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Wed, 11 Nov 2026 18:40:34 -0800 (PST) Received: from thinkpad.tail59a646.ts.net ([112.199.224.229]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5b1003fsm19000961c88.6.2026.11.11.18.40.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Nov 2026 18:40:34 -0800 (PST) From: Hang Zhengyang To: Zhao Gongyi Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, james.clark@linaro.org, x86@kernel.org, kim.phillips@amd.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf/x86: Reject pair-counter groups with no GP budget Date: Thu, 12 Nov 2026 10:40:24 +0800 Message-ID: <20261112024027.3678221-1-hang.zhengyang1010@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109110356.27709-1-zhaogongyi@bytedance.com> References: <20261109110356.27709-1-zhaogongyi@bytedance.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, 09 Nov 2026 19:03:56 +0800, Zhao Gongyi wrote: > AMD large-increment events reserve an extra GP counter. A syzkaller > reproducer opens a perf event group until the adjusted GP budget is > exhausted. x86_schedule_events() then WARNs on the unschedulable group. Tested on AMD Zen 3 (KVM guest, tip perf/urgent): a group of six fp_ret_sse_avx_ops.all events hits the WARN without this patch and not with it; smaller groups still schedule. Without your n_pair fix the WARN fires only once per CPU. Tested-by: Hang Zhengyang