From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Introduce and document a new kasan_mempool_unpoison_pages hook to be used
by the mempool code instead of kasan_unpoison_pages.
This hook is not functionally different from kasan_unpoison_pages, but
using it improves the mempool code readability.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
include/linux/kasan.h | 25 +++++++++++++++++++++++++
mm/kasan/common.c | 6 ++++++
2 files changed, 31 insertions(+)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index de2a695ad34d..f8ebde384bd7 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -225,6 +225,9 @@ bool __kasan_mempool_poison_pages(struct page *page, unsigned int order,
* This function is similar to kasan_mempool_poison_object() but operates on
* page allocations.
*
+ * Before the poisoned allocation can be reused, it must be unpoisoned via
+ * kasan_mempool_unpoison_pages().
+ *
* Return: true if the allocation can be safely reused; false otherwise.
*/
static __always_inline bool kasan_mempool_poison_pages(struct page *page,
@@ -235,6 +238,27 @@ static __always_inline bool kasan_mempool_poison_pages(struct page *page,
return true;
}
+void __kasan_mempool_unpoison_pages(struct page *page, unsigned int order,
+ unsigned long ip);
+/**
+ * kasan_mempool_unpoison_pages - Unpoison a mempool page allocation.
+ * @page: Pointer to the page allocation.
+ * @order: Order of the allocation.
+ *
+ * This function is intended for kernel subsystems that cache page allocations
+ * to reuse them instead of freeing them back to page_alloc (e.g. mempool).
+ *
+ * This function unpoisons a page allocation that was previously poisoned by
+ * kasan_mempool_poison_pages() without zeroing the allocation's memory. For
+ * the tag-based modes, this function assigns a new tag to the allocation.
+ */
+static __always_inline void kasan_mempool_unpoison_pages(struct page *page,
+ unsigned int order)
+{
+ if (kasan_enabled())
+ __kasan_mempool_unpoison_pages(page, order, _RET_IP_);
+}
+
bool __kasan_mempool_poison_object(void *ptr, unsigned long ip);
/**
* kasan_mempool_poison_object - Check and poison a mempool slab allocation.
@@ -353,6 +377,7 @@ static inline bool kasan_mempool_poison_pages(struct page *page, unsigned int or
{
return true;
}
+static inline void kasan_mempool_unpoison_pages(struct page *page, unsigned int order) {}
static inline bool kasan_mempool_poison_object(void *ptr)
{
return true;
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 9ccc78b20cf2..6283f0206ef6 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -439,6 +439,12 @@ bool __kasan_mempool_poison_pages(struct page *page, unsigned int order,
return true;
}
+void __kasan_mempool_unpoison_pages(struct page *page, unsigned int order,
+ unsigned long ip)
+{
+ __kasan_unpoison_pages(page, order, false);
+}
+
bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
{
struct folio *folio;
--
2.25.1
