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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Sebastian Andrzej Siewior , Clark Williams , Simona Vetter , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Christian =?utf-8?B?S8O2bmln?= , "Paul E. McKenney" , Sean Christopherson , Paolo Bonzini , linux-mm@kvack.org, kvm@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mmu_notifier: Remove non_block_start/end() from notifier invocation Message-ID: <20260812134934.GC662699@ziepe.ca> References: <20260811135537.GC544626@ziepe.ca> <1d669aca4ffee797b9c29215382444a5b23624b3.camel@infradead.org> <20260811142730.GG544626@ziepe.ca> <20260811104229.72fdd928@gandalf.local.home> <37b83b429b9f14ea6ad4ca1c13cc8e565ec09033.camel@infradead.org> <44c51ace9b0dc44b795f6f48c91cda440eed910b.camel@infradead.org> <20260812122759.GA662699@ziepe.ca> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Aug 12, 2026 at 02:46:08PM +0100, David Woodhouse wrote: > I hear you. I'm less sceptical, given the use case, but I'll certainly > concede that the universe is known for inventing better idiots. > > I'm certainly not averse to having a wrapper so that the read sections > don't just srcu_read_lock() directly, but also get a sanity check > (non_block_start? local_irq_save? what would it actually be? does it > have to be different for the hardirq vs. process-context invocations?) > for free. > > Or instead of a GPC-specific wrapper, do we make it a first-class SRCU > citizen, SRCU_READ_FLAVOR_ATOMIC? If it disables preemption, we'd know > that lock+unlock must happen on the *same* CPU, which could potentially > simplify my new try_synchronize_srcu() and/or allow for a *spinning* > grace period if we really do want that (although I'm unconvinced; it's > *latency* we care about here, and punting to the WQ when we *already* > have to wait is fair enough). These all seem like good ideas, then you don't need to touch the notifiers.. Jason