On Thu, 18 Oct 2012, Ezequiel Garcia wrote: > 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 Penberg <[email protected]>
Is Pekka Penberg the long distant cousin of Pekka Enberg? :) You should probably cc the author of slob, Matt Mackall <[email protected]>, on slob patches. > Acked-by: Christoph Lameter <[email protected]> > Signed-off-by: Ezequiel Garcia <[email protected]> > --- > mm/slob.c | 24 ++++++++++-------------- > 1 files changed, 10 insertions(+), 14 deletions(-) > > diff --git a/mm/slob.c b/mm/slob.c > index a08e468..06a5ec7 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 > @@ -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); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
