Re: [PATCH kernel] KVM: PPC: Book3S HV: Make unique debugfs nodename
From: Alexey Kardashevskiy <hidden>
Date: 2021-08-13 09:50:12
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On 07/07/2021 14:13, Alexey Kardashevskiy wrote:
Currently it is vm-$currentpid which works as long as there is just one VM per the userspace (99.99% cases) but produces a bunch of "debugfs: Directory 'vm16679' with parent 'kvm' already present!" when syzkaller (syscall fuzzer) is running so only one VM is present in the debugfs for a given process. This changes the debugfs node to include the LPID which alone should be system wide unique. This leaves the existing pid for the convenience of matching the VM's debugfs with the running userspace process (QEMU). Signed-off-by: Alexey Kardashevskiy <redacted>
Looks like this is not enough as syzkaller still manages to cause the error message, I need more robust approach as in https://lore.kernel.org/patchwork/patch/1472025/ or alternatively move this debugfs stuff under the platform-independent directory, how about that?
quoted hunk ↗ jump to hunk
--- arch/powerpc/kvm/book3s_hv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 1d1fcc290fca..0223ddc0eed0 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c@@ -5227,7 +5227,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm) /* * Create a debugfs directory for the VM */ - snprintf(buf, sizeof(buf), "vm%d", current->pid); + snprintf(buf, sizeof(buf), "vm%d-lp%ld", current->pid, lpid); kvm->arch.debugfs_dir = debugfs_create_dir(buf, kvm_debugfs_dir); kvmppc_mmu_debugfs_init(kvm); if (radix_enabled())
-- Alexey