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Date: Mon, 1 Dec 2014 10:36:04 -0800
Message-ID: <CA+55aFz+ODi34J2n0kzXm+v++B7KW1e9NSFU=f-jgonPA1bNxg@mail.gmail.com>
Subject: Re: frequent lockups in 3.18rc4
From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Will Deacon <will.deacon@arm.com>, Tejun Heo <tj@kernel.org>,
        Dave Jones <davej@redhat.com>, Andy Lutomirski <luto@amacapital.net>,
        Don Zickus <dzickus@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Mon, Dec 1, 2014 at 10:25 AM, Kirill A. Shutemov
<kirill@shutemov.name> wrote:
>
> No idea about oom_score, but kernel happily accepts chmod on any file
> under /proc/PID/net/.

/proc used to accept that fairly widely, but no, we tightened things
down, and core /proc files end up not accepting chmod. See
'proc_setattr()':

        if (attr->ia_valid & ATTR_MODE)
                return -EPERM;

although particular /proc files could choose to not use 'proc_setattr'
if they want to.

The '/proc/pid/net' subtree is obviously not doing that. No idea why,
and probably for no good reason.

                     Linus
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