From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f174.google.com (mail-qk1-f174.google.com [209.85.222.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0335721CC71 for ; Tue, 11 Aug 2026 15:24:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786461880; cv=none; b=t7Mi0w7A+GzrLQMvrT2QmQoK09sCHk6sYH0fnPOcX49HVj/50YBaB6M+U3+YmAYmoaRtaWbjKMHz5UR+VrKVsx/KjwDL1HiKkA9CNOAvYP+x6PCTtYT2SKt2xGFcCh0kYiPSvKV2h84xIxKtawQQ8hnpkgpr4JeXO0Jgs0F6Nk8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786461880; c=relaxed/simple; bh=UlhJrx4cD0iyVN15M9xGt+ngtuV5yPj/OQO+zrMn8bw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Y9g+A4YlsMP4L7FjsLzpqq5UVksg7z1hjn0/LcUHj8jmslib0OijJQec/0BBXp7jhJXy+++2KgkGbDfVeCOE19qdTdquj5mTLOmhkdR1AtLnO8A0vKmkRIDOg0FECIHg6C645B88P5jrP5wbGKmrmIgIxzz090q8fEedSQa97P4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=oZDgJ02r; arc=none smtp.client-ip=209.85.222.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="oZDgJ02r" Received: by mail-qk1-f174.google.com with SMTP id af79cd13be357-9349ad9c857so5090185a.1 for ; Tue, 11 Aug 2026 08:24:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1786461878; x=1787066678; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=GJpznJoS0l7uzYWTFF1MoJR9UykE3LUYDEr5DpChX2M=; b=oZDgJ02rM9PMe9yWrEcGQOxGZCOoAkL0AZza0UjpTSUIJhslwZh5j96tq0wJIH73je sbQFWOzrQn5+m52b8mYtNWuvsFhthip6ZqHwvWRCQKRr4WNjbJNGdkaswQvmhTfBQdJ+ 9ajORS9BbnLCYOJlmx1IJEPH7UxVNTD2Lxedj9JNNLcGs0KJUw64MzO0Q8DfYo41b7u9 DPuhGQ6blutenuWqroAAsm5XJaR36stVkyijtYG8m4kiTVi64XAcrBe9DT6dsx8O+Oux 2Qr9hXw3IjGg0/6uwgh91FGeqyiXiXnqsuSLtNSsL/0q7kS0I6kwlGykEp/IA21WV96e Z7Og== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786461878; x=1787066678; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=GJpznJoS0l7uzYWTFF1MoJR9UykE3LUYDEr5DpChX2M=; b=Ix1l5igAAkRUkVWbZMnLJNzqCetKh3bz5bqI+9pS/y+9CNRp8N4RTuv5/RQ3cOXrl7 R1oi6w4maPXhDXTqlIBaOMLeEU4+MF3mJMyn4LupFSiNOD8bX4SaVZvsDIDBn67XHx7r PMGNg053w4sjW2D3uxSZ+NH4/FrC30z2wXca7aIwggujgKVr1qEYVs+k5q9YLHmpjbZR Z5EwVz3TB8xe012bQEC7F01lMek+wE2QfYETTIvfIsDEWdgpu4fpKw5J9UoKRkWkyBSz nTgK68vaQastiPrHdDH8swy2LdwbqbuF14JshH7+G9TJ3xhIQwW34dU4XtIyuqzAvnrZ oRAg== X-Forwarded-Encrypted: i=1; AHgh+RqDx3W0QqUFawMOEouq5TOSIeTc8iRMezD5bxVGzsvbUg0XX2UsSvXL39b7Yw5rH89gl6U=@vger.kernel.org X-Gm-Message-State: AOJu0YzYYho2AtUfQTK3nkCqtauhWyxdXrUd95vxZyI8cjA/0Lzjxcy0 dOapf4lukcOjMNuRmEA7J79QrMEJDEmSC8e3jB150/kvGrZkTm0hSyADLJKhABIfeXAzCOSH9ZA cNmQr X-Gm-Gg: AR+sD13MK6Fd2dDxA8hACVoovwOAX3PQ3MDoM8xcVNX2ajiCWj/daJ8vOpo71F7Kbdw 6mgwOLRGNm6gpNDV+ao5HDy7nNldmvSFwJL4z2WzL0rv1tFlV7iq9VWrLhXZ7EIO6NSpQdRNrGi 3Cwg1MR9lITEQ1nB8ZVyOgn1C1OPnhXT/lvruq1eDdvSRwrsiGCxYg9ibUTjf3qb3FMVnq9Yae+ 3R7lPLgoK/KdL+NeL+q4P20lTsjmhSG5rqrIlhRr4Au5C7zp3XO1phiWhD3hybR65fsDPUMU1Xz MNfxUABUIIsN0m0+bQC1ExtfsiI1in9SxdQMa0nk4X4y27rL3De1gMYmCH5a7zV0A/RW0uWDFqZ /Ow16GOzaFQeTJax8LQ0SpfJC926++dA4cSTwnEKofljGTMXJhvR2dhWGyOcNb/9tN7sfIwDzBX AMxhhBafZo8ruQI9VeMY2H/Dvmbb1KU20EafhDZw== X-Received: by 2002:a05:620a:c50:b0:936:48f2:b04f with SMTP id af79cd13be357-936a8e5f5ecmr330842085a.6.1786461877528; Tue, 11 Aug 2026 08:24:37 -0700 (PDT) Received: from ziepe.ca ([142.166.156.215]) by smtp.gmail.com with ESMTPSA id af79cd13be357-936a8472ed4sm132935485a.9.2026.08.11.08.24.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Aug 2026 08:24:36 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wtoLD-00000002WyE-1V0l; Tue, 11 Aug 2026 12:24:35 -0300 Date: Tue, 11 Aug 2026 12:24:35 -0300 From: Jason Gunthorpe To: David Woodhouse Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. 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: kvm@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