Re: [PATCH] tracing/user_events: Run BPF program if attached

On Tue, 16 May 2023 18:46:29 -0700
Linus Torvalds [off-list ref] wrote:

So don't even ask for other GUP functionality, much less the "remote"
kind. Not going to happen. If you think you need access to remote
process memory, you had better do it in process context, or you had
better just think again.

So this code path is very much in user context (called directly by a
write system call). The issue that Alexei had was that it's also in an
rcu_read_lock() section.

I wonder if this all goes away if we switch to SRCU? That is, sleepable RCU.

-- Steve