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Date:   Mon, 13 Jun 2022 14:55:40 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Axel Rasmussen <axelrasmussen@google.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Charan Teja Reddy <charante@codeaurora.org>,
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Subject: Re: [PATCH v3 2/6] userfaultfd: add /dev/userfaultfd for fine
 grained access control
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On Wed,  1 Jun 2022 14:09:47 -0700 Axel Rasmussen <axelrasmussen@google.com> wrote:

> To achieve this, add a /dev/userfaultfd misc device. This device
> provides an alternative to the userfaultfd(2) syscall for the creation
> of new userfaultfds. The idea is, any userfaultfds created this way will
> be able to handle kernel faults, without the caller having any special
> capabilities. Access to this mechanism is instead restricted using e.g.
> standard filesystem permissions.

The use of a /dev node isn't pretty.  Why can't this be done by
tweaking sys_userfaultfd() or by adding a sys_userfaultfd2()?

Peter, will you be completing review of this patchset?