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Tue, 09 Jun 2026 09:17:19 -0700 (PDT) Received: from [192.168.1.167] ([185.168.96.228]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490be1f69bcsm532407115e9.8.2026.06.09.09.17.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2026 09:17:18 -0700 (PDT) Message-ID: Subject: Re: [PATCH] rqspinlock: Fix order in raw_res_spin_(un)lock_irq to allow schedule From: Gabriele Monaco To: Kumar Kartikeya Dwivedi , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , bpf@vger.kernel.org, Linux-Arch , linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long Date: Tue, 09 Jun 2026 18:17:17 +0200 In-Reply-To: References: <20260609094941.56122-1-gmonaco@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-06-09 at 16:42 +0200, Kumar Kartikeya Dwivedi wrote: > On Tue Jun 9, 2026 at 3:04 PM CEST, Gabriele Monaco wrote: > > On Tue, 2026-06-09 at 13:22 +0200, Arnd Bergmann wrote: > >=20 > > > Did you see this cause measurable performance problems, > > > or did you find it through inspection? > >=20 > > I noticed it while debugging an ENOMEM issue in the test_maps BPF > > selftest on PREEMPT_RT and this was an obvious cuplrit (irq_work > > not scheduled during a stress run). Turns out the problem is still > > there after this fix though. >=20 > I would imagine this to be the least of your problems, I think > there's a bunch of blockers for complete selftests passing with > PREEMPT_RT support in BPF. >=20 Well, I'm starting to believe that too.. At the moment on well tuned machines we are only observing ENOMEM issues in the test_maps and only when it's literally hogging the allocator (preallocation is off and 100 treads do updates in parallel). What else are you expecting to fail under PREEMPT_RT? > > > > Signed-off-by: Gabriele Monaco > > >=20 > > > Acked-by: Arnd Bergmann # asm-generic >=20 > The patch makes sense to me as well. >=20 > Acked-by: Kumar Kartikeya Dwivedi Thanks, Gabriele