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Message-ID: <00b43845-c990-481f-be0a-4bf15ada8b3c@huawei.com>
Date: Tue, 23 Apr 2024 12:55:22 +0800
From: Wenchao Hao <haowenchao2@...wei.com>
To: Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>, Aaron
Tomlin <atomlin@...mlin.com>, <linux-kernel@...r.kernel.org>
CC: Wenchao Hao <haowenchao22@...il.com>
Subject: Re: [RFC PATCH] workqueue: Fix rescuer task's name truncated
On 2024/4/24 2:21, Wenchao Hao wrote:
> Task comm of task is limitted to 16, prefix "kworker/R-" is added for
> rescuer worker's task, which cause most task name is truncated as
> following:
>
> root 81 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-xprti]
> root 82 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-cfg80]
> root 85 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-nfsio]
> root 86 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-xfsal]
> root 87 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-xfs_m]
> root 88 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-acpi_]
> root 93 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-iscsi]
> root 95 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-scsi_]
> root 97 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-scsi_]
> root 99 0.0 0.0 0 0 ? I< 11:18 0:00 [kworker/R-scsi_]
>
> I want to fix this issue by split rescuer name to 2 part like other
> kworker, the normal part is "kworker/R" which is set to task_struct's comm,
> another part is wq->name which is added to kworker's desc. These 2 parts
> would be merged in wq_worker_comm().
>
> Fixes: b6a46f7263bd ("workqueue: Rename rescuer kworker")
>
> Signed-off-by: Wenchao Hao <haowenchao2@...wei.com>
> ---
> kernel/workqueue.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 0066c8f6c154..0ce9e8597a4d 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -5430,7 +5430,7 @@ static int init_rescuer(struct workqueue_struct *wq)
> }
>
> rescuer->rescue_wq = wq;
> - rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R-%s", wq->name);
> + rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R");
> if (IS_ERR(rescuer->task)) {
> ret = PTR_ERR(rescuer->task);
> pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",
> @@ -5439,6 +5439,8 @@ static int init_rescuer(struct workqueue_struct *wq)
> return ret;
> }
>
> + snprintf(rescuer->desc, sizeof(rescuer->desc), "%s", wq->name);
> +
> wq->rescuer = rescuer;
> if (wq->flags & WQ_UNBOUND)
> kthread_bind_mask(rescuer->task, wq_unbound_cpumask);
> @@ -6289,6 +6291,8 @@ void wq_worker_comm(char *buf, size_t size, struct task_struct *task)
> worker->desc);
> }
> raw_spin_unlock_irq(&pool->lock);
> + } else if (worker->desc[0] != '\0') {
> + scnprintf(buf + off, size - off, "-%s", worker->desc);
> }
Hi Tejun and all:
I added another logic in wq_worker_comm() to append worker's desc when
worker is not attached to a work pool. I don't know why the origin
logic only append worker's desc when worker is attached to a work pool,
so I am not sure if it's safe to using worker here directly.
> }
>
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