linux-kernel - Re: Possible bug report: kernel 6.5.0/6.5.1 high load when CIFS share is mounted (cifsd-cfid-laundromat in"D" state)

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Date:   Fri, 20 Oct 2023 12:40:54 +0200
From:   "Linux regression tracking #update (Thorsten Leemhuis)" 
        <regressions@...mhuis.info>
To:     Linux CIFS <linux-cifs@...r.kernel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Regressions <regressions@...ts.linux.dev>
Subject: Re: Possible bug report: kernel 6.5.0/6.5.1 high load when CIFS share
 is mounted (cifsd-cfid-laundromat in"D" state)

[TLDR: This mail in primarily relevant for Linux kernel regression
tracking. See link in footer if these mails annoy you.]

On 06.09.23 03:01, Bagas Sanjaya wrote:
> On Tue, Sep 05, 2023 at 01:09:05PM -0400, Brian Pardy wrote:
>> My apologies if I do not have the bug report protocol correct in posting here.
>>
>> I've noticed an issue with the CIFS client in kernel 6.5.0/6.5.1 that
>> does not exist in 6.4.12 or other previous kernels (I have not tested
>> 6.4.13). Almost immediately after mounting a CIFS share, the reported
>> load average on my system goes up by 2. At the time this occurs I see
>> two [cifsd-cfid-laundromat] kernel threads running the "D" state,
>> where they remain for the entire time the CIFS share is mounted. The
>> load will remain stable at 2 (otherwise idle) until the share is
>> unmounted, at which point the [cifsd-cfid-laundromat] threads
>> disappear and load drops back down to 0. This is easily reproducible
>> on my system, but I am not sure what to do to retrieve more useful
>> debugging information. If I mount two shares from this server, I get
>> four laundromat threads in "D" state and a sustained load average of
>> 4.
>>[...]
> Anyway, I'm adding it to regzbot:
> 
> #regzbot ^introduced: v6.4..v6.5
> #regzbot title: incorrect CPU utilization report (multiplied) when mounting CIFS

#regzbot fix: 2da338ff752a2789470
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
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