linux-kernel - Re: [PATCH v8 1/8] mm/memfd: Introduce userspace inaccessible memfd

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Date:   Thu, 6 Oct 2022 16:04:08 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Fuad Tabba <tabba@...gle.com>
Cc:     Chao Peng <chao.p.peng@...ux.intel.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-doc@...r.kernel.org, qemu-devel@...gnu.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        Hugh Dickins <hughd@...gle.com>,
        Jeff Layton <jlayton@...nel.org>,
        "J . Bruce Fields" <bfields@...ldses.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>, Mike Rapoport <rppt@...nel.org>,
        Steven Price <steven.price@....com>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        luto@...nel.org, jun.nakajima@...el.com, dave.hansen@...el.com,
        ak@...ux.intel.com, david@...hat.com, aarcange@...hat.com,
        ddutile@...hat.com, dhildenb@...hat.com,
        Quentin Perret <qperret@...gle.com>,
        Michael Roth <michael.roth@....com>, mhocko@...e.com,
        Muchun Song <songmuchun@...edance.com>, wei.w.wang@...el.com
Subject: Re: [PATCH v8 1/8] mm/memfd: Introduce userspace inaccessible memfd

On Thu, Oct 06, 2022 at 09:50:28AM +0100, Fuad Tabba wrote:
> Hi,
> 
> <...>
> 
> 
> > diff --git a/mm/memfd_inaccessible.c b/mm/memfd_inaccessible.c
> > new file mode 100644
> > index 000000000000..2d33cbdd9282
> > --- /dev/null
> > +++ b/mm/memfd_inaccessible.c
> 
> <...>
> 
> > +struct file *memfd_mkinaccessible(struct file *memfd)
> > +{
> > +       struct inaccessible_data *data;
> > +       struct address_space *mapping;
> > +       struct inode *inode;
> > +       struct file *file;
> > +
> > +       data = kzalloc(sizeof(*data), GFP_KERNEL);
> > +       if (!data)
> > +               return ERR_PTR(-ENOMEM);
> > +
> > +       data->memfd = memfd;
> > +       mutex_init(&data->lock);
> > +       INIT_LIST_HEAD(&data->notifiers);
> > +
> > +       inode = alloc_anon_inode(inaccessible_mnt->mnt_sb);
> > +       if (IS_ERR(inode)) {
> > +               kfree(data);
> > +               return ERR_CAST(inode);
> > +       }
> > +
> > +       inode->i_mode |= S_IFREG;
> > +       inode->i_op = &inaccessible_iops;
> > +       inode->i_mapping->private_data = data;
> > +
> > +       file = alloc_file_pseudo(inode, inaccessible_mnt,
> > +                                "[memfd:inaccessible]", O_RDWR,
> > +                                &inaccessible_fops);
> > +       if (IS_ERR(file)) {
> > +               iput(inode);
> > +               kfree(data);
> 
> I think this might be missing a return at this point.

Good catch! Thanks!

-- 
  Kiryl Shutsemau / Kirill A. Shutemov