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ca4aa97194
The normal task_work path used a tw_pending bit to ensure the callback was only added once: the mpscq drains incrementally, so a single tctx_task_work() run can take the queue through empty -> non-empty several times, and each transition would otherwise re-add the already pending callback_head. This corrupts the task_work list, and is what tw_pending protects again. This can go away, if we stop running the task_work as soon as the queue empties. Suggested-by: Caleb Sander Mateos <csander@purestorage.com> Reviewed-by: Caleb Sander Mateos <csander@purestorage.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>