All of lore.kernel.org
 help / color / mirror / Atom feed
From: Yong Zhang <yong.zhang0@gmail.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kernel@vger.kernel.org, sergey.senozhatsky@gmail.com,
	bp@alien8.de, Ingo Molnar <mingo@elte.hu>,
	Tejun Heo <tj@kernel.org>, David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 1/4] lockdep: lock_set_subclass() fix
Date: Mon, 7 Nov 2011 21:31:31 +0800	[thread overview]
Message-ID: <20111107133131.GB2783@zhy> (raw)
In-Reply-To: <1320669279.18053.29.camel@twins>

On Mon, Nov 07, 2011 at 01:34:39PM +0100, Peter Zijlstra wrote:
> On Fri, 2011-11-04 at 17:26 +0800, Yong Zhang wrote:
> > Since commit f59de89 [lockdep: Clear whole lockdep_map on initialization],
> > lockdep_init_map() will clear all the struct. But it will break
> > lock_set_class()/lock_set_subclass(). A typical race condition
> > is like below:
> 
> This is a horridly ugly patch, why not simply revert that memset commit?

I prefer reverting that commit, but bugzilla is down and I don't know
what the real problem behind that commit.

> I really can't see the point of that, and keeping the name/key pointers
> around (which can only be over-written with the same values, right?)
> would also cure the problem.
> 
> Sadly the changelog is completely devoid of useful information (which is
> my own damn fault, I should never have accepted the patch in that form),
> so I can't actually comment on what it was supposed to fix.

me too :(
And going through lkml history, I find nothing about it.

> 
> Arguably kmemcheck is on crack or so since both name and key pointers
> should be in .data so there cannot be a leak by copying the thing over.

Maybe Tejun can give more detail on it.

Thanks,
Yong

  reply	other threads:[~2011-11-07 13:32 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-04  9:26 [PATCH 0/4] patches to cure race in lock_set_class() Yong Zhang
2011-11-04  9:26 ` [PATCH 1/4] lockdep: lock_set_subclass() fix Yong Zhang
2011-11-07 12:34   ` Peter Zijlstra
2011-11-07 13:31     ` Yong Zhang [this message]
2011-11-07 14:03       ` Tejun Heo
2011-11-07 13:54     ` Borislav Petkov
2011-11-07 15:28     ` Vegard Nossum
2011-11-07 16:10       ` Peter Zijlstra
2011-11-07 16:21         ` Tejun Heo
2011-11-07 16:26           ` Peter Zijlstra
2011-11-08  2:58         ` Yong Zhang
2011-11-08  3:02           ` Yong Zhang
2011-11-08  7:56           ` Peter Zijlstra
2011-11-08  8:14             ` Yong Zhang
2011-11-08  8:46               ` Peter Zijlstra
2011-11-08  9:07                 ` Yong Zhang
2011-11-08  9:37                   ` Yong Zhang
2011-11-08  9:40                   ` Peter Zijlstra
2011-11-09  8:04                     ` [PATCH 1/2] lockdep: kmemcheck: annotate ->lock in lockdep_init_map() Yong Zhang
2011-11-09  8:07                       ` [PATCH 2/2] lockdep: always try to set ->class_cache in register_lock_class() lockdep_init_map() Yong Zhang
2011-11-18 23:39                         ` [tip:core/locking] lockdep: Always " tip-bot for Yong Zhang
2011-12-06  9:39                       ` [tip:core/locking] lockdep, kmemcheck: Annotate ->lock in lockdep_init_map() tip-bot for Yong Zhang
2011-12-06 19:56                         ` David Rientjes
2011-12-06 20:14                       ` [tip:perf/urgent] " tip-bot for Yong Zhang
2011-11-08  2:22       ` [PATCH 1/4] lockdep: lock_set_subclass() fix Yong Zhang
2011-11-04  9:26 ` [RFC PATCH 2/4] lockdep: Let register_lock_class() can be called with/without graph_lock Yong Zhang
2011-11-04  9:26 ` [RFC PATCH 3/4] lockdep: split lockdep_init_map() Yong Zhang
2011-11-04  9:26 ` [RFC PATCH 4/4] lockdep: fix race condition in __lock_set_class() Yong Zhang
2011-11-07 12:30   ` Peter Zijlstra
2011-11-07 13:26     ` Yong Zhang
2011-11-06 11:52 ` [PATCH 0/4] patches to cure race in lock_set_class() Borislav Petkov

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=20111107133131.GB2783@zhy \
    --to=yong.zhang0@gmail.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=bp@alien8.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=rientjes@google.com \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=tj@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.