Re: [PATCH tip/core/rcu 01/13] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU
From: Vlastimil Babka
Date: Thu Apr 13 2017 - 07:07:11 EST
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.
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