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Subject: Re: [PATCH 1/3] mm: get_cmdline use arg_lock instead of mmap_sem
To:     Cyrill Gorcunov <gorcunov@gmail.com>
Cc:     =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>,
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        mguzik@redhat.com, mhocko@kernel.org, rppt@linux.ibm.com,
        vbabka@suse.cz
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From:   Kirill Tkhai <ktkhai@virtuozzo.com>
Message-ID: <1a7265fa-610b-1f2a-e55f-b3a307a39bf2@virtuozzo.com>
Date:   Tue, 30 Apr 2019 12:53:51 +0300
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On 30.04.2019 12:38, Cyrill Gorcunov wrote:
> On Tue, Apr 30, 2019 at 12:09:57PM +0300, Kirill Tkhai wrote:
>>
>> This looks OK for me.
>>
>> But speaking about existing code it's a secret for me, why we ignore arg_lock
>> in binfmt code, e.g. in load_elf_binary().
> 
> Well, strictly speaking we probably should but you know setup of
> the @arg_start by kernel's elf loader doesn't cause any side
> effects as far as I can tell (its been working this lockless
> way for years, mmap_sem is taken later in the loader code).
> Though for consistency sake we probably should set it up
> under the spinlock.

Ok, so elf loader doesn't change these parameters. Thanks for the explanation.