Re: [RFC PATCH kernel] KVM: Stop leaking memory in debugfs

From: Paolo Bonzini
Date: Tue Aug 03 2021 - 09:29:35 EST


> So userspace can create kvm resources with duplicate names? That feels
> wrong to me.

Yes, the name is just the (pid, file descriptor). It's used only for
debugfs, and it's not really likely going to happen unless a program
does it on purpose, but the ugliness/wrongness is one of the reasons
why we now have a non-debugfs mechanism to retrieve the stats.

> But if all that is "duplicate" is the debugfs kvm directory, why not ask
> debugfs if it is already present before trying to create it again? That
> way you will not have debugfs complain about duplicate
> files/directories.

That would also be racy; it would need a simple mutex around
debugfs_lookup and debugfs_create_dir. But it would indeed avoid the
complaints altogether, so I'll prepare a patch. Thanks,

Paolo