kvm: arm64: stable commit "Fix kernel BUG() due to bad backport of FPSIMD/SVE/SME fix" deadlocks host kernel
Commits 8f4dc4e54eed4 (6.1.y) and 23249dade24e6 (5.15.y) (maybe other stable kernels as well) deadlock the host kernel (presumably a recursive spinlock):
queued_spin_lock_slowpath+0x274/0x358 raw_spin_rq_lock_nested+0x2c/0x48 _raw_spin_rq_lock_irqsave+0x30/0x4c run_rebalance_domains+0x808/0x2e18 __do_softirq+0x104/0x550 irq_exit+0x88/0xe0 handle_domain_irq+0x7c/0xb0 gic_handle_irq+0x1cc/0x420 call_on_irq_stack+0x20/0x48 do_interrupt_handler+0x3c/0x50 el1_interrupt+0x30/0x58 el1h_64_irq_handler+0x18/0x24 el1h_64_irq+0x7c/0x80 kvm_arch_vcpu_ioctl_run+0x24c/0x49c kvm_vcpu_ioctl+0xc4/0x614
We found out a similar report at [1], but it doesn't seem like a formal patch was ever posted. Will, can you please send a formal patch so that stable kernels can run VMs again?
[1] https://lists.linaro.org/archives/list/linux-stable-mirror@lists.linaro.org/...
On Wed, Oct 08, 2025 at 01:45:32PM +0900, Sergey Senozhatsky wrote:
Commits 8f4dc4e54eed4 (6.1.y) and 23249dade24e6 (5.15.y) (maybe other stable kernels as well) deadlock the host kernel (presumably a recursive spinlock):
queued_spin_lock_slowpath+0x274/0x358 raw_spin_rq_lock_nested+0x2c/0x48 _raw_spin_rq_lock_irqsave+0x30/0x4c run_rebalance_domains+0x808/0x2e18 __do_softirq+0x104/0x550 irq_exit+0x88/0xe0 handle_domain_irq+0x7c/0xb0 gic_handle_irq+0x1cc/0x420 call_on_irq_stack+0x20/0x48 do_interrupt_handler+0x3c/0x50 el1_interrupt+0x30/0x58 el1h_64_irq_handler+0x18/0x24 el1h_64_irq+0x7c/0x80 kvm_arch_vcpu_ioctl_run+0x24c/0x49c kvm_vcpu_ioctl+0xc4/0x614
We found out a similar report at [1], but it doesn't seem like a formal patch was ever posted. Will, can you please send a formal patch so that stable kernels can run VMs again?
Yup, already queued up for stable:
https://lore.kernel.org/r/20251003183917.4209-1-will@kernel.org https://lore.kernel.org/r/20251003184018.4264-1-will@kernel.org https://lore.kernel.org/r/20251003184054.4286-1-will@kernel.org
Sorry for the breakage.
Will
On (25/10/08 09:45), Will Deacon wrote: [..]
We found out a similar report at [1], but it doesn't seem like a formal patch was ever posted. Will, can you please send a formal patch so that stable kernels can run VMs again?
Yup, already queued up for stable:
https://lore.kernel.org/r/20251003183917.4209-1-will@kernel.org https://lore.kernel.org/r/20251003184018.4264-1-will@kernel.org https://lore.kernel.org/r/20251003184054.4286-1-will@kernel.org
Splendid!
Sorry for the breakage.
No worries!
linux-stable-mirror@lists.linaro.org
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Sergey Senozhatsky -
Will Deacon