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Wed, 25 Feb 2026 18:30:13 +0000 (GMT) Message-ID: <08307223-88ad-4550-963e-5d1ee315023c@linux.ibm.com> Date: Wed, 25 Feb 2026 13:30:13 -0500 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] sched: Further restrict the preemption modes To: Christian Borntraeger , Ilya Leoshkevich , Ciunas Bennett , Peter Zijlstra , mingo@kernel.org, Thomas Gleixner , Sebastian Andrzej Siewior Cc: juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, clrkwllms@kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Linus Torvalds , linux-s390@vger.kernel.org, Matthew Rosato , Hendrik Brueckner References: <20251219101502.GB1132199@noisy.programming.kicks-ass.net> <182f110b-ac63-4db4-8b01-0e841639bc39@linux.ibm.com> Content-Language: en-US From: Douglas Freimuth In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: _0UMUoKIZlKOKqau5XTtb0XTWq94cAbn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI1MDE3NCBTYWx0ZWRfX5hzxm1BQVqPQ FGBk6ZpsteTOtLR+qOOvnM7R1Pnx3O1g2NTK0XK/e+EVxWjmAPdRrjmfWb2ISMfhn/2sYt4nr3B OI+Xh7TjlzW02J38u/lQoMB3U8wBrxZcXzVIpkUubfXFNYIgVd2I9uTQ8GVLdsDfux1LnjtTJua o1jG+m7XT4X1qF6G5HUt7i0Q/uaYE8GMnkz/210nVH2x9i1xn2b9d0P2A3VP04KjvQWaql2WIgV d3TRrZrkkH+Hl05em2OUxd6Fmiv3RY4/tQCOlLxVWUJKuXA81e3Td9o65CG6YBD5UPAEvDAOO5E 2Yg0ACUPu6qvQgS4TBvlJNCkYGy5EU2Hl13u0CPOPGUH7ZmollwyqqxIFNomN72w7wlm0hPFuBo 6fJMs2vLCQwywDeBPYuymJXMwUr/FJLcRvQWDNFTpAEGO+bO0FGJpNeJXfImIMpfSRoaFPPQGWe MSvDdxHHfLTGY1rMb8A== X-Authority-Analysis: v=2.4 cv=eNceTXp1 c=1 sm=1 tr=0 ts=699f3fba cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=0MXMk1mwkTAisRVsYMEA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: LnQXTQu1zciqhCL8NCZSCXgSM0NrDEL0 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=2026-02-25_02,2026-02-25_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 priorityscore=1501 phishscore=0 suspectscore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 malwarescore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602250174 On 2/25/26 11:33 AM, Christian Borntraeger wrote: > Am 24.02.26 um 21:30 schrieb Ilya Leoshkevich: >> Finally, what is the worker doing? I looked at __queue_work() kstacks, >> and they all come from irqfd_wakeup(). >> >> irqfd_wakeup() calls arch-specific kvm_arch_set_irq_inatomic(), which >> is implemented on x86 and not implemented on s390. >> >> >> This may explain why we on s390 are the first to see this. >> >> >> Christian, do you think if it would make sense to >> implement kvm_arch_set_irq_inatomic() on s390? > > So in fact Doug is working on that at the moment. There are some corner > cases where we had concerns as we have to pin the guest pages holding > the interrupt bits. This was secure execution, I need to followup if > we have already solved those cases. But we can try if the current patch > will help this particular problem. > > If yes, then we can try to speed up the work on this. > > Christian Christian, the patch is very close to ready. The last step, I rebased on Master today to pickup the latest changes to interrupt.c. I am building that now and will test for non-SE and SE environments. I have been testing my solution for SE environments for a few weeks and it seems to cover the use cases I have tested.