linux-kernel - Re: [PATCH v9 1/8] mm: Introduce memfd_restricted system call to create restricted user memory

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Date:   Fri, 28 Oct 2022 14:12:32 +0800
From:   Chao Peng <chao.p.peng@...ux.intel.com>
To:     Isaku Yamahata <isaku.yamahata@...il.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...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>, tabba@...gle.com,
        Michael Roth <michael.roth@....com>, mhocko@...e.com,
        Muchun Song <songmuchun@...edance.com>, wei.w.wang@...el.com
Subject: Re: [PATCH v9 1/8] mm: Introduce memfd_restricted system call to
 create restricted user memory

On Wed, Oct 26, 2022 at 10:31:45AM -0700, Isaku Yamahata wrote:
> On Tue, Oct 25, 2022 at 11:13:37PM +0800,
> Chao Peng <chao.p.peng@...ux.intel.com> wrote:
> 
> > +int restrictedmem_get_page(struct file *file, pgoff_t offset,
> > +			   struct page **pagep, int *order)
> > +{
> > +	struct restrictedmem_data *data = file->f_mapping->private_data;
> > +	struct file *memfd = data->memfd;
> > +	struct page *page;
> > +	int ret;
> > +
> > +	ret = shmem_getpage(file_inode(memfd), offset, &page, SGP_WRITE);
> 
> shmem_getpage() was removed.
> https://lkml.kernel.org/r/20220902194653.1739778-34-willy@infradead.org

Thanks for pointing out. My current base(kvm/queue) has not included
this change yet so still use shmem_getpage().

Chao
> 
> I needed the following fix to compile.
> 
> thanks,
> 
> diff --git a/mm/restrictedmem.c b/mm/restrictedmem.c
> index e5bf8907e0f8..4694dd5609d6 100644
> --- a/mm/restrictedmem.c
> +++ b/mm/restrictedmem.c
> @@ -231,13 +231,15 @@ int restrictedmem_get_page(struct file *file, pgoff_t offset,
>  {
>         struct restrictedmem_data *data = file->f_mapping->private_data;
>         struct file *memfd = data->memfd;
> +       struct folio *folio = NULL;
>         struct page *page;
>         int ret;
>  
> -       ret = shmem_getpage(file_inode(memfd), offset, &page, SGP_WRITE);
> +       ret = shmem_get_folio(file_inode(memfd), offset, &folio, SGP_WRITE);
>         if (ret)
>                 return ret;
>  
> +       page = folio_file_page(folio, offset);
>         *pagep = page;
>         if (order)
>                 *order = thp_order(compound_head(page));
> -- 
> Isaku Yamahata <isaku.yamahata@...il.com>