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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , 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: <20260811153032.GJ544626@ziepe.ca> References: <20260811135537.GC544626@ziepe.ca> <1d669aca4ffee797b9c29215382444a5b23624b3.camel@infradead.org> <20260811142730.GG544626@ziepe.ca> <20260811104229.72fdd928@gandalf.local.home> <37b83b429b9f14ea6ad4ca1c13cc8e565ec09033.camel@infradead.org> 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-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <37b83b429b9f14ea6ad4ca1c13cc8e565ec09033.camel@infradead.org> On Tue, Aug 11, 2026 at 04:24:48PM +0100, David Woodhouse wrote: > I had a second reason for disabling the overzealous check too: to allow > SRCU grace periods within the notifier callbacks. Don't agree with allowing this at all. > > Thus, perhaps something like this: > > > >   if (ops->invalidate_range_start) { > >   int _ret; > >   > > if (!IS_ENABLED(CONFIG_PREEMPT_RT) && !mmu_notifier_range_blockable(range)) > > non_block_start(); > >   _ret = ops->invalidate_range_start(subscription, range); > > if (!IS_ENABLED(CONFIG_PREEMPT_RT) && !mmu_notifier_range_blockable(range)) > > non_block_end(); > > > > ? This seems fine to me > Or put it in a per-mmu-notifier-ops flag (a bit like the one in commit > 5ff7091f5a2c, but with almost opposite semantics), and let the drivers > Jason cares about still keep the guard, while KVM doesn't need to. With > or without the RT part... Nope, common API semantics please. Jason