Re: [PATCH v2 1/1] psi: Fix uaf issue when psi trigger is destroyed while being polled

On Tue, Jan 11, 2022 at 11:11:32AM -0800, Linus Torvalds wrote:

Of course, in practice, for pointers, the whole "dereference off a pointer" on the read side *does* imply a barrier in all relevant situations. So yes, a smp_store_release() -> READ_ONCE() does work in practice, although it's technically wrong (in particular, it's wrong on alpha, because of the completely broken memory ordering that alpha has that doesn't even honor data dependencies as read-side orderings)

On a tangent, that actually works, even on Alpha, see commit d646285885154 ("alpha: Override READ_ONCE() with barriered implementation").