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Message-ID: <20190211185318.GA13953@cmpxchg.org> References: <20190211095724.nmflaigqlcipbxtk@linutronix.de> <20190211113829.sqf6bdi4c4cdd3rp@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190211113829.sqf6bdi4c4cdd3rp@linutronix.de> User-Agent: Mutt/1.11.2 (2019-01-07) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Feb 11, 2019 at 12:38:29PM +0100, Sebastian Andrzej Siewior wrote: > Commit > > 68d48e6a2df57 ("mm: workingset: add vmstat counter for shadow nodes") > > introduced an IRQ-off check to ensure that a lock is held which also > disabled interrupts. This does not work the same way on -RT because none > of the locks, that are held, disable interrupts. > Replace this check with a lockdep assert which ensures that the lock is > held. > > Cc: Peter Zijlstra > Signed-off-by: Sebastian Andrzej Siewior I'm not against checking for the lock, but if IRQs aren't disabled, what ensures __mod_lruvec_state() is safe? I'm guessing it's because preemption is disabled and irq handlers are punted to process context. That said, it seems weird to me that spin_lock_irqsave(); BUG_ON(!irqs_disabled()); spin_unlock_irqrestore(); would trigger. Wouldn't it make sense to have a raw_irqs_disabled() or something and keep the irqs_disabled() abstraction layer intact?