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Tue, 06 Aug 2024 09:55:23 +0100 Date: Tue, 06 Aug 2024 09:55:22 +0100 Message-ID: <86ikwe2fph.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: Sean Christopherson , Paolo Bonzini , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens , Fuad Tabba Subject: Re: [PATCH v12 54/84] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock In-Reply-To: References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-55-seanjc@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.3 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, seanjc@google.com, pbonzini@redhat.com, zhaotianrui@loongson.cn, maobibo@loongson.cn, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, dmatlack@google.com, stevensd@chromium.org, tabba@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240806_015528_692118_A88C6324 X-CRM114-Status: GOOD ( 15.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 06 Aug 2024 00:26:54 +0100, Oliver Upton wrote: > > On Mon, Aug 05, 2024 at 11:26:03PM +0000, Oliver Upton wrote: > > [+cc Fuad] > > Take 2! > > > Fuad, you mentioned in commit 9c30fc615daa ("KVM: arm64: Move setting > > the page as dirty out of the critical section") that restructuring > > around the MMU lock was helpful for reuse (presumably for pKVM), but I > > lack the context there. > > > > On Fri, Jul 26, 2024 at 04:52:03PM -0700, Sean Christopherson wrote: > > > Mark pages/folios accessed+dirty prior to dropping mmu_lock, as marking a > > > page/folio dirty after it has been written back can make some filesystems > > > unhappy (backing KVM guests will such filesystem files is uncommon, and > > > > typo: s/will/with/ > > > > > the race is minuscule, hence the lack of complaints). See the link below > > > for details. Should we consider reverting 9c30fc615daa then? Thanks, M. -- Without deviation from the norm, progress is not possible.