linux-kernel - Re: [PATCH] hrtimer: prevent migration for raising softirq

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]

Date:	Thu, 3 Jul 2008 19:03:06 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	torvalds@...ux-foundation.org, akpm@...uxfoundation.org,
	peterz@...radead.org, stable@...nel.org
Subject: Re: [PATCH] hrtimer: prevent migration for raising softirq

On Thu, 3 Jul 2008 21:56:00 -0400 (EDT) Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> 
> On Thu, 3 Jul 2008, Andrew Morton wrote:
> 
> >
> > On Thu, 3 Jul 2008 14:31:26 -0400 (EDT)
> > Steven Rostedt <rostedt@...dmis.org> wrote:
> >
> > > Due to a possible deadlock, the waking of the softirq was pushed outside
> > > of the hrtimer base locks. See commit 0c96c5979a522c3323c30a078a70120e29b5bdbc
> >
> > Please quote at least the patch title rather than raw hashes.
> 
> Sorry, will do next time. I'm getting to use to git.
> 
> >
> > afaict that patch isn't in 2.6.25 yet you copied stable@...nel.org.
> > Please clarify.
> 
> The reason I did so is because that commit has a Cc: stable@...nel.org.
> I figured that if that patch is in queue for stable this one should be in
> right afterwards.
> 
> >
> > >
> > > Unfortunately this allows the task to migrate after setting up the softirq
> > > and raising it. Since softirqs run a queue that is per-cpu we may raise the
> > > softirq on the wrong CPU and this will keep the queued softirq task from
> > > running.
> > >
> > > To solve this issue, this patch disables preemption around the releasing
> > > of the hrtimer lock and raising of the softirq.
> > >
> >
> > This seems to be 2.6.26 material and is inapplicable to 2.6.25?
> >
> 
> [/me goes to look at the 2.6.25.4 he has sitting around]
> 
> The above mentioned commit (Title: hrtimer: raise softirq unlocked to
> avoid circular lock dependency) is, in fact, in 2.6.25.4.
> 

Ah, OK, I'm a dope.
--
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/