From: Michal Hocko <mhocko@kernel.org>
To: Prakash Sangappa <prakash.sangappa@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Dave Hansen <dave.hansen@intel.com>,
Christoph Hellwig <hch@infradead.org>,
linux-api@vger.kernel.org
Subject: Re: [RFC PATCH] userfaultfd: Add feature to request for a signal delivery
Date: Thu, 29 Jun 2017 10:09:10 +0200 [thread overview]
Message-ID: <20170629080910.GC31603@dhcp22.suse.cz> (raw)
In-Reply-To: <3a8e0042-4c49-3ec8-c59f-9036f8e54621@oracle.com>
On Wed 28-06-17 11:23:32, Prakash Sangappa wrote:
>
>
> On 6/28/17 6:18 AM, Mike Rapoport wrote:
[...]
> >I've just been thinking that maybe it would be possible to use
> >UFFD_EVENT_REMOVE for this case. We anyway need to implement the generation
> >of UFFD_EVENT_REMOVE for the case of hole punching in hugetlbfs for
> >non-cooperative userfaultfd. It could be that it will solve your issue as
> >well.
> >
>
> Will this result in a signal delivery?
>
> In the use case described, the database application does not need any event
> for hole punching. Basically, just a signal for any invalid access to
> mapped area over holes in the file.
OK, but it would be better to think that through for other potential
usecases so that this doesn't end up as a single hugetlb feature. E.g.
what should happen if a regular anonymous memory gets swapped out?
Should we deliver signal as well? How does userspace tell whether this
was a no backing page from unavailable backing page?
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-06-29 8:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-26 19:46 [RFC PATCH] userfaultfd: Add feature to request for a signal delivery Prakash Sangappa
2017-06-27 7:06 ` Michal Hocko
2017-06-27 15:35 ` Mike Rapoport
2017-06-27 16:01 ` Prakash Sangappa
2017-06-28 13:18 ` Mike Rapoport
2017-06-28 18:23 ` Prakash Sangappa
2017-06-29 8:09 ` Michal Hocko [this message]
2017-06-29 21:41 ` prakash.sangappa
2017-06-30 9:47 ` Michal Hocko
2017-06-30 13:08 ` Andrea Arcangeli
2017-07-01 0:55 ` prakash sangappa
2017-07-04 16:40 ` Andrea Arcangeli
2017-07-05 22:24 ` prakash.sangappa
2017-07-05 18:41 ` John Stultz
2017-06-29 10:46 ` Mike Rapoport
2017-06-29 21:49 ` prakash.sangappa
2017-06-27 15:47 ` Prakash Sangappa
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