2.6.31-stable review patch. If anyone has any objections, please let us know. ------------------ From: Darrick J. Wong commit: 0ea4ed8e948c30f88c824c973ee4b9529015fe65 upstream I'm seeing an oops condition when kvm-intel and kvm-amd are modprobe'd during boot (say on an Intel system) and then rmmod'd: # modprobe kvm-intel kvm_init() kvm_init_debug() kvm_arch_init() <-- stores debugfs dentries internally (success, etc) # modprobe kvm-amd kvm_init() kvm_init_debug() <-- second initialization clobbers kvm's internal pointers to dentries kvm_arch_init() kvm_exit_debug() <-- and frees them # rmmod kvm-intel kvm_exit() kvm_exit_debug() <-- double free of debugfs files! *BOOM* If execution gets to the end of kvm_init(), then the calling module has been established as the kvm provider. Move the debugfs initialization to the end of the function, and remove the now-unnecessary call to kvm_exit_debug() from the error path. That way we avoid trampling on the debugfs entries and freeing them twice. Signed-off-by: Darrick J. Wong Signed-off-by: Marcelo Tosatti Signed-off-by: Greg Kroah-Hartman --- virt/kvm/kvm_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2590,8 +2590,6 @@ int kvm_init(void *opaque, unsigned int int r; int cpu; - kvm_init_debug(); - r = kvm_arch_init(opaque); if (r) goto out_fail; @@ -2658,6 +2656,8 @@ int kvm_init(void *opaque, unsigned int kvm_preempt_ops.sched_in = kvm_sched_in; kvm_preempt_ops.sched_out = kvm_sched_out; + kvm_init_debug(); + return 0; out_free: @@ -2679,7 +2679,6 @@ out_free_0: __free_page(bad_page); out: kvm_arch_exit(); - kvm_exit_debug(); out_fail: return r; } @@ -2688,6 +2687,7 @@ EXPORT_SYMBOL_GPL(kvm_init); void kvm_exit(void) { kvm_trace_cleanup(); + kvm_exit_debug(); misc_deregister(&kvm_dev); kmem_cache_destroy(kvm_vcpu_cache); sysdev_unregister(&kvm_sysdev); @@ -2697,7 +2697,6 @@ void kvm_exit(void) on_each_cpu(hardware_disable, NULL, 1); kvm_arch_hardware_unsetup(); kvm_arch_exit(); - kvm_exit_debug(); free_cpumask_var(cpus_hardware_enabled); __free_page(bad_page); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/