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Mon, 9 Feb 2026 17:27:28 +0000 (GMT) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 09 Feb 2026 18:27:23 +0100 Message-Id: Subject: Re: [PATCH v1 2/3] KVM: s390: vsie: Fix race in walk_guest_tables() From: "Christoph Schlameuss" Cc: , , , , , , , , , , , , , , To: "Claudio Imbrenda" , X-Mailer: aerc 0.21.0 References: <20260206143553.14730-1-imbrenda@linux.ibm.com> <20260206143553.14730-3-imbrenda@linux.ibm.com> In-Reply-To: <20260206143553.14730-3-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=KZnfcAYD c=1 sm=1 tr=0 ts=698a1906 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VnNF1IyMAAAA:8 a=wnmpZm2sU0XAGl87Tm0A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjA5MDE0NSBTYWx0ZWRfX3eSvy7kgsDGE 5c+Rq2znMuSdlAiq/Ueh5fXZHhKTkRmF6Pznam9HcWPud1qnfqXRTpXlqe3RW+rAfz2Ononxd6z gp7kmdy4ZhUYmmrjLaeQGMx3edBBUk0YDJ2UD2qc9OyyAiUrC7kgF5gLePIN0Jioc5CysU341Ei 3i6ahkdEPma20n2cVFIskXUkE15kHfZAT+P5G0n2WxLV0OO0UFiwN7kthv4ImjjzsyS9TsQwmhS HcimwgqVO4kmU/i3vwTrvEnfE8mG46J5UcmgyCd5d9lHLkCZKQcXhB/LZ9ZHHAK5ErIo9YdQC5p E1vaNEutMjiJDq32AzYn+CYZYFO6uiIXODGJRuFK7v+V4PPGxMWsPUK9kaZKdyWTg142or1ODi8 sMaw+FXhq/OJxq2QavEOjsiDl4D2HGhfHP2znsTBG0uV2S33rhp0UL+PZ0Z4nVf7Z3nIAyEM6jz p1yTvznwy5ptWmbT8uw== X-Proofpoint-ORIG-GUID: 3w_4AReP9Y8KTdOn9TF0dBlWqjnEO1Wx X-Proofpoint-GUID: 3w_4AReP9Y8KTdOn9TF0dBlWqjnEO1Wx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-09_01,2026-02-09_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 adultscore=0 clxscore=1015 suspectscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602090145 On Fri Feb 6, 2026 at 3:35 PM CET, Claudio Imbrenda wrote: > It is possible that walk_guest_tables() is called on a shadow gmap that > has been removed already, in which case its parent will be NULL. > > In such case, return -EAGAIN and let the callers deal with it. > > Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") > Signed-off-by: Claudio Imbrenda Reviewed-by: Christoph Schlameuss > --- > arch/s390/kvm/gaccess.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c > index 67de47a81a87..4630b2a067ea 100644 > --- a/arch/s390/kvm/gaccess.c > +++ b/arch/s390/kvm/gaccess.c > @@ -1287,7 +1287,10 @@ static int walk_guest_tables(struct gmap *sg, unsi= gned long saddr, struct pgtwal > union asce asce; > int rc; > =20 > + if (!parent) > + return -EAGAIN; > kvm =3D parent->kvm; > + WARN_ON(!kvm); > asce =3D sg->guest_asce; > entries =3D get_entries(w); > =20