Bug 1400252

Summary: Used greatest stack depth
Product: [Fedora] Fedora Reporter: Tomasz Kłoczko <kloczko.tomasz>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: rawhideCC: cz172638, gansalmon, ichavero, itamar, jonathan, kernel-maint, labbott, madhu.chinakonda, mchehab
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Hardware: All   
OS: Linux   
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Last Closed: 2016-11-30 18:34:26 UTC Type: Bug
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Description Tomasz Kłoczko 2016-11-30 18:02:40 UTC 
After upgrade to 4.9.0-0.rc6.git2.1.fc26 on x86_64 and armv7hl I'm finding many times in kernel logs lines like 

[66523.177407] dnf (2286) used greatest stack depth: 4092 bytes left
[88709.555128] dnf (2628) used greatest stack depth: 3908 bytes left
[96827.069910] kworker/dying (6) used greatest stack depth: 3156 bytes left

Also I have impression that general responsiveness desktop application is degraded.
Just back to 4.9.0-0.rc5.git4.1.fc26 and seems speed is now better however even this version time to  time as ell reports the same kernel issue.
Just found in logs on 4.9.0-0.rc5.git4.1.fc26:

[ 6964.284807] kworker/dying (633) used greatest stack depth: 9616 bytes left
Comment 1 Laura Abbott 2016-11-30 18:34:26 UTC 
That message is just informational. It does not indicate an problem with the kernel.
Comment 2 Tomasz Kłoczko 2016-11-30 20:27:27 UTC 
If it is not a bug why it is reported even as notification?
Comment 3 Laura Abbott 2016-11-30 20:46:19 UTC 
It's designed to track potential issues if a process is using a large amount of stack space.
Comment 4 Tomasz Kłoczko 2016-11-30 20:51:55 UTC 
So if such problem is reported in kworker/dying which is kernel thread it is something which should be reported as kernel bug. Isn't it?
Comment 5 Laura Abbott 2016-11-30 23:15:10 UTC 
No. It's not a problem. It's only reporting how much stack space is left. The feature that turns this on reports a message of the most amount of stack space used. The fact that a message is being reported does not mean the thread is in danger of running out of stack space, it's designed to give information that can be used later.