kvm_vgic_set_owner() leaks a reference on the vgic_irq descriptor, which does not seem to match up with any vgic_put_irq() that I can find. Since the irq pointer is not passed out and the caller must anyway subsequently use vgic_get_irq() when is wants a pointer, it is not clear why we should have a dangling refcount here. The refcount is still needed inside kvm_vgic_set_owner() to prevent the vgic_irq struct from disappearing while while it is manipulated. So, keep it vgic_get_irq() here, but add the matching vgic_put_irq() before returning. unreferenced object 0xffff800b6365ab80 (size 128): comm "qemu-system-aar", pid 14414, jiffies 4300822606 (age 84.436s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 b0 e1 e0 38 00 00 ff ff ...........8.... b0 e1 e0 38 00 00 ff ff 78 e6 ad dd 0a 80 ff ff ...8....x....... backtrace: [<00000000a08b80e2>] kmem_cache_alloc+0x178/0x208 [<00000000114591cb>] vgic_add_lpi.part.5+0x34/0x190 [<00000000ec1425ae>] vgic_its_cmd_handle_mapi+0x320/0x348 [<00000000935c5c32>] vgic_its_process_commands.part.14+0x350/0x8b8 [<00000000dc256d2c>] vgic_mmio_write_its_cwriter+0x78/0x98 [<000000008659acd2>] dispatch_mmio_write+0xd4/0x120 [...] Cc: Christoffer Dall <christoffer.dall@xxxxxxx> Fixes: c6ccd30e0de3 ("KVM: arm/arm64: Introduce an allocator for in-kernel irq lines") Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> --- Based on the limited testing I've done so far, the patch _appears_ to fix the bug. However, I still don't understand which the bug is intermittent, or why the arch_timer or pmu (the only apparent users of kvm_vgic_set_owner()) are claiming an LPI in the first place. So there may be other bugs in the mix, or I may have misunderstood something... The bug (and fix) were observed with native qemu on ThunderX2, on a merge of v5.1 with kvmarm/next commit 9eecfc22e0bf ("KVM: arm64: Fix ptrauth ID register masking logic"). My qemu invocation was: $ qemu-system-aarch64 -machine virt,accel=kvm,gic_version=3 -cpu host \ -smp 4 -nographic \ -drive id=vblock,file=block.qcow2,format=qcow2,if=none \ -device virtio-blk-device,drive=vblock \ -kernel Image -append 'root=/dev/vda1 ro' --- virt/kvm/arm/vgic/vgic.c | 1 + 1 file changed, 1 insertion(+) diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c index 191decc..930319c 100644 --- a/virt/kvm/arm/vgic/vgic.c +++ b/virt/kvm/arm/vgic/vgic.c @@ -599,6 +599,7 @@ int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner) else irq->owner = owner; raw_spin_unlock_irqrestore(&irq->irq_lock, flags); + vgic_put_irq(vcpu->kvm, irq); return ret; } -- 2.1.4 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm