Re: Is "fix shm_file deletion races" patch required by 3.4.x ?

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On 12/11/2013 10:52 PM, Greg Thelen wrote:
> On Wed, Dec 11 2013, Francis Moreau wrote:
> 
>> On 12/11/2013 06:54 PM, Greg Thelen wrote:
>> [...]
>>>
>>> I don't think that 3.4 suffers the same problem.  So I don't see any
>>> reason to apply "fix shm_file deletion races" to 3.4.x.  3.4 is immune
>>> because it use exclusive locking (spinlock) for shm-id-to-shm-object
>>> conversions (shm_lock_check() in shmctl()).  Newer kernels use rcu
>>> protected schemes so more races are possible.  Furthermore, I ran some
>>> quick tests on v3.4.71 and did not find any crashes.  So I don't think
>>> 3.4.x needs this patch.
>>>
>>
>> Ah ok, thank you for your insight.
>>
>> Maybe also adding a reference to the commit that introduced the bug
>> would help but that would add extra work.
>>
>> Thanks
> 
> From patch a399b29dfbaa ("ipc,shm: fix shm_file deletion races") commit
> log:
>     Fixes: c2c737a0461e ("ipc,shm: shorten critical region for shmat")
>     Fixes: 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl")
> 
> I think that these two patches are the ones to look for.  Any kernels
> which contain either c2c737a0461e or 2caacaa82a51 are likely to need
> a399b29dfbaa ("ipc,shm: fix shm_file deletion races").
> 

Thanks !

For some reasons I didn't see them.
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