From: Oleg Nesterov <oleg@redhat.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: security@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kthread: Make kthread_create() killable.
Date: Sun, 15 Sep 2013 18:39:19 +0200 [thread overview]
Message-ID: <20130915163919.GC13344@redhat.com> (raw)
In-Reply-To: <201309150846.HED51521.tJOFOMVFSOHQFL@I-love.SAKURA.ne.jp>
On 09/15, Tetsuo Handa wrote:
>
> Oleg Nesterov wrote:
> > I am wondering if this can be simplified...
> >
> > At least you can move create->done from kthread_create_info to the
> > stack, and turn create->owner into the pointer to that completion.
>
> Use of DECLARE_COMPLETION_ONSTACK() looks harmful to me because current thread
> needs to be able to terminate as soon as possible if SIGKILLed
Sure.
> If we move something from kmalloc()ed zone to stack,
> current thread cannot be terminated until that something is guaranteed to no
> longer be used.
Please look at call_usermodehelper_exec() which does this trick. The
logic is the same, just you need to xchg(create->completion) instead
of create->owner.
In any case "void *owner" looks strange. It is in fact boolean (in
your patch). You can even use, say, test_and_set_bit() instead of
xchg.
Oleg.
next prev parent reply other threads:[~2013-09-15 16:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <201309132318.HEC05218.OtVOFOFMLJHFQS@I-love.SAKURA.ne.jp>
2013-09-14 16:05 ` [PATCH] kthread: Make kthread_create() killable Oleg Nesterov
2013-09-14 23:46 ` Tetsuo Handa
2013-09-15 16:39 ` Oleg Nesterov [this message]
2013-09-16 0:53 ` [PATCH v2] " Tetsuo Handa
2013-09-23 23:07 ` Andrew Morton
2013-09-24 15:17 ` [PATCH v3] " Tetsuo Handa
2013-09-24 16:38 ` Oleg Nesterov
2013-09-25 21:05 ` David Rientjes
2013-09-26 2:59 ` Tetsuo Handa
2013-09-26 18:53 ` David Rientjes
2013-09-28 7:18 ` Tetsuo Handa
2013-09-30 21:57 ` David Rientjes
2013-10-01 13:20 ` Tetsuo Handa
2013-10-02 7:06 ` David Rientjes
2013-10-02 13:44 ` Tetsuo Handa
[not found] ` <201309152038.DDJ59271.OJMOHLFtSFOQVF@I-love.SAKURA.ne.jp>
2013-09-15 16:55 ` [PATCH] " Oleg Nesterov
2013-09-16 7:25 ` [PATCH] coredump: Make startup of coredump to pipe killable Tetsuo Handa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130915163919.GC13344@redhat.com \
--to=oleg@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=security@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).