From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Howells <dhowells@redhat.com>
Date: Wed, 04 Sep 2019 22:31:16 +0000
Subject: Re: [PATCH v12 10/12] namei: aggressively check for nd->root escape on ".." resolution
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>, Al Viro <viro@zeniv.linux.org.uk>, Jeff Layton <jlayton@kernel.org>, "J. Bruce Fields" <bfields@fieldses.org>, Arnd Bergmann <arnd@arndb.de>, David Howells <dhowells@redhat.com>, Shuah Khan <shuah@kernel.org>, Shuah Khan <skhan@linuxfoundation.org>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Christian Brauner <christian@brauner.io>, Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>, Eric Biederman <ebiederm@xmission.com>, Andy Lutomirski <luto@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Alexei Starovoitov <ast@kernel.org>, Tycho Andersen <tycho@tycho.ws>, David Drysdale <drysdale@google.com>, Chanho Min <chanho.min@lge.com>, Oleg Nesterov <oleg@redhat.com>, Rasmus

Linus Torvalds <torvalds@linux-foundation.org> wrote:

> > Hinting to userspace to do a retry (with -EAGAIN as you mention in your
> > other mail) wouldn't be a bad thing at all, though you'd almost
> > certainly get quite a few spurious -EAGAINs -- &{mount,rename}_lock are
> > global for the entire machine, after all.
> 
> I'd hope that we have some future (possibly very long-term)
> alternative that is not quite system-global, but yes, right now they
> are.

It ought to be reasonably easy to make them per-sb at least, I think.  We
don't allow cross-super rename, right?

David