linux-kernel - Re: [PATCH] kernel/hung_task.c: export sysctl_hung_task_timeout

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Message-ID: <Zc2giqMeZhxuDSU9@infradead.org>
Date: Wed, 14 Feb 2024 21:26:34 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	fuyuanli <fuyuanli@...iglobal.com>
Subject: Re: [PATCH] kernel/hung_task.c: export sysctl_hung_task_timeout_secs

On Fri, Feb 09, 2024 at 02:09:35AM -0500, Kent Overstreet wrote:
> needed for thread_with_file; also rare but not unheard of to need this
> in module code, when blocking on user input.
> 
> one workaround used by some code is wait_event_interruptible() - but
> that can be buggy if the outer context isn't expecting unwinding.

I don't think just exporting the variable ad thus allowing write
access is a good idea.  If we want to keep going down the route of
this hack we should add an accessor function that returns the value.

The cleaner solution would be a new task state that explicitly
marks code than can sleep forever without triggerring the hang
check.  Although this might be a bit invaѕive and take a while.