On Tue, Aug 30, 2016 at 11:23:36AM -0700, Linus Torvalds wrote:
> On Tue, Aug 30, 2016 at 4:48 AM, Jeff Layton <[email protected]> wrote:
> >
> > While this would be good to get in, I don't see any particular urgency
> > here. This seems like it'd be reasonable for v4.9.
>
> Agreed, looks ok to me. It certainly does not look like a new
> regression or like a serious problem issue in practice. So 4.9 sounds
> appropriate.
Gah, Jeff points out I forgot to merge this.
Jeff was also wondering whether we could instead just allocate this with
vmalloc--is there any drawback? We only allocate this on nfsd startup,
so if the only drawback is the allocation itself being expensive then
that's no big deal.
--b.
On Thu, Oct 20, 2016 at 8:52 AM, Bruce Fields <[email protected]> wrote:
>
> Jeff was also wondering whether we could instead just allocate this with
> vmalloc--is there any drawback? We only allocate this on nfsd startup,
> so if the only drawback is the allocation itself being expensive then
> that's no big deal.
vmalloc is ok. Generally if it's *usually* a small allocation, the
best pattern tends to be to first try to kmalloc (of get_free_pages())
using __GFP_NORETRY | __GFP_NOWARN, and then fall back on vmalloc().
That way you don't end up doing vmalloc's for things that really don't
need it.
If you do that, we have a "kvfree()" helper that is "free either
kmalloc or vmalloc area", so you don't have to track after-the-fact
which one you did.
Linus