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From:   =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <emmir@google.com>
Date:   Wed, 21 Jun 2023 16:27:34 +0200
Message-ID: <CABb0KFFsHEX2cKzQj-t9vx=q4FjmObNu930ogQMBn0L6=3ph=w@mail.gmail.com>
Subject: Re: [PATCH v20 2/5] fs/proc/task_mmu: Implement IOCTL to get and
 optionally clear info about PTEs
To:     Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc:     Peter Xu <peterx@redhat.com>, David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrei Vagin <avagin@gmail.com>,
        Danylo Mocherniuk <mdanylo@google.com>,
        Paul Gofman <pgofman@codeweavers.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Mike Rapoport <rppt@kernel.org>, Nadav Amit <namit@vmware.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Shuah Khan <shuah@kernel.org>,
        Christian Brauner <brauner@kernel.org>,
        Yang Shi <shy828301@gmail.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Liam R . Howlett" <Liam.Howlett@oracle.com>,
        Yun Zhou <yun.zhou@windriver.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Alex Sierra <alex.sierra@amd.com>,
        Matthew Wilcox <willy@infradead.org>,
        Pasha Tatashin <pasha.tatashin@soleen.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        "Gustavo A . R . Silva" <gustavoars@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
        Greg KH <gregkh@linuxfoundation.org>, kernel@collabora.com
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On Wed, 21 Jun 2023 at 16:16, Muhammad Usama Anjum
<usama.anjum@collabora.com> wrote:
> On 6/21/23 6:42=E2=80=AFPM, Micha=C5=82 Miros=C5=82aw wrote:
> > On Wed, 21 Jun 2023 at 09:24, Muhammad Usama Anjum
> > <usama.anjum@collabora.com> wrote:
> > [...]
> >> +static int pagemap_scan_test_walk(unsigned long start, unsigned long =
end,
> >> +                                 struct mm_walk *walk)
> >> +{
> >> +       struct pagemap_scan_private *p =3D walk->private;
> >> +       struct vm_area_struct *vma =3D walk->vma;
> >> +
> >> +       if ((p->flags & PM_SCAN_REQUIRE_UFFD) && (!userfaultfd_wp_asyn=
c(vma) ||
> >> +           !userfaultfd_wp_use_markers(vma)))
> >> +               return -EPERM;
> >> +
> >> +       if (vma->vm_flags & VM_PFNMAP)
> >> +               return 1;
> >> +
> >> +       return 0;
> >> +}
> >
> > This could actually short-circuit all vma flags (e.g. IS_FILE): if
> > (required_mask & IS_FILE && vma is not file-backed) return 0;
> Sorry, unable to understand you. Should we do something here?

It seems I had an earlier version of the patch in my mind, where
PAGE_IS_FILE was based on vma type. Sorry for the noise.

Best Regards
Micha=C5=82 Miros=C5=82aw

>
> >
> > Best Regards
> > Micha=C5=82 Miros=C5=82aw
>
> --
> BR,
> Muhammad Usama Anjum