linux-kernel - Re: [PATCH] KVM: X86: Fix x86

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Message-ID: <2ea05111-1598-f82c-e868-0615bc003612@redhat.com>
Date:   Fri, 11 Jun 2021 17:53:58 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, stable@...r.kernel.org
Subject: Re: [PATCH] KVM: X86: Fix x86_emulator slab cache leak

On 11/06/21 06:59, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> Commit c9b8b07cded58 (KVM: x86: Dynamically allocate per-vCPU emulation context)
> tries to allocate per-vCPU emulation context dynamically, however, the
> x86_emulator slab cache is still exiting after the kvm module is unload
> as below after destroying the VM and unloading the kvm module.
> 
> grep x86_emulator /proc/slabinfo
> x86_emulator          36     36   2672   12    8 : tunables    0    0    0 : slabdata      3      3      0
> 
> This patch fixes this slab cache leak by destroying the x86_emulator slab cache
> when the kvm module is unloaded.
> 
> Fixes: c9b8b07cded58 (KVM: x86: Dynamically allocate per-vCPU emulation context)
> Cc: stable@...r.kernel.org
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
>   arch/x86/kvm/x86.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6d3955a6a763..fe26f33e8782 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8258,6 +8258,7 @@ void kvm_arch_exit(void)
>   	kvm_x86_ops.hardware_enable = NULL;
>   	kvm_mmu_module_exit();
>   	free_percpu(user_return_msrs);
> +	kmem_cache_destroy(x86_emulator_cache);
>   	kmem_cache_destroy(x86_fpu_cache);
>   #ifdef CONFIG_KVM_XEN
>   	static_key_deferred_flush(&kvm_xen_enabled);
> 

Queued, thanks

Paolo