Re: [PATCH] dax: Change return type to vm_fault_t

From: Matthew Wilcox <willy@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Linux MM <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] dax: Change return type to vm_fault_t
Date: Mon, 16 Apr 2018 11:21:46 -0700	[thread overview]
Message-ID: <20180416182146.GC12686@bombadil.infradead.org> (raw)
In-Reply-To: <CAPcyv4hUsADs9ueDfLKvcqHvz3Z4ziW=a1V6rkcOtTvoJhw7xg@mail.gmail.com>

On Mon, Apr 16, 2018 at 11:00:26AM -0700, Dan Williams wrote:
> On Mon, Apr 16, 2018 at 10:47 AM, Matthew Wilcox <willy@infradead.org> wrote:
> > On Mon, Apr 16, 2018 at 09:14:48AM -0700, Dan Williams wrote:
> >> > -       rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
> >> > -
> >> > -       if (rc == -ENOMEM)
> >> > -               return VM_FAULT_OOM;
> >> > -       if (rc < 0 && rc != -EBUSY)
> >> > -               return VM_FAULT_SIGBUS;
> >> > -
> >> > -       return VM_FAULT_NOPAGE;
> >> > +       return vmf_insert_mixed(vmf->vma, vmf->address, pfn);
> >>
> >> Ugh, so this change to vmf_insert_mixed() went upstream without fixing
> >> the users? This changelog is now misleading as it does not mention
> >> that is now an urgent standalone fix. On first read I assumed this was
> >> part of a wider effort for 4.18.
> >
> > You read too quickly.  vmf_insert_mixed() is a *new* function which
> > *replaces* vm_insert_mixed() and
> > awful-mangling-of-return-values-done-per-driver.
> >
> > Eventually vm_insert_mixed() will be deleted.  But today is not that day.
> 
> Ah, ok, thanks for the clarification. Then this patch should
> definitely be re-titled to "dax: convert to the new vmf_insert_mixed()
> helper". The vm_fault_t conversion is just a minor side-effect of that
> larger change. I assume this can wait for v4.18.

Yes, no particular hurry.