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:   Tue, 23 Feb 2021 10:38:40 -0500
From:   Peter Xu <peterx@redhat.com>
To:     Axel Rasmussen <axelrasmussen@google.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Chinwen Chang <chinwen.chang@mediatek.com>,
        Huang Ying <ying.huang@intel.com>,
        Ingo Molnar <mingo@redhat.com>, Jann Horn <jannh@google.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Lokesh Gidra <lokeshgidra@google.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Michal =?utf-8?Q?Koutn=C3=BD?= <mkoutny@suse.com>,
        Michel Lespinasse <walken@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@gmail.com>, Shaohua Li <shli@fb.com>,
        Shawn Anastasio <shawn@anastas.io>,
        Steven Rostedt <rostedt@goodmis.org>,
        Steven Price <steven.price@arm.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        Adam Ruprecht <ruprecht@google.com>,
        Cannon Matthews <cannonmatthews@google.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Mina Almasry <almasrymina@google.com>,
        Oliver Upton <oupton@google.com>
Subject: Re: [PATCH v7 4/6] userfaultfd: add UFFDIO_CONTINUE ioctl
Message-ID: <20210223153840.GB154711@xz-x1>
References: <20210219004824.2899045-1-axelrasmussen@google.com>
 <20210219004824.2899045-5-axelrasmussen@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20210219004824.2899045-5-axelrasmussen@google.com>
Precedence: bulk

On Thu, Feb 18, 2021 at 04:48:22PM -0800, Axel Rasmussen wrote:
> @@ -4645,8 +4646,18 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
>  	spinlock_t *ptl;
>  	int ret;
>  	struct page *page;
> +	int writable;
>  
> -	if (!*pagep) {
> +	mapping = dst_vma->vm_file->f_mapping;
> +	idx = vma_hugecache_offset(h, dst_vma, dst_addr);
> +
> +	if (is_continue) {
> +		ret = -EFAULT;
> +		page = find_lock_page(mapping, idx);
> +		*pagep = NULL;

Why set *pagep to NULL?  Shouldn't it be NULL always?.. If that's the case,
maybe WARN_ON_ONCE(*pagep) suite more.

Otherwise the patch looks good to me.

Thanks,

-- 
Peter Xu