Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 18 Feb 2021 15:41:03 -0500
From:   Peter Xu <peterx@redhat.com>
To:     Axel Rasmussen <axelrasmussen@google.com>
Cc:     Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 4/4] hugetlb/userfaultfd: Unshare all pmds for
 hugetlbfs when register wp
Message-ID: <20210218204103.GF108961@xz-x1>
References: <20210217204418.54259-1-peterx@redhat.com>
 <20210217204619.54761-1-peterx@redhat.com>
 <20210217204619.54761-3-peterx@redhat.com>
 <CAJHvVchtVtDHE2iJRAmraL+kbTezgfck0Mgj7xM+7U5yaJ5aCQ@mail.gmail.com>
 <20210218203214.GD108961@xz-x1>
 <CAJHvVch79WBzudS7BU5Lg2et4_2XQM=mEdW=YpbyX1QHHp=tQg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <CAJHvVch79WBzudS7BU5Lg2et4_2XQM=mEdW=YpbyX1QHHp=tQg@mail.gmail.com>
Precedence: bulk

On Thu, Feb 18, 2021 at 12:34:55PM -0800, Axel Rasmussen wrote:
> On Thu, Feb 18, 2021 at 12:32 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Thu, Feb 18, 2021 at 10:32:00AM -0800, Axel Rasmussen wrote:
> > > > @@ -1448,6 +1449,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
> > > >                 vma->vm_flags = new_flags;
> > > >                 vma->vm_userfaultfd_ctx.ctx = ctx;
> > > >
> > > > +               if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma))
> > > > +                       hugetlb_unshare_all_pmds(vma);
> > >
> > > This line yields the following error, if building with:
> > > # CONFIG_CMA is not set
> > >
> > > ./fs/userfaultfd.c:1459: undefined reference to `hugetlb_unshare_all_pmds'
> >
> > Ouch..  Axel, you mean CONFIG_HUGETLBFS rather than CONFIG_CMA, am I right?
> 
> Surprisingly no, there's a "#ifdef CONFIG_CMA" line ~100 lines above
> where hugetlb_unshare_all_pmds is defined in hugetlb.c which causes
> this. My guess is that putting the function inside that block was
> accidental and it can just be moved.

Right, thanks for catching that, I actually need to fix both.  Thanks,

-- 
Peter Xu