linux-kernel - Re: [PATCH] Revert "KVM: doc: Document the life cycle of a VM and its resources"

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Date:   Tue, 30 Apr 2019 21:31:12 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Radim Krčmář <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Cornelia Huck <cohuck@...hat.com>
Subject: Re: [PATCH] Revert "KVM: doc: Document the life cycle of a VM and its
 resources"

On 29/04/19 15:25, Radim Krčmář wrote:
> This reverts commit 919f6cd8bb2fe7151f8aecebc3b3d1ca2567396e.
> 
> The patch was applied twice.
> The first commit is eca6be566d47029f945a5f8e1c94d374e31df2ca.
> 
> Reported-by: Cornelia Huck <cohuck@...hat.com>
> Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
> ---
>  Documentation/virtual/kvm/api.txt | 17 -----------------
>  1 file changed, 17 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index b62ad0d94234..26dc1280b49b 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -69,23 +69,6 @@ by and on behalf of the VM's process may not be freed/unaccounted when
>  the VM is shut down.
>  
>  
> -It is important to note that althought VM ioctls may only be issued from
> -the process that created the VM, a VM's lifecycle is associated with its
> -file descriptor, not its creator (process).  In other words, the VM and
> -its resources, *including the associated address space*, are not freed
> -until the last reference to the VM's file descriptor has been released.
> -For example, if fork() is issued after ioctl(KVM_CREATE_VM), the VM will
> -not be freed until both the parent (original) process and its child have
> -put their references to the VM's file descriptor.
> -
> -Because a VM's resources are not freed until the last reference to its
> -file descriptor is released, creating additional references to a VM via
> -via fork(), dup(), etc... without careful consideration is strongly
> -discouraged and may have unwanted side effects, e.g. memory allocated
> -by and on behalf of the VM's process may not be freed/unaccounted when
> -the VM is shut down.
> -
> -
>  3. Extensions
>  -------------
>  
> 

Applied, thanks.

Paolo