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mm/slob: Drop usage of page->private for storing page-sized allocations 

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@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
hifive-unleashed-5.1
Ezequiel Garcia 2012-10-19 09:33:10 -03:00 committed by Pekka Enberg
parent 1b4f59e356
commit 999d8795d4
1 changed files with 10 additions and 14 deletions
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24
mm/slob.c
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@ -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
@ -455,11 +454,6 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
if (likely(order))
gfp |= __GFP_COMP;
ret = slob_new_pages(gfp, order, node);
if (ret) {
struct page *page;
page = virt_to_page(ret);
page->private = size;
}
trace_kmalloc_node(caller, ret,
size, PAGE_SIZE << order, gfp, node);
@ -514,18 +508,20 @@ 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);