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")
>
One strange thing though: both of those 2 patches have been merged
during the 3.12 merge window. However the fix has been submitted to 3.10
and 3.11 stable kernels.
Thanks.
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