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[2a02:3100:ad43:d501:2c28:bb72:120d:420e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1fd0f4427sm90362275e9.3.2026.10.21.22.17.16 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 21 Oct 2026 22:17:18 -0700 (PDT) From: Karl Mehltretter To: Steven Rostedt , Peter Zijlstra , Thomas Gleixner Cc: Karl Mehltretter , Catalin Marinas , Will Deacon , Mark Rutland , Ingo Molnar , Andy Lutomirski , Frederic Weisbecker , "Paul E . McKenney" , Sebastian Andrzej Siewior , Boqun Feng , Waiman Long , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Hongyan Xia , Jonathan Corbet , Shuah Khan , Randy Dunlap , Andrew Morton , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-arm-kernel@lists.infradead.org, linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-doc@vger.kernel.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [RFC PATCH 02/12] lockdep: Use raw access for pinned hardirq state Date: Thu, 22 Oct 2026 07:16:44 +0200 Message-Id: <20261022051654.79224-3-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20261022051654.79224-1-kmehltretter@gmail.com> References: <20261022051654.79224-1-kmehltretter@gmail.com> X-Mailing-List: linux-doc@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 irqentry_nmi_enter() reads lockdep's hardirq state before __nmi_enter() establishes NMI context. Arm64 does the same for its NMI-like EL1 debug entry. Both paths run with interrupts disabled and cannot migrate. lockdep_hardirqs_enabled() uses this_cpu_read(), whose preemption checks are unnecessary for these callers. Add a raw accessor and use it in the two entry paths and in lockdep_hardirqs_off(). Keep the existing accessor for callers which are not already pinned. Check the interrupt state before accessing per-CPU state in lockdep_hardirqs_off(), independently of warning suppression. On arm64, this change does not by itself make the call chain noinstr-safe: __kern_my_cpu_offset() must also be forced inline. That prerequisite is listed in the cover letter. Assisted-by: LLM --- arch/arm64/kernel/entry-common.c | 2 +- include/linux/irqflags.h | 3 +++ kernel/entry/common.c | 2 +- kernel/locking/lockdep.c | 6 ++++-- 4 files changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 72c03ccea59fe..93056a766fb20 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -141,7 +141,7 @@ static noinstr irqentry_state_t arm64_enter_el1_dbg(struct pt_regs *regs) { irqentry_state_t state; - state.lockdep = lockdep_hardirqs_enabled(); + state.lockdep = lockdep_hardirqs_enabled_raw(); lockdep_hardirqs_off(CALLER_ADDR0); ct_nmi_enter(); diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 57b074e0cfbbb..5bc179a88e513 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -52,6 +52,8 @@ extern void trace_hardirqs_off(void); # define lockdep_hardirq_context() (raw_cpu_read(hardirq_context)) # define lockdep_softirq_context(p) ((p)->softirq_context) # define lockdep_hardirqs_enabled() (this_cpu_read(hardirqs_enabled)) +/* The caller must already be pinned to the current CPU. */ +# define lockdep_hardirqs_enabled_raw() (raw_cpu_read(hardirqs_enabled)) # define lockdep_softirqs_enabled(p) ((p)->softirqs_enabled) # define lockdep_hardirq_enter() \ do { \ @@ -113,6 +115,7 @@ do { \ # define lockdep_hardirq_context() 0 # define lockdep_softirq_context(p) 0 # define lockdep_hardirqs_enabled() 0 +# define lockdep_hardirqs_enabled_raw() 0 # define lockdep_softirqs_enabled(p) 0 # define lockdep_hardirq_enter() do { } while (0) # define lockdep_hardirq_threaded() do { } while (0) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index e3d381fd3d251..28399c41ebfb1 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -171,7 +171,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) { irqentry_state_t irq_state; - irq_state.lockdep = lockdep_hardirqs_enabled(); + irq_state.lockdep = lockdep_hardirqs_enabled_raw(); __nmi_enter(); lockdep_hardirqs_off(CALLER_ADDR0); diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index c3dc84a7cef26..01dba8fb32a90 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -4543,10 +4543,12 @@ void noinstr lockdep_hardirqs_off(unsigned long ip) * So we're supposed to get called after you mask local IRQs, but for * some reason the hardware doesn't quite think you did a proper job. */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + if (unlikely(!irqs_disabled())) { + DEBUG_LOCKS_WARN_ON(1); return; + } - if (lockdep_hardirqs_enabled()) { + if (lockdep_hardirqs_enabled_raw()) { struct irqtrace_events *trace = ¤t->irqtrace; /* -- 2.39.5 (Apple Git-154)