From: Pavel Emelyanov <xemul@virtuozzo.com>
To: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
lkml <linux-kernel@vger.kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Andrei Vagin <avagin@virtuozzo.com>
Subject: Re: [PATCH] userfaultfd: prevent non-cooperative events vs mcopy_atomic races
Date: Fri, 25 May 2018 17:05:42 +0300 [thread overview]
Message-ID: <30794a36-ea91-c941-f59e-6545816a2265@virtuozzo.com> (raw)
In-Reply-To: <20180524190639.GD16908@rapoport-lnx>
>> But doesn't it race even with regular PF handling, not only the fork? How
>> do we handle this race?
>
> With the regular #PF handing, the faulting thread patiently waits until
> page fault is resolved. With fork(), mremap() etc the thread that caused
> the event resumes once the uffd message is read by the monitor. That's
> surely way before monitor had chance to somehow process that message.
Ouch, yes. This is nasty :( So having no better solution in mind, let's
move forward with this.
Acked-by: Pavel Emelyanov <xemul@virtuozzo.com>
next prev parent reply other threads:[~2018-05-25 14:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-23 7:42 Mike Rapoport
2018-05-24 11:24 ` Pavel Emelyanov
2018-05-24 11:56 ` Mike Rapoport
2018-05-24 16:40 ` Pavel Emelyanov
2018-05-24 19:06 ` Mike Rapoport
2018-05-25 14:05 ` Pavel Emelyanov [this message]
2020-12-03 19:57 ` Nadav Amit
2020-12-06 9:37 ` Mike Rapoport
2020-12-07 4:31 ` Nadav Amit
2020-12-08 8:34 ` Mike Rapoport
2020-12-08 8:57 ` Nadav Amit
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