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Wed, 29 Jul 2026 10:16:47 +0000 (GMT) Received: from [9.43.93.217] (unknown [9.43.93.217]) by smtpav05.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Jul 2026 10:16:47 +0000 (GMT) Message-ID: <8dda7a5a-96ed-4a80-a6db-c01434ae897c@linux.ibm.com> Date: Wed, 29 Jul 2026 15:46:45 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc/970: fix nap return address corruption on async interrupt exit To: Thorsten Leemhuis , mpe@ellerman.id.au, npiggin@gmail.com Cc: thuth@redhat.com, "Mukesh Kumar Chaurasiya (IBM)" , mchauras@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, ruanjinjie@huawei.com, linux-kernel@vger.kernel.org, Andreas Schwab , John Ogness , chleroy@kernel.org, sshegde@linux.ibm.com, Linux kernel regressions list References: <20260707172430.790040-1-mkchauras@gmail.com> <87fr1iq4fu.fsf@jogness.linutronix.de> <87h5lpq5x4.fsf@jogness.linutronix.de> <67fd0bdf-237e-41d0-aa02-62ca2736942a@leemhuis.info> Content-Language: en-US From: Madhavan Srinivasan In-Reply-To: <67fd0bdf-237e-41d0-aa02-62ca2736942a@leemhuis.info> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI5MDA4MCBTYWx0ZWRfX1oWG6KpaOO4p HTDJO7VNOHX15N4Ucl0MdYqhhdcbrrz9IR+uJJnEj7ebSk+PXIn1hRe/jBZ1O3vDnJ4Ul7lw8y3 nT0CDLnIXJ2tlzarDwJ5kCUwwMZqT3Q= X-Proofpoint-GUID: 7Hboy94Y4Ck0oYSENYbI1NMCcQoGDA2m X-Proofpoint-ORIG-GUID: lzw0ZbpeEKtXZ69xUbTD4D8wvA1zWI6h X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI5MDA4MCBTYWx0ZWRfXzTi0LTZI7IWl SYZ9m15CPs90T6e0eCSN9NZ+gJZcxYe6SkU5bm9M/DWAc4orXYmz9yvJ+Li39WsblizBgk7hhxc IGPIpHwthTOmo5lkK+S57f05W/1WCtLx/zXim9a8vDOCaQFSdhS3SFq0F1TOzW33PY3pic50HXY W6Pb9gtWTBvXJStpq6iFSdho6KC5PDG9idylIZDz/HwrGpv7mDPaU30TmMdXQIzxJw+gg8bRdtF hYtpSd9347LheiALFTKBpp1ygd1kpRA8M9d6SqgeZXy33rxlERT82QG5+DfcFx6H9rztOP1yZwo AghhkL7LVxOtVxwopNqjb4oxGSDjWAYjq85IPCWYgIFs+TWueDwUz6F1qHHT/NN3P/jmjnPE1+y XJhPx5FtS4IRQTct/ASceUqdARbAF0fuop0FcTbcsrlj9hwZJKGISJyncIxTN3f0jajv3UbiIQ2 L2DEzjuF/55O7ALQFtw== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a69d319 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=tBb2bbeoAAAA:8 a=htZlTOaOdGbwrN_0Y0cA:9 a=QEXdDO2ut3YA:10 a=Oj-tNtZlA1e06AYgeCfH:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-29_03,2026-07-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607290080 On 7/29/26 2:27 PM, Thorsten Leemhuis wrote: > On 7/23/26 13:52, John Ogness wrote: >> On 2026-07-16, John Ogness wrote: >>> On 2026-07-07, "Mukesh Kumar Chaurasiya (IBM)" wrote: >>>> On PowerMac G5 (PPC970, CONFIG_PPC_970_NAP) the system panics shortly >>>> after boot with symptoms including instruction fetch faults, kernel data >>>> access faults, and stack corruption, predominantly on SMP and always >>>> somewhere inside softirq processing. >>>> [...] >>>> Fix this by calling nap_adjust_return() inside DEFINE_INTERRUPT_HANDLER_ASYNC >>>> immediately before irq_exit_rcu(), ensuring _TLF_NAPPING is cleared and >>>> regs->NIP is adjusted before any code that can re-enable interrupts or >>>> invoke softirqs runs. Move the explanatory comment into >>>> nap_adjust_return() itself and remove it from arch_interrupt_async_exit_prepare(). >>>> >>>> Fixes: bee25f97ad24 ("powerpc: Enable GENERIC_ENTRY feature") >>>> Closes: https://lore.kernel.org/all/87wlvazrdy.fsf@igel.home/ >>>> Reported-by: Andreas Schwab >>>> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) >>> Tested-by: John Ogness >> Is there a reason this is not being queued for 7.2? Without this fix, >> PPC970 machines cannot boot 7.2. > Wondering the same. Quick reminder: Linus afaik wants all regressions > ideally be fixed by -rc6. So it would be good to get this mainlined > within the next few days -- unless of course there is a reason why this > fix is a bad idea. Is there? I have added this to my fixes-test and will pull this as part of upcoming fixes PR Maddy > > Ciao, Thorsten