From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick Donnelly <batrick@batbytes.com>
Subject: Re: [PATCH 0/7] userfault21 update
Date: Mon, 12 Oct 2015 11:04:11 -0400
Message-ID: <CACh33FoFK4tbKFgcvN3mBuW7V=pMjM=X7eO68Pp9+56pH4B-EQ@mail.gmail.com>
References: <1434388931-24487-1-git-send-email-aarcange@redhat.com>
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Cc: Andrew Morton <akpm@linux-foundation.org>, open list <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org,
	Pavel Emelyanov <xemul@parallels.com>, Sanidhya Kashyap <sanidhya.gatech@gmail.com>,
	zhang.zhanghailiang@huawei.com,
	Linus Torvalds <torvalds@linux-foundation.org>, "Kirill A. Shutemov" <kirill@shutemov.name>,
	Andres Lagar-Cavilla <andreslc@google.com>, Dave Hansen <dave.hansen@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>, Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
	Andy Lutomirski <luto@amacapital.net>, Hugh Dickins <hughd@google.com>,
	Peter Feiner <pfeiner@google.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>, "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
To: Andrea Arcangeli <aarcange@redhat.com>
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Hello Andrea,

On Mon, Jun 15, 2015 at 1:22 PM, Andrea Arcangeli <aarcange@redhat.com> wrote:
> This is an incremental update to the userfaultfd code in -mm.

Sorry I'm late to this party. I'm curious how a ptrace monitor might
use a userfaultfd to handle faults in all of its tracees. Is this
possible without having each (newly forked) tracee "cooperate" by
creating a userfaultfd and passing that to the tracer?

Have you considered using one userfaultfd for an entire tree of
processes (signaled through a flag)? Would not a process id included
in the include/uapi/linux/userfaultfd.h:struct uffd_msg be sufficient
to disambiguate faults?

-- 
Patrick Donnelly

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