I had tried to retest with your patch,and I think the memory leak was resolved by it. Thanks! -----邮件原件----- 发件人: Sean Christopherson [mailto:seanjc@xxxxxxxxxx] 发送时间: 2022年12月16日 2:17 收件人: 柳菁峰 <liujingfeng@xxxxxxxxxxx> 抄送: linux-kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx; syzkaller@xxxxxxxxxxxxxxxx 主题: Re: Found a memory leak in kvm module On Mon, Dec 12, 2022, 柳菁峰 wrote: > Hello,I have found a memory leak bug in kvm module by syzkaller.It was > found in linux-5.4 but it also could be reproduced in the latest linux version. Ah, I assume by "linux-5.4" you mean "stable v5.4.x kernels that contain commit 7d1bc32d6477 ("KVM: Stop looking for coalesced MMIO zones if the bus is destroyed")", because without that fix I can't see any bug that would affect both 5.4 and the upstream kernel. If my assumption is correct, then I'm 99% certain the issue is that the target device isn't destroyed if allocating the new bus fails. I haven't had luck with the automatic fault injection, but was able to confirm a leak with this hack. diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 13e88297f999..22d9ab1b5c25 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -5424,7 +5424,7 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, struct kvm_io_device *dev) { int i, j; - struct kvm_io_bus *new_bus, *bus; + struct kvm_io_bus *new_bus = NULL, *bus; lockdep_assert_held(&kvm->slots_lock); @@ -5441,6 +5441,7 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, if (i == bus->dev_count) return 0; + if (!IS_ENABLED(CONFIG_X86_64)) new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1), GFP_KERNEL_ACCOUNT); if (new_bus) { The fix is to destroy the target device before bailing. I'll send a proper patch either way, but it would be nice to get confirmation that this is the same bug that you hit with "linux-5.4". Thanks! --- virt/kvm/coalesced_mmio.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c index 0be80c213f7f..5ef88f5a0864 100644 --- a/virt/kvm/coalesced_mmio.c +++ b/virt/kvm/coalesced_mmio.c @@ -187,15 +187,17 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, r = kvm_io_bus_unregister_dev(kvm, zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev); + kvm_iodevice_destructor(&dev->dev); + /* * On failure, unregister destroys all devices on the * bus _except_ the target device, i.e. coalesced_zones - * has been modified. No need to restart the walk as - * there aren't any zones left. + * has been modified. Bail after destroying the target + * device, there's no need to restart the walk as there + * aren't any zones left. */ if (r) break; - kvm_iodevice_destructor(&dev->dev); } } base-commit: 0f30b25edea48433eb32448990557364436818e6 --
