linux-kernel - Re: [PATCH tip/core/rcu 01/13] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY

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]

Message-Id: <20170413172438.GA10199@linux.vnet.ibm.com>
Date:   Thu, 13 Apr 2017 10:24:38 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, rostedt@...dmis.org,
        dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
        oleg@...hat.com, bobby.prani@...il.com,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org
Subject: Re: [PATCH tip/core/rcu 01/13] mm: Rename SLAB_DESTROY_BY_RCU to
 SLAB_TYPESAFE_BY_RCU

On Thu, Apr 13, 2017 at 06:17:09PM +0200, Peter Zijlstra wrote:
> On Thu, Apr 13, 2017 at 01:06:56PM +0200, Vlastimil Babka wrote:
> > On 04/13/2017 11:12 AM, Peter Zijlstra wrote:
> > > On Wed, Apr 12, 2017 at 09:55:37AM -0700, Paul E. McKenney wrote:
> > >> A group of Linux kernel hackers reported chasing a bug that resulted
> > >> from their assumption that SLAB_DESTROY_BY_RCU provided an existence
> > >> guarantee, that is, that no block from such a slab would be reallocated
> > >> during an RCU read-side critical section.  Of course, that is not the
> > >> case.  Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire
> > >> slab of blocks.
> > > 
> > > And that while we wrote a huge honking comment right along with it...
> > > 
> > >> [ paulmck: Add "tombstone" comments as requested by Eric Dumazet. ]
> > > 
> > > I cannot find any occurrence of "tomb" or "TOMB" in the actual patch,
> > > confused?
> > 
> > It's the comments such as:
> > 
> > + * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.
> > 
> > so that people who remember the old name can git grep its fate.
> 
> git log -S SLAB_DESTROY_BY_RCU

My (perhaps naive) hope is that having more than one path to
the information will reduce the number of "Whatever happened to
SLAB_DESTROY_BY_RCU?" queries.

							Thanx, Paul