_p */
                                memtrack_spin_unlock(&obj_desc_p->hash_lock, flags);
                        }       /* for cur_bucket */
                        vfree(obj_desc_p);
                }
        }                       /* for memtype */

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
        if (kmem_cache_destroy(meminfo_cache) != 0)
                printk(KERN_ERR "memtrack::cleanup_module: Failed on kmem_cache_destroy!\n");
#else
        kmem_cache_destroy(meminfo_cache);
#endif
        printk(KERN_INFO "memtrack::cleanup_module done.\n");
}