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:   Mon, 11 Jan 2021 17:24:02 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Will Deacon <will@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Jan Kara <jack@suse.cz>, Minchan Kim <minchan@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Vinayak Menon <vinmenon@codeaurora.org>,
        Hugh Dickins <hughd@google.com>,
        Android Kernel Team <kernel-team@android.com>
Subject: Re: [PATCH v2 0/3] Create 'old' ptes for faultaround mappings on
 arm64 with hardware access flag
Message-ID: <20210111142402.6euyktmcnpemanf7@box>
References: <20210108171517.5290-1-will@kernel.org>
 <CAHk-=wg3UkUdiTbqWFx3zBLXv9VJHuNZAa5QyDvXiSmD4gX94A@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAHk-=wg3UkUdiTbqWFx3zBLXv9VJHuNZAa5QyDvXiSmD4gX94A@mail.gmail.com>
Precedence: bulk

On Fri, Jan 08, 2021 at 11:34:08AM -0800, Linus Torvalds wrote:
> I still dislike how we basically randomly modify the information in
> that 'vmf' thing.

I wounder if it would be acceptable to pass down to faultaround a copy
of vmf, so it mess with it without risking to corrupt the original one?

We would need to transfer back prealloc_pte, but the rest can be safely
discarded, I believe.

But it's somewhat wasteful of stack. sizeof(vmf) == 96 on x86-64.

-- 
 Kirill A. Shutemov