linux-kernel - Re: [PATCH] hung_task: Increment the global counter immediately

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Message-Id: <20260204100549.48436218179994b0303c8f49@linux-foundation.org>
Date: Wed, 4 Feb 2026 10:05:49 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Petr Mladek <pmladek@...e.com>
Cc: Lance Yang <lance.yang@...ux.dev>, Aaron Tomlin <atomlin@...mlin.com>,
 neelx@...e.com, sean@...e.io, mproche@...il.com, chjohnst@...il.com,
 nick.lange@...il.com, linux-kernel@...r.kernel.org, mhiramat@...nel.org,
 joel.granados@...nel.org, gregkh@...uxfoundation.org
Subject: Re: [PATCH] hung_task: Increment the global counter immediately

On Wed, 4 Feb 2026 12:04:54 +0100 Petr Mladek <pmladek@...e.com> wrote:

> A recent change allowed to reset the global counter of hung tasks using
> the sysctl interface. A potential race with the regular check has been
> solved by updating the global counter only once at the end of the check.
> 
> However, the hung task check can take a significant amount of time,
> particularly when task information is being dumped to slow serial
> consoles. Some users monitor this global counter to trigger immediate
> migration of critical containers. Delaying the increment until the
> full check completes postpones these high-priority rescue operations.
> 
> Update the global counter as soon as a hung task is detected. Since
> the value is read asynchronously, a relaxed atomic operation is
> sufficient.
> 
> Reported-by: Lance Yang <lance.yang@...ux.dev>
> Closes: https://lore.kernel.org/r/f239e00f-4282-408d-b172-0f9885f4b01b@linux.dev
> Signed-off-by: Petr Mladek <pmladek@...e.com>
> ---
> This is a followup patch for
> https://lore.kernel.org/r/20260125135848.3356585-1-atomlin@atomlin.com
> 
> Note that I could not use commit IDs because the original
> patchset is not in a stable tree yet. In fact, it seems
> that it is not even in linux-next at the moment.

Yes, I've gone into "fixes and trivial stuff only" mode, as we're at -rc8.

Aaron, please incorporate Petr's fix into v8 and resend towards the end
of the merge window?

Thanks.