From: Cyrill Gorcunov <gorcunov@gmail.com>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>,
brgl@bgdev.pl, arunks@codeaurora.org, geert+renesas@glider.be,
mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org,
ldufour@linux.ibm.com, rppt@linux.ibm.com, mguzik@redhat.com,
mkoutny@suse.cz, vbabka@suse.cz, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] mm: get_cmdline use arg_lock instead of mmap_sem
Date: Tue, 30 Apr 2019 16:24:03 +0300 [thread overview]
Message-ID: <20190430132403.GG2673@uranus.lan> (raw)
In-Reply-To: <20190430105609.GA23779@blackbody.suse.cz>
On Tue, Apr 30, 2019 at 12:56:10PM +0200, Michal Koutný wrote:
> On Tue, Apr 30, 2019 at 01:45:17PM +0300, Cyrill Gorcunov <gorcunov@gmail.com> wrote:
> > It setups these parameters unconditionally. I need to revisit
> > this moment. Technically (if only I'm not missing something
> > obvious) we might have a race here with prctl setting up new
> > params, but this should be harmless since most of them (except
> > stack setup) are purely informative data.
>
> FTR, when I reviewed that usage, I noticed it was missing the
> synchronization. My understanding was that the mm_struct isn't yet
> shared at this moment. I can see some of the operations take place after
> flush_old_exec (where current->mm = mm_struct), so potentially it is
> shared since then. OTOH, I guess there aren't concurrent parties that
> could access the field at this stage of exec.
Just revisited this code -- we're either executing prctl, either execve.
Since both operates with current task we're safe.
next prev parent reply other threads:[~2019-04-30 13:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 12:03 [PATCH] mm: get_cmdline use arg_lock instead of mmap_sem Michal Koutný
2019-04-17 13:41 ` Michal Hocko
2019-04-17 14:41 ` Michal Koutný
2019-04-17 14:55 ` Michal Hocko
2019-04-18 13:50 ` [PATCH] prctl_set_mm: downgrade mmap_sem to read lock Michal Koutný
2019-04-18 14:09 ` Cyrill Gorcunov
2019-04-18 14:15 ` Michal Hocko
2019-04-18 14:27 ` Laurent Dufour
2019-04-18 18:23 ` Cyrill Gorcunov
2019-04-30 8:18 ` [PATCH 0/3] Reduce mmap_sem usage for args manipulation Michal Koutný
2019-04-30 8:18 ` [PATCH 1/3] mm: get_cmdline use arg_lock instead of mmap_sem Michal Koutný
2019-04-30 9:09 ` Kirill Tkhai
2019-04-30 9:38 ` Cyrill Gorcunov
2019-04-30 9:53 ` Kirill Tkhai
2019-04-30 10:45 ` Cyrill Gorcunov
2019-04-30 10:56 ` Michal Koutný
2019-04-30 13:24 ` Cyrill Gorcunov [this message]
2019-04-30 8:18 ` [PATCH 2/3] prctl_set_mm: Refactor checks from validate_prctl_map Michal Koutný
2019-04-30 9:27 ` Kirill Tkhai
2019-04-30 8:18 ` [PATCH 3/3] prctl_set_mm: downgrade mmap_sem to read lock Michal Koutný
2019-04-30 8:55 ` Kirill Tkhai
2019-04-30 9:08 ` Cyrill Gorcunov
2019-04-30 9:11 ` Kirill Tkhai
2019-05-02 12:52 ` [PATCH v3 0/2] Reduce mmap_sem usage for args manipulation Michal Koutný
2019-05-02 12:52 ` [PATCH v3 1/2] prctl_set_mm: Refactor checks from validate_prctl_map Michal Koutný
2019-05-02 20:57 ` Cyrill Gorcunov
2019-05-02 12:52 ` [PATCH v3 2/2] prctl_set_mm: downgrade mmap_sem to read lock Michal Koutný
2019-05-02 20:57 ` Cyrill Gorcunov
2019-05-06 9:28 ` Kirill Tkhai
2019-05-07 17:42 ` Michal Hocko
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