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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , 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: <20260811152435.GH544626@ziepe.ca> References: <20260811135537.GC544626@ziepe.ca> <1d669aca4ffee797b9c29215382444a5b23624b3.camel@infradead.org> <20260811142730.GG544626@ziepe.ca> <15a7bd252a9aaeefe393f5609ec383ce2c61694a.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=us-ascii Content-Disposition: inline In-Reply-To: <15a7bd252a9aaeefe393f5609ec383ce2c61694a.camel@infradead.org> On Tue, Aug 11, 2026 at 04:15:36PM +0100, David Woodhouse wrote: > On Tue, 2026-08-11 at 11:27 -0300, Jason Gunthorpe wrote: > > > > The unstated secondary purprose of the atomic context is to force the > > driver implementors to make sane choices that don't degrade the MM > > spectacularly. > > You realise it only does this is in the OOM handler context when the > normal death of the process takes too long, and I literally had to hack > the kernel to even get the splat to trigger in the first place, right? > > I don't think it's keeping your driver authors honest... :) It is documented to be like this, even if it is hard to test.. Even for normal blocking notifiers you should not be using synchronize_rcu(). Jason