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Tue, 9 Dec 2025 15:45:05 -0500 (EST) Date: Tue, 9 Dec 2025 21:45:03 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Ariadne Conill Cc: v9fs@lists.linux.dev, xen-devel@lists.xenproject.org, asmadeus@codewreck.org, linux_oss@crudebyte.com, lucho@ionkov.net, ericvh@kernel.org, Juergen Gross , Stefano Stabellini , Alex Zenla Subject: Re: [PATCH] 9p/xen: mark 9p transport device as closing when removing it Message-ID: References: <20251208195155.27473-1-ariadne@ariadne.space> Precedence: bulk X-Mailing-List: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="MSfjrwLz2Q9UiVY0" Content-Disposition: inline In-Reply-To: <20251208195155.27473-1-ariadne@ariadne.space> --MSfjrwLz2Q9UiVY0 Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Tue, 9 Dec 2025 21:45:03 +0100 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: Ariadne Conill Cc: v9fs@lists.linux.dev, xen-devel@lists.xenproject.org, asmadeus@codewreck.org, linux_oss@crudebyte.com, lucho@ionkov.net, ericvh@kernel.org, Juergen Gross , Stefano Stabellini , Alex Zenla Subject: Re: [PATCH] 9p/xen: mark 9p transport device as closing when removing it On Mon, Dec 08, 2025 at 11:51:55AM -0800, Ariadne Conill wrote: > We need to do this so that we can signal to the other end that the > device is being removed, so that it will release its claim on the > underlying memory allocation. Otherwise releasing the grant-table > entries is deferred resulting in a kernel oops since the pages have > already been freed. >=20 > Cc: Juergen Gross > Cc: Stefano Stabellini > Fixes: 71ebd71921e45 ("xen/9pfs: connect to the backend") > Signed-off-by: Ariadne Conill > Signed-off-by: Alex Zenla > --- > net/9p/trans_xen.c | 1 + > 1 file changed, 1 insertion(+) >=20 > diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c > index b9ff69c7522a..cde283c42dc6 100644 > --- a/net/9p/trans_xen.c > +++ b/net/9p/trans_xen.c > @@ -312,6 +312,7 @@ static void xen_9pfs_front_remove(struct xenbus_devic= e *dev) > { > struct xen_9pfs_front_priv *priv =3D dev_get_drvdata(&dev->dev); > =20 > + xenbus_switch_state(dev, XenbusStateClosing); I think you need to wait for the backend to acknowledge it by switching its state, before continuing. See for example xennet_remove()->xennet_bus_close() in drivers/net/xen-netfront.c. > dev_set_drvdata(&dev->dev, NULL); > xen_9pfs_front_free(priv); > } > --=20 > 2.52.0 >=20 >=20 --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --MSfjrwLz2Q9UiVY0 Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmk4ik8ACgkQ24/THMrX 1yxxdwf9EtdVm4vHKrR6Wilq1Fv0h4VXkAx3qT3t0DLPbOJ19GflMTaV5cVPgUQA OzoCxGYOPjZHIDSkUDjoPrmWWs1al22S8jwB5JtD6ep/i5XX0tWY06SeuwEouXvt DxFnZDg9DD7LzMd5MC4DDjv1y1TuR7tP7QYjKYrX6sFxRn0lQqEcS7YLZRdDRGXk LZtgL9hb4LjG5EChL+i9ipHk2FhXbj8McsnwbhLQDgSoIM7BFUQ3m2Qk8gDKAagy fYVXlkhwy+quQFJoirM7qKsuUkkMPTbdxtmbJTSRTf7VM+DxK57KMghL8Ocsmmn2 jBYyH9svOnzBj/ZJL4iIIAfnjxndwg== =VcHR -----END PGP SIGNATURE----- --MSfjrwLz2Q9UiVY0--