Re: [PATCH 2/4] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr()

[Al Viro]

On Fri, Jul 19, 2019 at 07:07:49PM -0400, Jeff Layton wrote:

> Al pointed out on IRC that vfree should be callable under spinlock.

Al had been near-terminally low on caffeine at the time, posted
a retraction a few minutes later and went to grab some coffee...

> It
> only sleeps if !in_interrupt(), and I think that should return true if
> we're holding a spinlock.

It can be used from RCU callbacks and all such; it *can't* be used from
under spinlock - on non-preempt builds there's no way to recognize that.