From: Mateusz Guzik <mguzik@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>,
adobriyan@gmail.com, willy@infradead.org, gorcunov@openvz.org,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH] mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct
Date: Tue, 27 Mar 2018 16:31:23 +0200 [thread overview]
Message-ID: <20180327143122.rjgxjoj2adzvfck2@mguzik> (raw)
In-Reply-To: <20180327062939.GV5652@dhcp22.suse.cz>
On Tue, Mar 27, 2018 at 08:29:39AM +0200, Michal Hocko wrote:
> On Tue 27-03-18 02:20:39, Yang Shi wrote:
> [...]
> The patch looks reasonable to me. Maybe it would be better to be more
> explicit about the purpose of the patch. As others noticed, this alone
> wouldn't solve the mmap_sem contention issues. I _think_ that if you
> were more explicit about the mmap_sem abuse it would trigger less
> questions.
>
>From what I gather even with other fixes the kernel will still end up
grabbing the semaphore. In this case I don't see what's the upside of
adding the spinlock for args. The downside is growth of mm_struct.
i.e. the code can be refactored to just hold the lock and relock only if
necessary (unable to copy to user without faulting)
--
Mateusz Guzik
next prev parent reply other threads:[~2018-03-27 14:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 18:20 Yang Shi
2018-03-26 18:37 ` Matthew Wilcox
2018-03-26 19:21 ` Cyrill Gorcunov
2018-03-26 21:10 ` Tetsuo Handa
2018-03-26 21:20 ` Yang Shi
2018-03-26 21:29 ` Cyrill Gorcunov
2018-03-26 22:00 ` Tetsuo Handa
2018-03-26 22:12 ` Yang Shi
2018-03-27 7:38 ` Cyrill Gorcunov
2018-03-27 7:37 ` Cyrill Gorcunov
2018-03-26 21:59 ` Yang Shi
2018-03-27 7:32 ` Cyrill Gorcunov
2018-03-27 18:44 ` Yang Shi
2018-03-26 19:42 ` Mateusz Guzik
2018-03-26 21:10 ` Yang Shi
2018-03-27 6:29 ` Michal Hocko
2018-03-27 14:31 ` Mateusz Guzik [this message]
2018-03-27 14:43 ` Michal Hocko
2018-03-27 18:38 ` Yang Shi
2018-03-27 18:52 ` Cyrill Gorcunov
2018-03-28 13:10 ` Michal Hocko
2018-04-02 1:58 ` Yang Shi
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