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Tue, 24 Mar 2026 15:29:01 +0000 (GMT) Date: Tue, 24 Mar 2026 16:28:58 +0100 From: Claudio Imbrenda To: Janosch Frank Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, gra@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com, david@kernel.org Subject: Re: [PATCH v2 6/8] KVM: s390: vsie: Fix unshadowing while shadowing Message-ID: <20260324162858.0e305fc6@p-imbrenda> In-Reply-To: <67810b81-a3d0-4517-96d2-e99b90a216cd@linux.ibm.com> References: <20260320161542.202913-1-imbrenda@linux.ibm.com> <20260320161542.202913-7-imbrenda@linux.ibm.com> <67810b81-a3d0-4517-96d2-e99b90a216cd@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: MLzhcKOzz0SzUIwCmYoGHwrty6FcQ-8L X-Authority-Analysis: v=2.4 cv=aMr9aL9m c=1 sm=1 tr=0 ts=69c2adc3 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=kj9zAlcOel0A:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=rh5d3bxwEoKsl6cgku0A:9 a=CjuIK1q_8ugA:10 a=ZXulRonScM0A:10 a=zZCYzV9kfG8A:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI0MDExOSBTYWx0ZWRfX6F8d61Io7YZB jZm/BM7OCQoW5WZ2YYiFgG9SHgmsgbdP9YsZky29bt2AK9hByR9opQThcO0WUxoFdwB9TZyLQYb J/dqTjgefTx8+U+DTC2ylLrvLUKGKA1/RygQ8inGirv8O41GVPE9Ww8Hs0C3EXVGVMxpAC8CIBD MfBac9S6utul/qE7dP1S2xZQ4SbhqkmoenKKkF6l9YFyBL7Xfosm3ex4a0acHe7F6JFuQFh7Oyl Qo3EBkKfASO4U8mfMOe1HLylNq/gd3l5PKpRPv/WZ/Tb9E6dp2O/Pdnfji2IcOLMrDaBhJMKXNP 10+xEWWdaC93+riF16KcmbMqiKASju0O+2hdMD8qXB4TQeQEHyC6dUXclHLNTZEtnyQaY/pNr7/ 0rHLiOjJ9T3MPo9fo7m4ZWyRK6ZIrJRPQ0mkQI/C2pclT/VJBcm9tNfBVJG/3P11eySTqwSNiCU YW39Tr+sDJKL3bNujNw== X-Proofpoint-GUID: MLzhcKOzz0SzUIwCmYoGHwrty6FcQ-8L X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-24_03,2026-03-23_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 malwarescore=0 suspectscore=0 phishscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603240119 On Tue, 24 Mar 2026 15:52:02 +0100 Janosch Frank wrote: > On 3/20/26 17:15, Claudio Imbrenda wrote: > > If shadowing causes the shadow gmap to get unshadowed, exit early to > > How can this happen? one possibility is if g2 maps g3 memory pages over the top-level table of the g2 -> g3 asce there are probably other cases I can't think of > > > prevent an attempt to dereference the parent pointer, which at this > > point is NULL. > > > > Opportunistically add some more checks to prevent NULL parents.