[PATCH v2 0/2] workqueue: Fix rescuer task's name truncated

[PATCH v2 0/2] workqueue: Fix rescuer task's name truncated

[Wenchao Hao]

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().

The first patch fix the rescuer task's name truncated;
The second patch fix workqueue_struct's name truncated.

V2:
Add another patch to increased worker desc's length to 32 to fix compile
warning reported:
https://lore.kernel.org/oe-kbuild-all/202405131400.sEYZHYk2-lkp@intel.com/

Wenchao Hao (2):
  workqueue: Fix rescuer task's name truncated
  workqueue: Increase worker desc's length to 32

 include/linux/workqueue.h | 2 +-
 kernel/workqueue.c        | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

-- 
2.32.0

[PATCH v2 1/2] workqueue: Fix rescuer task's name truncated

[Wenchao Hao]

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_]

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@huawei.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
---
 kernel/workqueue.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d2dbe099286b..07c077a53f93 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5443,7 +5443,7 @@ 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",
@@ -5452,6 +5452,8 @@ 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);
@@ -6302,6 +6304,8 @@ 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);
 		}
 	}
 
-- 
2.32.0

[PATCH v2 2/2] workqueue: Increase worker desc's length to 32

[Wenchao Hao]

Commit 31c89007285d ("workqueue.c: Increase workqueue name length")
increased WQ_NAME_LEN from 24 to 32, but forget to increase
WORKER_DESC_LEN, which would cause truncation when setting kworker's
desc from workqueue_struct's name, such as usage in process_one_work().

Fixes: 31c89007285d ("workqueue.c: Increase workqueue name length")

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202405131400.sEYZHYk2-lkp@intel.com/
Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
---
 include/linux/workqueue.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 158784dd189a..72031fa80414 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -92,7 +92,7 @@ enum wq_misc_consts {
 	WORK_BUSY_RUNNING	= 1 << 1,
 
 	/* maximum string length for set_worker_desc() */
-	WORKER_DESC_LEN		= 24,
+	WORKER_DESC_LEN		= 32,
 };
 
 /* Convenience constants - of type 'unsigned long', not 'enum'! */
-- 
2.32.0

Re: [PATCH v2 0/2] workqueue: Fix rescuer task's name truncated

[Wenchao Hao]

On 2024/5/13 22:01, 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().
> 
> The first patch fix the rescuer task's name truncated;
> The second patch fix workqueue_struct's name truncated.
> 

Friendly ping...

> V2:
> Add another patch to increased worker desc's length to 32 to fix compile
> warning reported:
> https://lore.kernel.org/oe-kbuild-all/202405131400.sEYZHYk2-lkp@intel.com/
> 
> Wenchao Hao (2):
>    workqueue: Fix rescuer task's name truncated
>    workqueue: Increase worker desc's length to 32
> 
>   include/linux/workqueue.h | 2 +-
>   kernel/workqueue.c        | 6 +++++-
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 

Re: [PATCH v2 0/2] workqueue: Fix rescuer task's name truncated

[Tejun Heo]

Hello,

On Thu, May 23, 2024 at 09:36:57AM +0800, Wenchao Hao wrote:
> > The first patch fix the rescuer task's name truncated;
> > The second patch fix workqueue_struct's name truncated.

I missed these and the issue got reported separately and a different fix has
been applied:

  https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git/commit/?h=for-6.10-fixes&id=2a1b02bcba78f8498ab00d6142e1238d85b01591

My apologies for missing your patches. Can you please see whether the above
patch addresses the issues you saw.

Thanks.

-- 
tejun

Re: [PATCH v2 0/2] workqueue: Fix rescuer task's name truncated

[Wenchao Hao]

On 2024/5/27 2:50, Tejun Heo wrote:
> Hello,
> 
> On Thu, May 23, 2024 at 09:36:57AM +0800, Wenchao Hao wrote:
>>> The first patch fix the rescuer task's name truncated;
>>> The second patch fix workqueue_struct's name truncated.
> 
> I missed these and the issue got reported separately and a different fix has
> been applied:
> 
>    https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git/commit/?h=for-6.10-fixes&id=2a1b02bcba78f8498ab00d6142e1238d85b01591
> 

I applied these changes and the issue has been fixed.

> My apologies for missing your patches. Can you please see whether the above
> patch addresses the issues you saw.
>  > Thanks.
>