From: Keith Busch <kbusch@kernel.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking
Date: Mon, 27 Jan 2025 10:04:58 -0700 [thread overview]
Message-ID: <Z5e8umkPeRri0Z_p@kbusch-mbp> (raw)
In-Reply-To: <Z5e4w7IlEEk2cpH-@google.com>
On Mon, Jan 27, 2025 at 08:48:03AM -0800, Sean Christopherson wrote:
> If vhost_task_create() fails, then the call_once() will "succeed" and mark the
> structure as ONCE_COMPLETED. The first KVM_RUN will fail with -ENOMEM, but any
> subsequent calls will succeed, including in-flight KVM_RUNs on other threads.
The criteria for returning -ENOMEM for any KVM_RUN is if we have a NULL
nx_huge_page_recovery_thread vhost_task. So I think that part, at least,
is fine.
The call_once is just needed to ensure that only the very first KVM_RUN
even tries to create it. If the vhost_task_create fails, then all the
KVM_RUN threads will see the NULL nx_huge_page_recovery_thread and
return -ENOMEM.
What you're suggesting here will allow a subsequent thread to attempt
creating the vhost task if the first one failed. Maybe you do want to
try again, but the current upstream code doesn't retry this, so I
thought it best to keep that behavior.
next prev parent reply other threads:[~2025-01-27 17:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-24 23:46 [PATCH] KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking Sean Christopherson
2025-01-25 0:50 ` Sean Christopherson
2025-01-25 4:11 ` Keith Busch
2025-01-27 16:48 ` Sean Christopherson
2025-01-27 17:04 ` Keith Busch [this message]
2025-01-27 17:19 ` Sean Christopherson
2025-01-27 18:22 ` Keith Busch
2025-01-28 15:41 ` Paolo Bonzini
2025-01-28 15:44 ` Keith Busch
2025-02-04 16:28 ` Paolo Bonzini
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