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[118.167.223.132]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-81e46339579sm2551196b3a.18.2026.01.09.11.45.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jan 2026 11:45:38 -0800 (PST) Message-ID: <69615ae2.050a0220.47ba6.c4aa@mx.google.com> X-Google-Original-Message-ID: Date: Sat, 10 Jan 2026 03:45:36 +0800 From: JiaHong Su To: Paolo Bonzini , Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [BUG] KVM: hung task during vCPU destruction in kvm_clear_async_pf_completion_queue() Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello, I found the following issue using Syzkaller on: HEAD commit: 9ace475 Linux 6.19-rc4 Kernel config: https://gist.github.com/AxelHowe/7fb5b3917d2f4a18c1d8cefbfd5846ef A hung task warning is reported during KVM vCPU destruction. INFO: task repro:9778 blocked for more than 143 seconds. Not tainted 6.19.0-rc4 #8 Blocked by coredump. Call Trace: __schedule schedule schedule_timeout __wait_for_common __flush_work cancel_work_sync kvm_clear_async_pf_completion_queue kvm_arch_vcpu_destroy kvm_destroy_vcpus kvm_arch_destroy_vm kvm_put_kvm kvm_vcpu_release __fput task_work_run do_exit do_group_exit get_signal arch_do_signal_or_restart entry_SYSCALL_64_after_hwframe The teardown path blocks in cancel_work_sync() while clearing the async page fault completion queue. The wait exceeds the hung task timeout and does not appear to make forward progress in this exit/coredump context. C reproducer, full dmesg output are available at: https://gist.github.com/AxelHowe/f09bce07178d13a2ee095f30eef8327e Thanks, JiaHong Su