On Tue, Jul 23, 2019 at 02:05:11PM -0400, Jeff Layton wrote: > On Tue, 2019-07-23 at 10:55 -0700, Matthew Wilcox wrote: > > > HCH points out that xfs uses kvfree as a generic "free this no matter > > > what it is" sort of wrapper and expects the callers to work out whether > > > they might be freeing a vmalloc'ed address. If that sort of usage turns > > > out to be prevalent, then we may need another approach to clean this up. > > > > I think it's a bit of a landmine, to be honest. How about we have kvfree() > > call vfree_atomic() instead? > > Not a bad idea, though it means more overhead for the vfree case. > > Since we're spitballing here...could we have kvfree figure out whether > it's running in a context where it would need to queue it instead and > only do it in that case? > > We currently have to figure that out for the might_sleep_if anyway. We > could just have it DTRT instead of printk'ing and dumping the stack in > that case. I don't think we have a generic way to determine if we're currently holding a spinlock. ie this can fail: spin_lock(&my_lock); kvfree(p); spin_unlock(&my_lock); If we're preemptible, we can check the preempt count, but !CONFIG_PREEMPT doesn't record the number of spinlocks currently taken.
