From: Dmitry Vyukov <dvyukov@google.com>
Subject: Re: SLAB_TYPESAFE_BY_RCU without constructors (was Re: [PATCH v4
 13/17] khwasan: add hooks implementation)
Date: Wed, 1 Aug 2018 12:34:54 +0200
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Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        "Theodore Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.com>,
        linux-ext4@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>,
        David Miller <davem@davemloft.net>,
        NetFilter <netfilter-devel@vger.kernel.org>,
        coreteam@netfilter.org,
        Network Development <netdev@vger.kernel.org>,
        Gerrit Renker <gerrit@erg.abdn.ac.uk>, dccp@vger.kernel.org,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Dave Airlie <airlied@linux.ie>,
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Wed, Aug 1, 2018 at 12:23 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On 08/01/2018 02:03 AM, Andrey Ryabinin wrote:
>
>> I can't think of any advantage in not having the constructor.
>
> I can't see any advantage adding another indirect call,
> in RETPOLINE world.

Can you please elaborate what's the problem here?
If slab ctor call have RETPOLINE, then using ctors more does not
introduce any security problems and they are not _that_ slow.
If slab ctors are not protected, then we have problem that needs to be
fixed already.
What am I missing?