From: Heyi Guo <[email protected]> commit d4a8061a7c5f7c27a2dc002ee4cb89b3e6637e44 upstream.
If the ap_list is longer than 256 entries, merge_final() in list_sort() will call the comparison callback with the same element twice, causing a deadlock in vgic_irq_cmp(). Fix it by returning early when irqa == irqb. Cc: [email protected] # 4.7+ Fixes: 8e4447457965 ("KVM: arm/arm64: vgic-new: Add IRQ sorting") Signed-off-by: Zenghui Yu <[email protected]> Signed-off-by: Heyi Guo <[email protected]> [maz: massaged commit log and patch, added Fixes and Cc-stable] Signed-off-by: Marc Zyngier <[email protected]> Signed-off-by: Will Deacon <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- virt/kvm/arm/vgic/vgic.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/virt/kvm/arm/vgic/vgic.c +++ b/virt/kvm/arm/vgic/vgic.c @@ -254,6 +254,13 @@ static int vgic_irq_cmp(void *priv, stru bool penda, pendb; int ret; + /* + * list_sort may call this function with the same element when + * the list is fairly long. + */ + if (unlikely(irqa == irqb)) + return 0; + raw_spin_lock(&irqa->irq_lock); raw_spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
