linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
To: David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Linus Torvalds
	<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>,
	KAMEZAWA Hiroyuki
	<kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [patch for-3.12] mm, memcg: protect mem_cgroup_read_events for cpu hotplug
Date: Tue, 1 Oct 2013 22:22:27 -0400	[thread overview]
Message-ID: <20131002022227.GR856@cmpxchg.org> (raw)
In-Reply-To: <alpine.DEB.2.02.1310011629350.27758-X6Q0R45D7oAcqpCFd4KODRPsWskHk0ljAL8bYrjMMd8@public.gmane.org>

On Tue, Oct 01, 2013 at 04:31:23PM -0700, David Rientjes wrote:
> for_each_online_cpu() needs the protection of {get,put}_online_cpus() so
> cpu_online_mask doesn't change during the iteration.

There is no problem report here.

Is there a crash?

If it's just accuracy of the read, why would we care about some
inaccuracies in counters that can change before you even get the
results to userspace?  And care to the point where we hold up CPU
hotplugging for this?

Also, the fact that you directly sent this to Linus suggests there is
some urgency for this fix.  What's going on?

Thanks,
Johannes

  parent reply	other threads:[~2013-10-02  2:22 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-01 23:31 David Rientjes
2013-10-02  0:47 ` KOSAKI Motohiro
     [not found] ` <alpine.DEB.2.02.1310011629350.27758-X6Q0R45D7oAcqpCFd4KODRPsWskHk0ljAL8bYrjMMd8@public.gmane.org>
2013-10-02  2:22   ` Johannes Weiner [this message]
2013-10-02  3:08     ` David Rientjes

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=20131002022227.GR856@cmpxchg.org \
    --to=hannes-druugvl0lcnafugrpc6u6w@public.gmane.org \
    --cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
    --cc=cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org \
    --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org \
    --cc=mhocko-AlSwsSmVLrQ@public.gmane.org \
    --cc=rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org \
    --cc=torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.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