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From:   Daire Byrne <daire@dneg.com>
Date:   Wed, 7 Jul 2021 23:21:28 +0100
Message-ID: <CAPt2mGPSeK6YHPQ8r6Z0UJv4mJnRAcEEc4VmLaENo91-K8P=fQ@mail.gmail.com>
Subject: Re: [PATCH/rfc v2] NFS: introduce NFS namespaces.
To:     NeilBrown <neilb@suse.de>
Cc:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <Anna.Schumaker@netapp.com>,
        linux-nfs <linux-nfs@vger.kernel.org>
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On Wed, 7 Jul 2021 at 22:25, NeilBrown <neilb@suse.de> wrote:
>
> On Wed, 07 Jul 2021, Daire Byrne wrote:
> > I stripped out all my patches so it's just this one on top of 5.13-rc7
> > and I can still reproduce it.
> >
> > I can only trigger it by mounting the same export (RHEL7 server) using
> > two different namespaces and performing a heavy IO benchmark to either
> > mount (leaving one idle). Part of the benchmark walks thousands of
> > dirs with files (hence the readdirs).
> >
> > If I mount the same server twice with no (same) namespaces, even with
> > the patch applied, it works fine without any crash.
>
> That's pretty solid evidence!
>
> I just realized that the stack trace you reported mentions
> "kfree_const()".
> My latest patch doesn't include that, and nfs doesn't use it at all.
> Might you still be using the older patch?
>
> NeilBrown

Oh... the last stack trace, the readdir one? I don't see kfree_const
myself but I may have a case of word blindness. The first one I
reported definitely has kfree_const but after your latest patch, this
last one around readdir doesn't seem to?

I'm pretty sure I have your latest patch (with kfree instead of
kfree_const) correctly applied. Though, I will double check that the
correct kernel and modules were then installed properly on my test VM.

Daire