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Date: Mon, 10 Jun 2024 13:15:07 -0600
From: Keith Busch <kbusch@kernel.org>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, sachinp@linux.vnet.com
Subject: Re: Kernel OOPS while creating a NVMe Namespace
Message-ID: <ZmdQuz8vJZMj41Kn@kbusch-mbp.dhcp.thefacebook.com>
References: <2312e6c3-a069-4388-a863-df7e261b9d70@linux.vnet.ibm.com>
 <ZmdLlaVO-QUug5aj@kbusch-mbp.dhcp.thefacebook.com>
 <e8fa4c36-49e5-40b8-9cea-6b3b61aa3240@grimberg.me>
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On Mon, Jun 10, 2024 at 10:05:00PM +0300, Sagi Grimberg wrote:
> 
> 
> On 10/06/2024 21:53, Keith Busch wrote:
> > On Mon, Jun 10, 2024 at 01:21:00PM +0530, Venkat Rao Bagalkote wrote:
> > > Issue is introduced by the patch: be647e2c76b27f409cdd520f66c95be888b553a3.
> > My mistake. The namespace remove list appears to be getting corrupted
> > because I'm using the wrong APIs to replace a "list_move_tail". This is
> > fixing the issue on my end:
> > 
> > ---
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index 7c9f91314d366..c667290de5133 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -3959,9 +3959,10 @@ static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl,
> >   	mutex_lock(&ctrl->namespaces_lock);
> >   	list_for_each_entry_safe(ns, next, &ctrl->namespaces, list) {
> > -		if (ns->head->ns_id > nsid)
> > -			list_splice_init_rcu(&ns->list, &rm_list,
> > -					     synchronize_rcu);
> > +		if (ns->head->ns_id > nsid) {
> > +			list_del_rcu(&ns->list);
> > +			list_add_tail_rcu(&ns->list, &rm_list);
> > +		}
> >   	}
> >   	mutex_unlock(&ctrl->namespaces_lock);
> >   	synchronize_srcu(&ctrl->srcu);
> > --
> 
> Can we add a reproducer for this in blktests? I'm assuming that we can
> easily trigger this
> with adding/removing nvmet namespaces?

I'm testing this with Namespace Manamgent commands, which nvmet doesn't
support. You can recreate the issue by detaching the last namespace.