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Date:   Wed, 7 Oct 2020 13:53:16 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Daniel Vetter <daniel.vetter@ffwll.ch>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>, kvm@vger.kernel.org,
        linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org,
        linux-s390@vger.kernel.org,
        Daniel Vetter <daniel.vetter@intel.com>,
        Pawel Osciak <pawel@osciak.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        John Hubbard <jhubbard@nvidia.com>,
        =?utf-8?B?SsOpcsO0bWU=?= Glisse <jglisse@redhat.com>,
        Jan Kara <jack@suse.cz>,
        Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH 05/13] mm/frame-vector: Use FOLL_LONGTERM
Message-ID: <20201007165316.GT5177@ziepe.ca>
References: <20201007164426.1812530-1-daniel.vetter@ffwll.ch>
 <20201007164426.1812530-6-daniel.vetter@ffwll.ch>
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In-Reply-To: <20201007164426.1812530-6-daniel.vetter@ffwll.ch>
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On Wed, Oct 07, 2020 at 06:44:18PM +0200, Daniel Vetter wrote:
>  
> -	/*
> -	 * While get_vaddr_frames() could be used for transient (kernel
> -	 * controlled lifetime) pinning of memory pages all current
> -	 * users establish long term (userspace controlled lifetime)
> -	 * page pinning. Treat get_vaddr_frames() like
> -	 * get_user_pages_longterm() and disallow it for filesystem-dax
> -	 * mappings.
> -	 */
> -	if (vma_is_fsdax(vma)) {
> -		ret = -EOPNOTSUPP;
> -		goto out;
> -	}
> -
> -	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
> -		vec->got_ref = true;
> -		vec->is_pfns = false;
> -		ret = pin_user_pages_locked(start, nr_frames,
> -			gup_flags, (struct page **)(vec->ptrs), &locked);
> -		goto out;
> -	}

The vm_flags still need to be checked before going into the while
loop. If the break is taken then nothing would check vm_flags

Jason