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Wed, 3 Jun 2026 06:16:53 +0000 (GMT) Message-ID: <7d7c24d7900a30f53820feae952e2c2bd92d0a42.camel@linux.ibm.com> Subject: Re: [PATCH 0/3] powerpc: fix preempt_count imbalances in perf and kexec paths From: Aboorva Devarajan To: Shrikanth Hegde , Madhavan Srinivasan , linuxppc-dev@lists.ozlabs.org Cc: Athira Rajeev , Christophe Leroy , linux-kernel@vger.kernel.org, Sourabh Jain , Ritesh Harjani Date: Wed, 03 Jun 2026 11:46:52 +0530 In-Reply-To: <0c6d2855-61df-4fd2-bede-0c204f4fd2b1@linux.ibm.com> References: <20260518050855.1147242-1-aboorvad@linux.ibm.com> <0c6d2855-61df-4fd2-bede-0c204f4fd2b1@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (3.60.1-1.fc44) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: s13eGU7E7RevYS-DINJTz19-UrQ8R0ih X-Proofpoint-GUID: T9YiJhovfMG7_oLb5jfUlzOXhombNN_c X-Authority-Analysis: v=2.4 cv=bcVbluPB c=1 sm=1 tr=0 ts=6a1fc6de cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=SyrEavi5T-EveYA-VyoA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjAzMDA1NiBTYWx0ZWRfX7ytuOsw+Sav8 X3q+LyHB3JRW9J9e1nbOKYhsQ1Tr9O54SXqhd0x4/7nE9c0baYkeLJFPbcY48IYB/3eIfnBr9Kq ei4z2p1fo9qL9Yi3ilCnlCbJnklEyfvApjRClGP0LQyO5riWek7VBBdixTaQc43h63UyuP/vl+E GfFo7Ndl0hx7feXGWd6CDxzyIUcc9wdeu73AT0wZRB9y447sLYxxZYdXA9uLqfu3wKA5pPO3JYY BEFqt55BNkdxftf7ufn+zO7UFwHLe78wEQzB6mWlCVyi4uZo8KR2eOsQtOIqcp3s+q/uYS2JwDN T2h2NqyHsV+DOicAlxsFbQ3q3Yj57IeooWFoCMm3zMupeSIZU8LF7qGSo+HvzwhMw9qbXwalzvn b62GZIewPrZMDoWCVQZxsSZaaGcd0JTkAAcO730rk/CcR67DvCloPkWi1d5sI/5H1RU19YSvRS7 kNGjcIXrNEmtMo6Ua4A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-03_02,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 adultscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606030056 On Mon, 2026-05-18 at 13:38 +0530, Shrikanth Hegde wrote: > Hi Aboorva, >=20 > On 5/18/26 10:38 AM, Aboorva Devarajan wrote: > > Hi all, > >=20 > > This patch series fixes some minor preempt_count bookkeeping issues in > > arch/powerpc/ found during a preemption leak audit prompted by the > > lazy/full preemption model changes. These are get_cpu/put_cpu and > > get_cpu_var/put_cpu_var pairing errors that leave preempt_count > > incorrectly elevated or underflowed. > >=20 >=20 > Thanks for fixing some of these. >=20 > while we do this, Can you fix these mismatch in preempt disable/enable in > below files as well. >=20 > 1. kernel/kprobes.c - kprobe_handler - Does disable, but doesn't enable i= n some return paths. > =C2=A0=C2=A0=C2=A0 A definite leak. >=20 > 2. Maybe platforms/pseries/lpar.c and platforms/powernv/opal-tracepoints.= c. > =C2=A0=C2=A0=C2=A0 In __trace_hcall_entry/exit.=C2=A0 It maybe a very cor= ner case, > =C2=A0=C2=A0=C2=A0 I don't see a big concern there. But it may be remotel= y possible. > =C2=A0=C2=A0=C2=A0 Need to evaluate whether it should be fixed or not. Thanks for the pointers. I'll go through these and get back. Regards, Aboorva