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[209.85.218.43]) by smtp.gmail.com with ESMTPSA id ok21sm2186820ejb.96.2020.10.29.16.18.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Oct 2020 16:18:23 -0700 (PDT) Received: by mail-ej1-f43.google.com with SMTP id s15so6088349ejf.8 for ; Thu, 29 Oct 2020 16:18:23 -0700 (PDT) X-Received: by 2002:a2e:8815:: with SMTP id x21mr3018764ljh.312.1604013088281; Thu, 29 Oct 2020 16:11:28 -0700 (PDT) MIME-Version: 1.0 References: <20201029221806.189523375@linutronix.de> In-Reply-To: <20201029221806.189523375@linutronix.de> From: Linus Torvalds Date: Thu, 29 Oct 2020 16:11:12 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch V2 00/18] mm/highmem: Preemptible variant of kmap_atomic & friends To: Thomas Gleixner Cc: LKML , linux-arch , Peter Zijlstra , Paul McKenney , David Airlie , Daniel Vetter , Ard Biesheuvel , Herbert Xu , Christoph Hellwig , Sebastian Andrzej Siewior , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Andrew Morton , Linux-MM , "the arch/x86 maintainers" , Vineet Gupta , "open list:SYNOPSYS ARC ARCHITECTURE" , Russell King , Arnd Bergmann , Linux ARM , Guo Ren , linux-csky@vger.kernel.org, Michal Simek , Thomas Bogendoerfer , linux-mips@vger.kernel.org, Nick Hu , Greentime Hu , Vincent Chen , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev , "David S. Miller" , linux-sparc , Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org Content-Type: text/plain; charset="UTF-8" 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 Thu, Oct 29, 2020 at 3:32 PM Thomas Gleixner wrote: > > > Though I wanted to share the current state of affairs before investigating > that further. If there is consensus in going forward with this, I'll have a > deeper look into this issue. Me likee. I think this looks like the right thing to do. I didn't actually apply the patches, but just from reading them it _looks_ to me like you do the migrate_disable() unconditionally, even if it's not a highmem page.. That sounds like it might be a good thing for debugging, but not necessarily great in general. Or am I misreading things? Linus