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    SubjectRe: [PATCH 3/4] mm: Add free()
    On Fri, Mar 23, 2018 at 08:14:21AM -0700, Matthew Wilcox wrote:
    > > One more thing, there is
    > > some kasan checks on the main way of kfree(), and there is no guarantee they
    > > reflected in kmem_cache_free() identical.
    >
    > Which function are you talking about here?
    >
    > slub calls slab_free() for both kfree() and kmem_cache_free().
    > slab calls __cache_free() for both kfree() and kmem_cache_free().
    > Each of them do their kasan handling in the called function.

    ... except for where slub can free large objects without calling slab_free():

    if (unlikely(!PageSlab(page))) {
    BUG_ON(!PageCompound(page));
    kfree_hook(object);
    __free_pages(page, compound_order(page));
    return;
    }
    slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);

    If you call kmalloc(16384, GFP_KERNEL), slub will hand back an order-2
    page without setting PageSlab on it. So if that gets passed to free(),
    it'll call __put_page() which calls free_compound_page() which calls
    __free_pages_ok(). Looks like we want another compound_dtor to be sure
    we call the kfree hook.

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