Messages in this thread | | | Subject | Re: mm: deadlock between get_online_cpus/pcpu_alloc | From | Vlastimil Babka <> | Date | Tue, 7 Feb 2017 10:49:28 +0100 |
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On 02/07/2017 10:43 AM, Mel Gorman wrote: > If I'm reading this right, a hot-remove will set the pool POOL_DISASSOCIATED > and unbound. A workqueue queued for draining get migrated during hot-remove > and a drain operation will execute twice on a CPU -- one for what was > queued and a second time for the CPU it was migrated from. It should still > work with flush_work which doesn't appear to block forever if an item > got migrated to another workqueue. The actual drain workqueue function is > using the CPU ID it's currently running on so it shouldn't get confused.
Is the worker that will process this migrated workqueue also guaranteed to be pinned to a cpu for the whole work, though? drain_local_pages() needs that guarantee.
> Tejun, did I miss anything? Does a workqueue item queued on a CPU being > offline get unbound and a caller can still flush it safely? In this > specific case, it's ok that the workqueue item does not run on the CPU it > was queued on. >
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