This field was being used to store size allocation so it could be
retrieved by ksize(). However, it is a bad practice to not mark a page
as a slab page and then use fields for special purposes.
There is no need to store the allocated size and
ksize() can simply return PAGE_SIZE << compound_order(page).
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxxxxx>
Signed-off-by: Ezequiel Garcia <elezegarcia@xxxxxxxxx>
---
mm/slob.c | 23 ++++++++++-------------
1 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/mm/slob.c b/mm/slob.c
index 686e98b..987da93 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -28,9 +28,8 @@
* from kmalloc are prepended with a 4-byte header with the kmalloc size.
* If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
* alloc_pages() directly, allocating compound pages so the page order
- * does not have to be separately tracked, and also stores the exact
- * allocation size in page->private so that it can be used to accurately
- * provide ksize(). These objects are detected in kfree() because slob_page()
+ * does not have to be separately tracked.
+ * These objects are detected in kfree() because PageSlab()
* is false for them.
*
* SLAB is emulated on top of SLOB by simply calling constructors and
@@ -450,7 +449,6 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node)
size, size + align, gfp, node);
} else {
unsigned int order = get_order(size);
- struct page *page;
if (likely(order))
gfp |= __GFP_COMP;
@@ -458,9 +456,6 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node)
if (!ret)
return NULL;
- page = virt_to_page(ret);
- page->private = size;
-
trace_kmalloc_node(_RET_IP_, ret,
size, PAGE_SIZE << order, gfp, node);
}
@@ -494,18 +489,20 @@ EXPORT_SYMBOL(kfree);
size_t ksize(const void *block)
{
struct page *sp;
+ int align;
+ unsigned int *m;
BUG_ON(!block);
if (unlikely(block == ZERO_SIZE_PTR))
return 0;
sp = virt_to_page(block);
- if (PageSlab(sp)) {
- int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
- unsigned int *m = (unsigned int *)(block - align);
- return SLOB_UNITS(*m) * SLOB_UNIT;
- } else
- return sp->private;
+ if (unlikely(!PageSlab(sp)))
+ return PAGE_SIZE << compound_order(sp);
+
+ align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+ m = (unsigned int *)(block - align);
+ return SLOB_UNITS(*m) * SLOB_UNIT;
}
EXPORT_SYMBOL(ksize);
--
1.7.8.6
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