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Wed, 3 Jun 2026 09:55:39 +0000 (GMT) From: Shrikanth Hegde To: maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Cc: sshegde@linux.ibm.com, peterz@infradead.org, tglx@kernel.org, christophe.leroy@csgroup.eu, linux-kernel@vger.kernel.org, venkat88@linux.ibm.com, mkchauras@gmail.com Subject: [PATCH] powerpc/entry: Disable interrupts before irqentry_exit Date: Wed, 3 Jun 2026 15:25:21 +0530 Message-ID: <20260603095521.198267-1-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=Zt3d7d7G c=1 sm=1 tr=0 ts=6a1ffa24 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=ZcPFttQkb1t9wctH9vwA:9 X-Proofpoint-GUID: 4SRcU2V-rmNWWlu_PJO-ZdMYeSVQnTs9 X-Proofpoint-ORIG-GUID: UrbO6C0mW4RdetaAR0QuhswaWa4j37cT X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjAzMDA5MiBTYWx0ZWRfX7dOtxJV8PCDh SHkSKZHqoQfEQ0QNxTD00VV62LJUaklaOcZVaRGYWc9x2o8g4zFqUqvf+fPawqt7to4qTxiWwbK VCfuwa/JoP6ulZK2OzvD9x1K6dTJGX5vv0odGq8UTxPKlKdUqcX+MX+khDRGf+7SiLwzljbdsOQ L9TG1ZJrS/DtVj5jNjZi0Dcy+eMaa4kiJl0VtrwdeC8+D/qeZQCM95rTHoSn5QXUfyVRpOYhqWL yRUs0xm3C8p6roI0itssNsl0e/1Kk4RMmbsKLrNxczOIF4yxK1evSpRuYiIgNUMuABrVNhS9PdA 6opHeOQn/JQHOOAI+dw5RzirXxtQTJa3YsuQGwdEVEYESthWbAPSMCSYmO6DWDNcCHqoF9ANVxo Ca75QW3uIcb0rZ8XgKyeYIBdl3QI8KIF1niQ3IwWSZG3SStC7DySH4NYMpSfVAbl89zq6sNVB5j ybA0MpVDKpTY0Mz1lVw== 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_03,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 phishscore=0 spamscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606030092 Content-Type: text/plain; charset="utf-8" Venkat reported a panic on powerpc-next tree where GENERIC_ENTRY has been enabled. kernel BUG at kernel/sched/core.c:7512! NIP preempt_schedule_irq+0x44/0x118 LR dynamic_irqentry_exit_cond_resched+0x40/0x1a4 Call Trace: dynamic_irqentry_exit_cond_resched+0x40/0x1a4 do_page_fault+0xc0/0x104 data_access_common_virt+0x210/0x220 This happens since __do_page_fault ends up enabling the interrupts and it could take significant time such that need_resched could be set. This leads to schedule call in irqentry_exit leading to the bug. There are many such irq handlers which enables the interrupts. Fix it by disabling the irq before calling irqentry_exit. The same pattern exists today in interrupt_exit_kernel_prepare. While there, make those BUG_ON into WARN_ON. Interrupt is disabled right after so it is not that severe. This will still help to catch the offending callsites. Fixes: bee25f97ad24 ("powerpc: Enable GENERIC_ENTRY feature") Reported-by: Venkat Rao Bagalkote Closes: https://lore.kernel.org/all/7904105b-9dfa-4efd-a5ef-bc0276ed255d@li= nux.ibm.com/ Signed-off-by: Shrikanth Hegde --- This applies on top on powerpc/next tree. base: 6ed60999d33d '("powerpc: Remove unused functions")' arch/powerpc/include/asm/entry-common.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/entry-common.h b/arch/powerpc/include= /asm/entry-common.h index de5601282755..7da373a56813 100644 --- a/arch/powerpc/include/asm/entry-common.h +++ b/arch/powerpc/include/asm/entry-common.h @@ -253,16 +253,17 @@ static inline void arch_interrupt_enter_prepare(struc= t pt_regs *regs) static inline void arch_interrupt_exit_prepare(struct pt_regs *regs) { if (user_mode(regs)) { - BUG_ON(regs_is_unrecoverable(regs)); - BUG_ON(regs_irqs_disabled(regs)); + WARN_ON(regs_is_unrecoverable(regs)); + WARN_ON(regs_irqs_disabled(regs)); /* * We don't need to restore AMR on the way back to userspace for KUAP. * AMR can only have been unlocked if we interrupted the kernel. */ kuap_assert_locked(); - - local_irq_disable(); } + + /* irqentry_exit expects to be called with interrupts disabled */ + local_irq_disable(); } =20 static inline void arch_interrupt_async_enter_prepare(struct pt_regs *regs) --=20 2.47.3