Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <56b9d000-8743-52cb-4f10-4d3fa2b30f29@redhat.com>
Date:   Mon, 6 Dec 2021 07:55:18 +0100
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Subject: Re: [KVM] d3750a0923:
 WARNING:possible_circular_locking_dependency_detected
Content-Language: en-US
To:     kernel test robot <oliver.sang@intel.com>,
        David Matlack <dmatlack@google.com>
Cc:     0day robot <lkp@intel.com>, LKML <linux-kernel@vger.kernel.org>,
        lkp@lists.01.org, kvm@vger.kernel.org,
        Ben Gardon <bgardon@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jim Mattson <jmattson@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Janis Schoetterl-Glausch <scgl@linux.vnet.ibm.com>,
        Junaid Shahid <junaids@google.com>,
        Oliver Upton <oupton@google.com>,
        Harish Barathvajasankar <hbarath@google.com>,
        Peter Xu <peterx@redhat.com>, Peter Shier <pshier@google.com>
References: <20211205133039.GD33002@xsang-OptiPlex-9020>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <20211205133039.GD33002@xsang-OptiPlex-9020>
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Precedence: bulk

On 12/5/21 14:30, kernel test robot wrote:
>
> Chain exists of:
>   fs_reclaim --> mmu_notifier_invalidate_range_start --> &(kvm)->mmu_lock
>
>  Possible unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock(&(kvm)->mmu_lock);
>                                lock(mmu_notifier_invalidate_range_start);
>                                lock(&(kvm)->mmu_lock);
>   lock(fs_reclaim);
>

David, this is yours; basically, kvm_mmu_topup_memory_cache must be 
called outside the mmu_lock.

Paolo