Messages in this thread | | | Date | Tue, 6 Jun 2017 17:56:01 +0200 | From | Oleg Nesterov <> | Subject | Re: double call identical release when there is a race hitting |
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I can't answer authoritatively, but
On 06/06, zhong jiang wrote: > > Hi > > when I review the code, I find the following scenario will lead to a race , > but I am not sure whether the real issue will hit or not. > > cpu1 cpu2 > exit_mmap mmu_notifier_unregister > __mmu_notifier_release srcu_read_lock > srcu_read_lock > mm->ops->release(mn, mm) mm->ops->release(mn,mm) > srcu_read_unlock srcu_read_unlock > > > obviously, the specified mm will call identical release function when > the related condition satisfy. is it right?
I think you are right, this is possible, perhaps the comments should mention this explicitly.
See the changelog in d34883d4e35c0a994e91dd847a82b4c9e0c31d83 "mm: mmu_notifier: re-fix freed page still mapped in secondary MMU":
"multiple ->release() callouts", we needn't care it too much ...
Oleg.
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