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>
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1b4f59e356
Коммит
999d8795d4
24
mm/slob.c
24
mm/slob.c
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@ -28,9 +28,8 @@
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* from kmalloc are prepended with a 4-byte header with the kmalloc size.
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* If kmalloc is asked for objects of PAGE_SIZE or larger, it calls
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* alloc_pages() directly, allocating compound pages so the page order
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* does not have to be separately tracked, and also stores the exact
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* allocation size in page->private so that it can be used to accurately
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* provide ksize(). These objects are detected in kfree() because slob_page()
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* does not have to be separately tracked.
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* These objects are detected in kfree() because PageSlab()
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* is false for them.
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*
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* SLAB is emulated on top of SLOB by simply calling constructors and
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@ -455,11 +454,6 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
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if (likely(order))
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gfp |= __GFP_COMP;
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ret = slob_new_pages(gfp, order, node);
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if (ret) {
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struct page *page;
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page = virt_to_page(ret);
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page->private = size;
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}
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trace_kmalloc_node(caller, ret,
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size, PAGE_SIZE << order, gfp, node);
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@ -514,18 +508,20 @@ EXPORT_SYMBOL(kfree);
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size_t ksize(const void *block)
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{
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struct page *sp;
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int align;
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unsigned int *m;
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BUG_ON(!block);
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if (unlikely(block == ZERO_SIZE_PTR))
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return 0;
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sp = virt_to_page(block);
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if (PageSlab(sp)) {
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int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
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unsigned int *m = (unsigned int *)(block - align);
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return SLOB_UNITS(*m) * SLOB_UNIT;
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} else
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return sp->private;
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if (unlikely(!PageSlab(sp)))
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return PAGE_SIZE << compound_order(sp);
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align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
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m = (unsigned int *)(block - align);
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return SLOB_UNITS(*m) * SLOB_UNIT;
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}
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EXPORT_SYMBOL(ksize);
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