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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Message-ID: <CAO+kfxQtOKoKdb+LtMeFxgu8VXa73nbmTPSfscbdwjUXM7ME_A@mail.gmail.com>
Date:   Tue, 19 Sep 2023 09:21:33 -0400
From:   Brian Pardy <brian.pardy@...il.com>
To:     Steve French <smfrench@...il.com>
Cc:     Bagas Sanjaya <bagasdotme@...il.com>,
        Linux CIFS <linux-cifs@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Regressions <regressions@...ts.linux.dev>,
        Paulo Alcantara <pc@...guebit.com>,
        ronnie sahlberg <ronniesahlberg@...il.com>,
        Shyam Prasad N <nspmangalore@...il.com>,
        Bharath S M <bharathsm@...rosoft.com>
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)

On Tue, Sep 19, 2023 at 1:36 AM Steve French <smfrench@...il.com> wrote:
>
> Does the attached patch help in your case?  It avoids starting the
> laundromat thread for IPC shares (which cuts the number of the threads
> in half for many cases) and also avoids starting them if the server
> does not support directory leases (e.g. if Samba server instead of
> Windows server).

Hello,

I applied the 0001-smb3-do-not-start-laundromat-thread-when-dir-leases-.patch
you provided against the 6.5.3 kernel.

I can confirm that it resolves this issue - no laundromat threads are
created, and the reported load average is as expected, not falsely
high.

This appears to fully fix the issue in my case.  Thank you very much!

> On Mon, Sep 18, 2023 at 10:00 PM Steve French <smfrench@...il.com> wrote:
> >
> > Paulo and I were discussing the laundromat thread at the SMB3.1.1 test
> > event (at SDC this week) which is now going on - will let you know
> > what we find.
> >
> > One obvious thing is that it probably isn't necessary for cases when
> > the server does not support directory leases, but we noticed another
> > problem as well.