From: Yang Shi <yang.shi@linux.alibaba.com>
To: Cyrill Gorcunov <gorcunov@gmail.com>, Michal Hocko <mhocko@kernel.org>
Cc: adobriyan@gmail.com, willy@infradead.org, mguzik@redhat.com,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [v3 PATCH] mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct
Date: Tue, 10 Apr 2018 09:21:19 -0700 [thread overview]
Message-ID: <097488c7-ab18-367b-c435-7c26d149c619@linux.alibaba.com> (raw)
In-Reply-To: <20180410122804.GD2041@uranus.lan>
On 4/10/18 5:28 AM, Cyrill Gorcunov wrote:
> On Tue, Apr 10, 2018 at 01:10:01PM +0200, Michal Hocko wrote:
>>> Because do_brk does vma manipulations, for this reason it's
>>> running under down_write_killable(&mm->mmap_sem). Or you
>>> mean something else?
>> Yes, all we need the new lock for is to get a consistent view on brk
>> values. I am simply asking whether there is something fundamentally
>> wrong by doing the update inside the new lock while keeping the original
>> mmap_sem locking in the brk path. That would allow us to drop the
>> mmap_sem lock in the proc path when looking at brk values.
> Michal gimme some time. I guess we might do so, but I need some
> spare time to take more precise look into the code, hopefully today
> evening. Also I've a suspicion that we've wracked check_data_rlimit
> with this new lock in prctl. Need to verify it again.
I see you guys points. We might be able to move the drop of mmap_sem
before setting mm->brk in sys_brk since mmap_sem should be used to
protect vma manipulation only, then protect the value modify with the
new arg_lock. Then we can eliminate mmap_sem stuff in prctl path, and it
also prevents from wrecking check_data_rlimit.
At the first glance, it looks feasible to me. Will look into deeper later.
Thanks,
Yang
next prev parent reply other threads:[~2018-04-10 16:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-09 21:52 [v3 PATCH] mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct Yang Shi
2018-04-10 8:48 ` Cyrill Gorcunov
2018-04-10 9:09 ` Michal Hocko
2018-04-10 9:40 ` Cyrill Gorcunov
2018-04-10 10:42 ` Michal Hocko
2018-04-10 11:02 ` Cyrill Gorcunov
2018-04-10 11:10 ` Michal Hocko
2018-04-10 12:28 ` Cyrill Gorcunov
2018-04-10 16:21 ` Yang Shi [this message]
2018-04-10 18:28 ` Yang Shi
2018-04-10 18:28 ` Yang Shi
2018-04-10 19:17 ` Cyrill Gorcunov
2018-04-10 19:17 ` Cyrill Gorcunov
2018-04-10 19:33 ` Yang Shi
2018-04-10 19:33 ` Yang Shi
2018-04-10 20:06 ` Cyrill Gorcunov
2018-04-12 12:18 ` Michal Hocko
2018-04-12 12:18 ` Michal Hocko
2018-04-12 16:20 ` Yang Shi
2018-04-12 16:20 ` Yang Shi
2018-04-13 6:56 ` Michal Hocko
2018-04-13 6:56 ` Michal Hocko
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