Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK

From	Florian Weimer <fweimer@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK
Date	2017-08-08 17:30 +0200
Message-ID	<uceCe-1Tv-21@gated-at.bofh.it> (permalink)
References	<ubupJ-3f0-29@gated-at.bofh.it> <ubUWR-3Xj-1@gated-at.bofh.it> <uc9sS-6dC-25@gated-at.bofh.it> <uccAp-rl-11@gated-at.bofh.it> <uceCd-1Tv-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 08/08/2017 05:19 PM, Mike Kravetz wrote:
> On 08/08/2017 06:15 AM, Rik van Riel wrote:
>> On Tue, 2017-08-08 at 11:58 +0200, Florian Weimer wrote:
>>> On 08/07/2017 08:23 PM, Mike Kravetz wrote:
>>>> If my thoughts above are correct, what about returning EINVAL if
>>>> one
>>>> attempts to set MADV_DONTFORK on mappings set up for sharing?
>>>
>>> That's my preference as well.  If there is a use case for shared or
>>> non-anonymous mappings, then we can implement MADV_DONTFORK with the
>>> semantics for this use case.  If we pick some arbitrary semantics
>>> now,
>>> without any use case, we might end up with something that's not
>>> actually
>>> useful.
>>
>> MADV_DONTFORK is existing semantics, and it is enforced
>> on shared, non-anonymous mappings. It is frequently used
>> for things like device mappings, which should not be
>> inherited by a child process, because the device can only
>> be used by one process at a time.
>>
>> When someone requests MADV_DONTFORK on a shared VMA, they
>> will get it. The later madvise request overrides the mmap
>> flags that were used earlier.
>>
>> The question is, should MADV_WIPEONFORK (introduced by
>> this series) have not just different semantics, but also
>> totally different behavior from MADV_DONTFORK?
> 
> Sorry for the confusion.  I accidentally used MADV_DONTFORK instead
> of MADV_WIPEONFORK in my reply (which Florian commented on).

Yes, I made the same mistake.  I meant MADV_WIPEONFORK as well.

Florian

Thread

[PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK riel@redhat.com - 2017-08-06 16:10 +0200
  Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-07 15:30 +0200
    Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-07 15:50 +0200
      Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-07 16:20 +0200
        Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 15:10 +0200
      Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-07 17:10 +0200
        Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-08-09 12:10 +0200
          Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-09 14:40 +0200
          Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-09 14:50 +0200
        Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 15:10 +0200
          Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Colm MacCárthaigh <colm@allcosts.net> - 2017-08-10 15:30 +0200
            Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 17:40 +0200
              Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 19:10 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Colm MacCárthaigh <colm@allcosts.net> - 2017-08-11 00:20 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-11 16:10 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-11 16:20 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-11 16:30 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-11 17:30 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-11 17:40 +0200
      Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Colm MacCárthaigh <colm@allcosts.net> - 2017-08-07 18:10 +0200
      Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 15:30 +0200
        Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 16:20 +0200
  Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Mike Kravetz <mike.kravetz@oracle.com> - 2017-08-07 20:30 +0200
    Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-08 12:00 +0200
      Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-08 15:20 +0200
        Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Mike Kravetz <mike.kravetz@oracle.com> - 2017-08-08 17:30 +0200
          Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Florian Weimer <fweimer@redhat.com> - 2017-08-08 17:30 +0200
          Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-08 17:50 +0200
            Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Colm MacCárthaigh <colm@allcosts.net> - 2017-08-08 18:50 +0200
            Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Matthew Wilcox <willy@infradead.org> - 2017-08-08 19:00 +0200
              Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Rik van Riel <riel@redhat.com> - 2017-08-08 20:50 +0200
                Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK Michal Hocko <mhocko@kernel.org> - 2017-08-10 17:40 +0200

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