linux-kernel - Re: [PATCH V3] writeback: Fix wakeup and logging timeouts for !DETECT_HUNG

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Message-ID: <btfdnzqktucegolmalsawd3oj4htzl4mafybgyx6zqqlwpe3q5@lu4ntvit6zhf>
Date: Tue, 3 Feb 2026 15:02:46 +0100
From: "Pankaj Raghav (Samsung)" <pankaj.raghav@...ux.dev>
To: Huacai Chen <chenhuacai@...ngson.cn>
Cc: Huacai Chen <chenhuacai@...nel.org>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	linux-fsdevel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>, 
	Julian Sun <sunjunchao@...edance.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] writeback: Fix wakeup and logging timeouts for
 !DETECT_HUNG_TASK

On Tue, Feb 03, 2026 at 05:40:14PM +0800, Huacai Chen wrote:
> Recent changes of fs-writeback cause such warnings if DETECT_HUNG_TASK
> is not enabled:
> 
> INFO: The task sync:1342 has been waiting for writeback completion for more than 1 seconds.
> 
> The reason is sysctl_hung_task_timeout_secs is 0 when DETECT_HUNG_TASK
> is not enabled, then it causes the warning message even if the writeback
> lasts for only one second.
> 
> Guard the wakeup and logging with "#ifdef CONFIG_DETECT_HUNG_TASK" can
> eliminate the warning messages. But on the other hand, it is possible
> that sysctl_hung_task_timeout_secs be also 0 when DETECT_HUNG_TASK is
> enabled. So let's just check the value of sysctl_hung_task_timeout_secs
> to decide whether do wakeup and logging.
> 
> Fixes: 1888635532fb ("writeback: Wake up waiting tasks when finishing the writeback of a chunk.")
> Fixes: d6e621590764 ("writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)")
> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> ---
> V2: Disable wakeup and logging for !DETECT_HUNG_TASK.
> V3: Also handle the case for DETECT_HUNG_TASK if sysctl_hung_task_timeout_secs is 0.

Looks good,
Reviewed-by: Pankaj Raghav <p.raghav@...sung.com>
-- 
Pankaj