On Sun, 23 Sep 2018, Dmitry Vyukov wrote:

What was the motivation behind that WARNING about large allocations in
kmalloc? Why do we want to know about them? Is the general policy that
kmalloc calls with potentially large size requests need to use NOWARN?
If this WARNING still considered useful? Or we should change it to
pr_err?

In general large allocs should be satisfied by the page allocator. The
slab allocators are used for allocating and managing small objects. The
page allocator has mechanisms to deal with large objects (compound pages,
multiple page sized allocs etc).