Re: [PATCH 1/6] mm: introduce kv[mz]alloc helpers

[Vlastimil Babka]

On 01/26/2017 01:09 PM, Michal Hocko wrote:
> On Thu 12-01-17 16:37:12, Michal Hocko wrote:
> [...]
> > +void *kvmalloc_node(size_t size, gfp_t flags, int node)
> > +{
> > +	gfp_t kmalloc_flags = flags;
> > +	void *ret;
> > +
> > +	/*
> > +	 * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
> > +	 * so the given set of flags has to be compatible.
> > +	 */
> > +	WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
> > +
> > +	/*
> > +	 * Make sure that larger requests are not too disruptive - no OOM
> > +	 * killer and no allocation failure warnings as we have a fallback
> > +	 */
> > +	if (size > PAGE_SIZE)
> > +		kmalloc_flags |= __GFP_NORETRY | __GFP_NOWARN;
> > +
> > +	ret = kmalloc_node(size, kmalloc_flags, node);
> > +
> > +	/*
> > +	 * It doesn't really make sense to fallback to vmalloc for sub page
> > +	 * requests
> > +	 */
> > +	if (ret || size <= PAGE_SIZE)
> > +		return ret;
> > +
> > +	return __vmalloc_node_flags(size, node, flags);
> > +}
> > +EXPORT_SYMBOL(kvmalloc_node);
>
> While discussing bpf change I've realized that the vmalloc fallback
> doesn't request __GFP_HIGHMEM. So I've updated the patch to do so. All
> the current users except for f2fs_kv[zm]alloc which just seemed to
> forgot or didn't know about the flag. In the next step, I would like to
> check whether we actually have any __vmalloc* user which would strictly
> refuse __GFP_HIGHMEM because I do not really see any reason for that and
> if there is none then I would simply pull __GFP_HIGHMEM handling into
> the vmalloc.
>
> So before I resend the full series again, can I keep acks with the
> following?

OK!

Thanks,
Vlastimil