linux-kernel - Re: [PATCH] USB: core: hub: fix usb_hub worker blocking drain_all

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Message-ID: <Y90egBL6HSoEdz2P@rowland.harvard.edu>
Date:   Fri, 3 Feb 2023 09:47:28 -0500
From:   Alan Stern <stern@...land.harvard.edu>
To:     Zhu Zhongjie <zhongjiezhu1@...il.com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] USB: core: hub: fix usb_hub worker blocking
 drain_all_pages() worker issue

On Fri, Feb 03, 2023 at 03:28:19PM +0800, Zhu Zhongjie wrote:
> From: Zhongjie Zhu <zhongjiezhu1@...il.com>
> 
> When disconnecting a usb mass storege, if there are a lot of inodes
> like 10 thousands files need to be freed, the invalidate_inodes() will
> run for a loog time to freeing all inodes, this will block other worker
> to run in the cpu, so mark the usb_hub workqueue to WQ_CPU_INTENSIVE to
> avoid this situation.

Very infrequently this will happen.  In the vast majority of cases, the 
usb_hub workqueue uses very little CPU time.  Marking it 
WQ_CPU_INTENSIVE seems inappropriate.

Alan Stern