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[2a02:3100:ac88:a501:9c5c:9666:3a00:3cdb]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-480020be8f3sm24111242f8f.0.2026.08.09.11.11.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Aug 2026 11:11:55 -0700 (PDT) Date: Sun, 9 Aug 2026 20:11:54 +0200 From: Karl Mehltretter To: Marc Zyngier Cc: Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 1/2] KVM: arm64: nv: Allocate the shadow S2 MMUs individually Message-ID: References: <20260803224405.41468-1-kmehltretter@gmail.com> <86mrv2arf2.wl-maz@kernel.org> <878q6fplpd.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: stable@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: <878q6fplpd.wl-maz@kernel.org> On Sun, Aug 09, 2026 at 12:39:10PM +0100, Marc Zyngier wrote: > My current patch is as follows, and so far, I haven't seen much that I > like better. > Hi Marc, Thanks for your revised patch. I think one correctness issue is in there. > + for (i = 0; !ret && i < S2_MMU_PER_VCPU; i++) > + ret = init_nested_s2_mmu(kvm, &tmp[i]); > + if (ret) { > + while (--i >= 0) > + kvm_free_stage2_pgd(&tmp[i]); The increment expression of the for loop still runs after an error. I reproduced this with failslab. If init_nested_s2_mmu() fails while allocating pgt, before mmu->arch is assigned, the for loop still increments i. Thus while (--i >= 0) passes the failed entry to kvm_free_stage2_pgd(). The resulting log is: Unable to handle kernel paging request at virtual address fffffffffffff650 Internal error: Oops: 0000000096000046 [#1] SMP Call trace: _raw_write_lock kvm_free_stage2_pgd kvm_vcpu_init_nested Thanks, Karl