netdev - Re: [BUG] mlx5_core general protection fault in mlx5_cmd_comp

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Date:   Thu, 13 Oct 2022 13:27:38 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Jinpu Wang <jinpu.wang@...os.com>
Cc:     netdev <netdev@...r.kernel.org>,
        RDMA mailing list <linux-rdma@...r.kernel.org>,
        Moshe Shemesh <moshe@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Tariq Toukan <tariqt@...dia.com>,
        Maor Gottlieb <maorg@...dia.com>, Shay Drory <shayd@...dia.com>
Subject: Re: [BUG] mlx5_core general protection fault in mlx5_cmd_comp_handler

On Thu, Oct 13, 2022 at 10:32:55AM +0200, Jinpu Wang wrote:
> On Thu, Oct 13, 2022 at 10:18 AM Leon Romanovsky <leon@...nel.org> wrote:
> >
> > On Wed, Oct 12, 2022 at 01:55:55PM +0200, Jinpu Wang wrote:
> > > Hi Leon, hi Saeed,
> > >
> > > We have seen crashes during server shutdown on both kernel 5.10 and
> > > kernel 5.15 with GPF in mlx5 mlx5_cmd_comp_handler function.
> > >
> > > All of the crashes point to
> > >
> > > 1606                         memcpy(ent->out->first.data,
> > > ent->lay->out, sizeof(ent->lay->out));
> > >
> > > I guess, it's kind of use after free for ent buffer. I tried to reprod
> > > by repeatedly reboot the testing servers, but no success  so far.
> >
> > My guess is that command interface is not flushed, but Moshe and me
> > didn't see how it can happen.
> >
> >   1206         INIT_DELAYED_WORK(&ent->cb_timeout_work, cb_timeout_handler);
> >   1207         INIT_WORK(&ent->work, cmd_work_handler);
> >   1208         if (page_queue) {
> >   1209                 cmd_work_handler(&ent->work);
> >   1210         } else if (!queue_work(cmd->wq, &ent->work)) {
> >                           ^^^^^^^ this is what is causing to the splat
> >   1211                 mlx5_core_warn(dev, "failed to queue work\n");
> >   1212                 err = -EALREADY;
> >   1213                 goto out_free;
> >   1214         }
> >
> > <...>
> > >
> > > Is this problem known, maybe already fixed?
> >
> > I don't see any missing Fixes that exist in 6.0 and don't exist in 5.5.32.

Sorry it is 5.15.32

> > Is it possible to reproduce this on latest upstream code?
> I haven't been able to reproduce it, as mentioned above, I tried to
> reproduce by simply reboot in loop, no luck yet.
> do you have suggestions to speedup the reproduction?

Maybe try to shutdown during filling command interface.
I think that any query command will do the trick.

> Once I can reproduce, I can also try with kernel 6.0.

It will be great.

Thanks