From: Andrew Morton <akpm@linux-foundation.org>
To: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
linux-mm <linux-mm@kvack.org>,
linux-api <linux-api@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>, crml <criu@openvz.org>
Subject: Re: [PATCH 0/3] userfaultfd: non-cooperative: syncronous events
Date: Fri, 2 Mar 2018 15:38:49 -0800 [thread overview]
Message-ID: <20180302153849.d9d7b9a873755c6f5e883d0d@linux-foundation.org> (raw)
In-Reply-To: <1519719592-22668-1-git-send-email-rppt@linux.vnet.ibm.com>
On Tue, 27 Feb 2018 10:19:49 +0200 Mike Rapoport <rppt@linux.vnet.ibm.com> wrote:
> Hi,
>
> These patches add ability to generate userfaultfd events so that their
> processing will be synchronized with the non-cooperative thread that caused
> the event.
>
> In the non-cooperative case userfaultfd resumes execution of the thread
> that caused an event when the notification is read() by the uffd monitor.
> In some cases, like, for example, madvise(MADV_REMOVE), it might be
> desirable to keep the thread that caused the event suspended until the
> uffd monitor had the event handled to avoid races between the thread that
> caused the and userfaultfd ioctls.
>
> Theses patches extend the userfaultfd API with an implementation of
> UFFD_EVENT_REMOVE_SYNC that allows to keep the thread that triggered
> UFFD_EVENT_REMOVE until the uffd monitor would not wake it explicitly.
"might be desirable" is a bit weak. It might not be desirable, too ;)
_Is_ it desirable? What are the use-cases and what is the end-user
benefit?
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next prev parent reply other threads:[~2018-03-02 23:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 8:19 Mike Rapoport
2018-02-27 8:19 ` [PATCH 1/3] userfaultfd: introduce userfaultfd_init_waitqueue helper Mike Rapoport
2018-02-27 8:19 ` [PATCH 2/3] userfaultfd: non-cooperative: generalize wake key structure Mike Rapoport
2018-02-27 8:19 ` [PATCH 3/3] userfaultfd: non-cooperative: allow synchronous EVENT_REMOVE Mike Rapoport
2018-02-28 8:21 ` Pavel Emelyanov
2018-02-28 8:26 ` Mike Rapoport
2018-03-02 23:38 ` Andrew Morton [this message]
2018-03-03 9:09 ` [PATCH 0/3] userfaultfd: non-cooperative: syncronous events Mike Rapoport
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