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Mon, 18 May 2026 16:56:43 -0700 (PDT) Received: from s7t7-debian-test.local ([67.170.89.46]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30294500726sm14141408eec.10.2026.05.18.16.56.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2026 16:56:43 -0700 (PDT) From: Tony Rodriguez To: davem@davemloft.net, sparclinux@vger.kernel.org Cc: linux-kernel@vger.kernel.org, andreas@gaisler.com, tglx@kernel.org, thomas.weissschuh@linutronix.de, regressions@lists.linux.dev, glaubitz@physik.fu-berlin.de, linux@leemhuis.info, torvalds@linux-foundation.org, Tony Rodriguez Subject: [PATCH 0/1] sparc64: Fix tick/stick comparator equal-compare hazard Date: Mon, 18 May 2026 16:56:02 -0700 Message-ID: <20260518235632.5122-1-unixpro1970@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sparc64: avoid missed timer interrupts when comparator equals counter This patch fixes an equal‑compare hazard in the SPARC64 tick/stick comparator logic that can cause missed timer interrupts and stalled hrtimers. Full dmesg and crash dumps: https://github.com/unixpro1970/Sparc64-Kernel-Debugging-Dumps/blob/main/s7-2-05122026-dump.tar.gz Debugging discussion: https://lore.kernel.org/all/87tssb6olo.ffs@tglx/ https://lore.kernel.org/all/871pfcznw0.ffs@tglx/ Short dmesg excerpt: [ 48.632215] rcu: INFO: rcu_sched detected stalls on CPUs/tasks: [ 48.676018] rcu: rcu_sched kthread timer wakeup didn't happen for 5259 jiffies! [ 48.743621] rcu: Possible timer handling issue on cpu=100 timer-softirq=15 Test summary: After applying this patch, S7-2 and T7-1 systems no longer hang on v7 and v7.1 kernels. Tony Rodriguez (1): sparc64: Fix tick/stick comparator equal-compare hazard arch/sparc/kernel/time_64.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 2.53.0