Re: [PATCH block/for-3.3/core] block: an exiting task should be allowedto create io_context

From: Jens Axboe
Date: Sun Dec 25 2011 - 08:29:56 EST

On 2011-12-25 02:02, Tejun Heo wrote:
> While fixing io_context creation / task exit race condition,
> 6e736be7f2 "block: make ioc get/put interface more conventional and
> fix race on alloction" also prevented an exiting (%PF_EXITING) task
> from creating its own io_context. This is incorrect as exit path may
> issue IOs, e.g. from exit_files(), and if those IOs are the first ones
> issued by the task, io_context needs to be created to process the IOs.
> Combined with the existing problem of io_context / io_cq creation
> failure having the possibility of stalling IO, this problem results in
> deterministic full IO lockup with certain workloads.
> Fix it by allowing io_context creation regardless of %PF_EXITING for
> %current.

Thanks, applied.

Jens Axboe

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