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Date:   Tue, 27 Apr 2021 17:02:25 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Axel Rasmussen <axelrasmussen@google.com>
cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Joe Perches <joe@perches.com>,
        Lokesh Gidra <lokeshgidra@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Peter Xu <peterx@redhat.com>, Shaohua Li <shli@fb.com>,
        Shuah Khan <shuah@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Wang Qing <wangqing@vivo.com>, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        Brian Geffon <bgeffon@google.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        Mina Almasry <almasrymina@google.com>,
        Oliver Upton <oupton@google.com>
Subject: Re: [PATCH v5 03/10] userfaultfd/shmem: support minor fault registration
 for shmem
In-Reply-To: <20210427225244.4326-4-axelrasmussen@google.com>
Message-ID: <alpine.LSU.2.11.2104271701500.7111@eggly.anvils>
References: <20210427225244.4326-1-axelrasmussen@google.com> <20210427225244.4326-4-axelrasmussen@google.com>
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On Tue, 27 Apr 2021, Axel Rasmussen wrote:

> This patch allows shmem-backed VMAs to be registered for minor faults.
> Minor faults are appropriately relayed to userspace in the fault path,
> for VMAs with the relevant flag.
> 
> This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed
> minor faults, though, so userspace doesn't yet have a way to resolve
> such faults.
> 
> Because of this, we also don't yet advertise this as a supported
> feature. That will be done in a separate commit when the feature is
> fully implemented.
> 
> Acked-by: Peter Xu <peterx@redhat.com>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>

Acked-by: Hugh Dickins <hughd@google.com>

> ---
>  fs/userfaultfd.c |  3 +--
>  mm/memory.c      |  8 +++++---
>  mm/shmem.c       | 12 +++++++++++-
>  3 files changed, 17 insertions(+), 6 deletions(-)