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-rw-r--r--mm/mempool.c92
1 files changed, 90 insertions, 2 deletions
diff --git a/mm/mempool.c b/mm/mempool.c
index b60fb85..2884d5b 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -6,10 +6,12 @@
* extreme VM load.
*
* started by Ingo Molnar, Copyright (C) 2001
+ * debugging by David Rientjes, Copyright (C) 2015
*/
#include <linux/mm.h>
#include <linux/slab.h>
+#include <linux/highmem.h>
#include <linux/kmemleak.h>
#include <linux/export.h>
#include <linux/mempool.h>
@@ -17,16 +19,102 @@
#include <linux/writeback.h>
#include "slab.h"
+#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
+static void poison_error(mempool_t *pool, void *element, size_t size,
+ size_t byte)
+{
+ const int nr = pool->curr_nr;
+ const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
+ const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
+ int i;
+
+ pr_err("BUG: mempool element poison mismatch\n");
+ pr_err("Mempool %p size %zu\n", pool, size);
+ pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
+ for (i = start; i < end; i++)
+ pr_cont("%x ", *(u8 *)(element + i));
+ pr_cont("%s\n", end < size ? "..." : "");
+ dump_stack();
+}
+
+static void __check_element(mempool_t *pool, void *element, size_t size)
+{
+ u8 *obj = element;
+ size_t i;
+
+ for (i = 0; i < size; i++) {
+ u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
+
+ if (obj[i] != exp) {
+ poison_error(pool, element, size, i);
+ return;
+ }
+ }
+ memset(obj, POISON_INUSE, size);
+}
+
+static void check_element(mempool_t *pool, void *element)
+{
+ /* Mempools backed by slab allocator */
+ if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
+ __check_element(pool, element, ksize(element));
+
+ /* Mempools backed by page allocator */
+ if (pool->free == mempool_free_pages) {
+ int order = (int)(long)pool->pool_data;
+ void *addr = kmap_atomic((struct page *)element);
+
+ __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
+ kunmap_atomic(addr);
+ }
+}
+
+static void __poison_element(void *element, size_t size)
+{
+ u8 *obj = element;
+
+ memset(obj, POISON_FREE, size - 1);
+ obj[size - 1] = POISON_END;
+}
+
+static void poison_element(mempool_t *pool, void *element)
+{
+ /* Mempools backed by slab allocator */
+ if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
+ __poison_element(element, ksize(element));
+
+ /* Mempools backed by page allocator */
+ if (pool->alloc == mempool_alloc_pages) {
+ int order = (int)(long)pool->pool_data;
+ void *addr = kmap_atomic((struct page *)element);
+
+ __poison_element(addr, 1UL << (PAGE_SHIFT + order));
+ kunmap_atomic(addr);
+ }
+}
+#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
+static inline void check_element(mempool_t *pool, void *element)
+{
+}
+static inline void poison_element(mempool_t *pool, void *element)
+{
+}
+#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
+
static void add_element(mempool_t *pool, void *element)
{
BUG_ON(pool->curr_nr >= pool->min_nr);
+ poison_element(pool, element);
pool->elements[pool->curr_nr++] = element;
}
static void *remove_element(mempool_t *pool)
{
- BUG_ON(pool->curr_nr <= 0);
- return pool->elements[--pool->curr_nr];
+ void *element = pool->elements[--pool->curr_nr];
+
+ BUG_ON(pool->curr_nr < 0);
+ check_element(pool, element);
+ return element;
}
/**
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