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").
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