linux-kernel - Re: regression: nfs mount (even idle) eventually hangs server

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Date:   Thu, 22 Dec 2022 04:28:17 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Mike Galbraith <efault@....de>
CC:     LKML <linux-kernel@...r.kernel.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: regression: nfs mount (even idle) eventually hangs server



> On Dec 21, 2022, at 11:14 PM, Mike Galbraith <efault@....de> wrote:
> 
> On Thu, 2022-12-22 at 04:42 +0100, Mike Galbraith wrote:
>> On Wed, 2022-12-21 at 10:56 +0100, Mike Galbraith wrote:
>>>> 6.1 didn't reproduce either, so it would appear to be a merge window bug.
>> 
>> Ah, not true, turning evolution loose in nfs mounted home and letting
>> it refresh mailboxes while desktop box was kept busy jammed up 6.1.0 in
>> fairly short order.  
> 
> Well crap.  That was _not_ virgin 6.1.0 after all, it was 6.1.0 with...
> 
> 44df6f439a17 NFSD: add delegation reaper to react to low memory condition
> 3959066b697b NFSD: add support for sending CB_RECALL_ANY
> a1049eb47f20 NFSD: refactoring courtesy_client_reaper to a generic low memory shrinker
> 
> ...applied from poking about yesterday.  I had given up on those as
> culprit, and intended to pop them off and rebuild, but they were in
> fact in the booted kernel.  Oh well, booboo could have a bright side.

Hi Mike-

I'm guessing your client mounts with NFSv4.x.

We've been chasing a similar problem for a few months, but for
lack of a solid reproducer, it has remained elusive.

We believe the problem was introduced between 5.19 and 6.0. If
you have a fairly reliable way to trigger the server hang, then
maybe a bisect would be possible?


--
Chuck Lever