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From: Peter Xu <peterx@redhat.com>
To: Xiaoming Ni <nixiaoming@huawei.com>
Cc: aarcange@redhat.com, akpm@linux-foundation.org,
	cracauer@cons.org, dplotnikov@virtuozzo.com, gokhale2@llnl.gov,
	hannes@cmpxchg.org, hughd@google.com, jglisse@redhat.com,
	kirill@shutemov.name, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, maxime.coquelin@redhat.com,
	mcfadden8@llnl.gov, mcgrof@kernel.org, mgorman@suse.de,
	mike.kravetz@oracle.com, pbonzini@redhat.com,
	rppt@linux.vnet.ibm.com, xemul@virtuozzo.com,
	keescook@chromium.org
Subject: Re: [PATCH v2 1/1] userfaultfd/sysctl: add vm.unprivileged_userfaultfd
Date: Wed, 27 May 2020 10:21:43 -0400	[thread overview]
Message-ID: <20200527142143.GC1194141@xz-x1> (raw)
In-Reply-To: <3b64de85-beb4-5a07-0093-cad6e8f2a8d8@huawei.com>

On Wed, May 27, 2020 at 02:54:13PM +0800, Xiaoming Ni wrote:
> 
> On Tue, Mar 19, 2019 at 11:07:22AM +0800, Peter Xu wrote:
> > Add a global sysctl knob "vm.unprivileged_userfaultfd" to control
> > whether userfaultfd is allowed by unprivileged users.  When this is
> > set to zero, only privileged users (root user, or users with the
> > CAP_SYS_PTRACE capability) will be able to use the userfaultfd
> > syscalls.
> 
> Hello

Hi, Xiaoming,

> I am a bit confused about this patch, can you help to answer it.
> 
> Why the sysctl interface of fs/userfaultfd.c belongs to vm_table instead of
> fs_table ?
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cefdca0a86be517bc390fc4541e3674b8e7803b0

Because I think it makes more sense to put the new key into where it suites
better, irrelevant to which directory the variable is declared.  To me,
unprivileged_userfaultfd is definitely more suitable for vm rather than fs,
because userfaultfd is really about memory management rather than file system.

Thanks,

-- 
Peter Xu


  reply	other threads:[~2020-05-27 14:21 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27  6:54 [PATCH v2 1/1] userfaultfd/sysctl: add vm.unprivileged_userfaultfd Xiaoming Ni
2020-05-27 14:21 ` Peter Xu [this message]
2020-05-28  8:50   ` Xiaoming Ni
2020-05-28 12:49     ` Peter Xu
  -- strict thread matches above, loose matches on Subject: below --
2019-03-19  3:07 [PATCH v2 0/1] userfaultfd: allow to forbid unprivileged users Peter Xu
2019-03-19  3:07 ` [PATCH v2 1/1] userfaultfd/sysctl: add vm.unprivileged_userfaultfd Peter Xu
2019-03-19  3:07   ` Peter Xu
2019-03-19  7:11   ` Mike Rapoport
2019-03-19  7:11     ` Mike Rapoport
2019-03-19 18:07     ` Andrea Arcangeli
2019-03-19 18:07       ` Andrea Arcangeli
2019-03-19 18:02   ` Andrew Morton
2019-03-19 18:02     ` Andrew Morton
2019-03-19 18:28     ` Dr. David Alan Gilbert
2019-03-19 18:28       ` Dr. David Alan Gilbert
2019-03-20  0:20       ` Peter Xu
2019-03-20  0:20         ` Peter Xu
2019-03-20 19:01       ` Andrea Arcangeli
2019-03-20 19:01         ` Andrea Arcangeli
2019-03-21 13:43         ` Luis Chamberlain
2019-03-21 13:43           ` Luis Chamberlain
2019-03-21 21:06           ` Andrea Arcangeli
2019-03-21 21:06             ` Andrea Arcangeli
2019-04-23 22:19     ` Kees Cook
2019-04-23 22:19       ` Kees Cook
2019-04-23 22:19       ` Kees Cook

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