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Wed, 25 Feb 2026 16:33:32 +0000 (GMT) Message-ID: Date: Wed, 25 Feb 2026 11:33:31 -0500 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] sched: Further restrict the preemption modes To: 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, Douglas Freimuth , 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: Christian Borntraeger In-Reply-To: Content-Type: text/plain; charset=UTF-8; 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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