linux-kernel - Re: [Patch v4 1/2] freezer: check OOM kill while being frozen

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAM_iQpXiJL=q6NFkiPF71dZHKXu=ReJ59Rbadc__+UX-GW2x8A@mail.gmail.com>
Date:	Mon, 8 Sep 2014 16:16:15 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Tejun Heo <tj@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	David Rientjes <rientjes@...gle.com>,
	Michal Hocko <mhocko@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [Patch v4 1/2] freezer: check OOM kill while being frozen

On Mon, Sep 8, 2014 at 4:23 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>
> The reason why it matters for the suspend-time freezing is that we freeze tasks
> to take them out of the picture entirely until they are thawed.  Therefore we
> can't allow them to go back to the picture just for a while until they are
> killed.  Frozen tasks are not supposed to get back to the picture at all.
>

Ok, then checking TIF_MEMDIE is unsafe for PM freeze, we should
keep the cgroup_freezing() test to make sure freeze request is from
cgroup not PM. Question got answered. :)

I will put the following as a comment:

/* OOM killer may decide to kill this process after it is frozen,
   in this case SIGKILL can never be handled, so we should check
  TIF_MEMDIE and if it is set, thaw and let SIGKILL kill it.
  But for PM freeze, it is not allowed to get out even for a while,
  so we have to keep it being frozen. */

Let me know if it looks good to you.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/