From: Ingo Molnar <mingo@elte.hu>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
adobriyan@gmail.com, Doug Chapman <doug.chapman@hp.com>,
Peter Zijlstra <peterz@infradead.org>,
Roland McGrath <roland@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] account_group_exec_runtime: fix the racy usage of ->signal
Date: Sat, 8 Nov 2008 10:28:02 +0100 [thread overview]
Message-ID: <20081108092802.GA32664@elte.hu> (raw)
In-Reply-To: <20081107174016.GA24812@redhat.com>
* Oleg Nesterov <oleg@redhat.com> wrote:
> On 11/07, Ingo Molnar wrote:
> >
> > * Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > > --- K-28/kernel/sched_stats.h~A_G_E_R_FIX 2008-11-07 17:32:02.000000000 +0100
> > > +++ K-28/kernel/sched_stats.h 2008-11-07 17:44:39.000000000 +0100
> > > @@ -351,10 +351,12 @@ static inline void account_group_exec_ru
> > > unsigned long long ns)
> > > {
> > > struct signal_struct *sig;
> > > + unsigned long flags;
> > >
> > > - sig = tsk->signal;
> > > - if (unlikely(!sig))
> > > + if (unlikely(!lock_task_sighand(tsk, &flags)))
> > > return;
> >
> > i think this will lock up:
>
> Ah. I worried about this, but convinced myself this is OK...
>
> > the signal lock must not nest inside the rq
> > lock, and these accounting functions are called from within the
> > scheduler.
>
> Why? we seem to never do task_rq_lock() under ->siglock ?
signal_wake_up() ?
Ingo
next prev parent reply other threads:[~2008-11-08 9:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-07 16:52 [PATCH] account_group_exec_runtime: fix the racy usage of ->signal Oleg Nesterov
2008-11-07 16:21 ` Ingo Molnar
2008-11-07 16:58 ` Doug Chapman
2008-11-07 18:42 ` Oleg Nesterov
2008-11-07 17:40 ` Oleg Nesterov
2008-11-08 9:28 ` Ingo Molnar [this message]
2008-11-10 13:04 ` Oleg Nesterov
2008-11-10 12:13 ` Peter Zijlstra
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=20081108092802.GA32664@elte.hu \
--to=mingo@elte.hu \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=doug.chapman@hp.com \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=roland@redhat.com \
/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