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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Nikos Tsironis <ntsironis@arrikto.com>
CC:     "trondmy@kernel.org" <trondmy@kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH] nfsd: Ensure knfsd shuts down when the "nfsd" pseudofs is
 unmounted
Thread-Topic: [PATCH] nfsd: Ensure knfsd shuts down when the "nfsd" pseudofs
 is unmounted
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Date:   Thu, 22 Dec 2022 14:48:59 +0000
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[ Cc: Bruce removed because that address no longer works ]

> On Dec 20, 2022, at 8:43 AM, Nikos Tsironis <ntsironis@arrikto.com> wrote=
:
>=20
> On 3/13/21 23:08, trondmy@kernel.org wrote:
>> From: Trond Myklebust <trond.myklebust@hammerspace.com>
>> In order to ensure that knfsd threads don't linger once the nfsd
>> pseudofs is unmounted (e.g. when the container is killed) we let
>> nfsd_umount() shut down those threads and wait for them to exit.
>> This also should ensure that we don't need to do a kernel mount of
>> the pseudofs, since the thread lifetime is now limited by the
>> lifetime of the filesystem.
>> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
>> ---
>=20
> Hello,
>=20
> This patch was merged in kernel v5.13, but the issue exists in older
> kernels too.
>=20
> Is there a reason that the patch was never backported to older stable
> kernels?

Hello Nikos-

A probable reason is there is no Fixes: or Cc: stable@vger tag in the
merged commit, so it will not be cherry-picked by AUTOSEL. Another
reason might be that the patch does not apply cleanly to LTS kernels.

You can make a request to stable@ for this patch to be backported, but
I would prefer if you apply the patch and test it on each target kernel
before making such a request. Or, you can pick which LTS kernel(s) are
most relevant to you and ask for backport to only those.

A good test will have three parts:

- Make a positive confirmation the issue exists in that kernel

- Make sure the patch applies cleanly verbatim and causes no regression

- Make sure the patch fixes the issue in that kernel

It's a bit of (albeit mechanical) effort, and the Linux NFS community
doesn't have the resources to manage it for all patches going into
mainline to six different LTS kernels.


--
Chuck Lever