#include <linux/jhash.h>
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/printk.h>
#include <linux/slab.h>
}
early_param("stack_depot_disable", is_stack_depot_disabled);
-int __init stack_depot_init(void)
+/*
+ * __ref because of memblock_alloc(), which will not be actually called after
+ * the __init code is gone, because at that point slab_is_available() is true
+ */
+__ref int stack_depot_init(void)
{
- if (!stack_depot_disable) {
+ static DEFINE_MUTEX(stack_depot_init_mutex);
+
+ mutex_lock(&stack_depot_init_mutex);
+ if (!stack_depot_disable && !stack_table) {
size_t size = (STACK_HASH_SIZE * sizeof(struct stack_record *));
int i;
- stack_table = memblock_alloc(size, size);
- for (i = 0; i < STACK_HASH_SIZE; i++)
- stack_table[i] = NULL;
+ if (slab_is_available()) {
+ pr_info("Stack Depot allocating hash table with kvmalloc\n");
+ stack_table = kvmalloc(size, GFP_KERNEL);
+ } else {
+ pr_info("Stack Depot allocating hash table with memblock_alloc\n");
+ stack_table = memblock_alloc(size, SMP_CACHE_BYTES);
+ }
+ if (stack_table) {
+ for (i = 0; i < STACK_HASH_SIZE; i++)
+ stack_table[i] = NULL;
+ } else {
+ pr_err("Stack Depot hash table allocation failed, disabling\n");
+ stack_depot_disable = true;
+ mutex_unlock(&stack_depot_init_mutex);
+ return -ENOMEM;
+ }
}
+ mutex_unlock(&stack_depot_init_mutex);
return 0;
}
+EXPORT_SYMBOL_GPL(stack_depot_init);
/* Calculate hash for a stack */
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
* (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids
* any allocations and will fail if no space is left to store the stack trace.
*
+ * If the stack trace in @entries is from an interrupt, only the portion up to
+ * interrupt entry is saved.
+ *
* Context: Any context, but setting @can_alloc to %false is required if
* alloc_pages() cannot be used from the current context. Currently
* this is the case from contexts where neither %GFP_ATOMIC nor
unsigned long flags;
u32 hash;
+ /*
+ * If this stack trace is from an interrupt, including anything before
+ * interrupt entry usually leads to unbounded stackdepot growth.
+ *
+ * Because use of filter_irq_stacks() is a requirement to ensure
+ * stackdepot can efficiently deduplicate interrupt stacks, always
+ * filter_irq_stacks() to simplify all callers' use of stackdepot.
+ */
+ nr_entries = filter_irq_stacks(entries, nr_entries);
+
if (unlikely(nr_entries == 0) || stack_depot_disable)
goto fast_exit;