On Thu, 28 Mar 2019 12:45:18 -0700 Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > > I see solution is simple, but now we have a loop with GFP_ATOMIC > > allocations inside. How many "tracing spus" is this expected to loop > > over? Will not it exhaust atomically available pages and reliably fail > > in common configurations? > > Pavel > > Each one of these allocations is ~32 bytes and you do one per CPU. > Even with systems with a lot of CPUs that's not going to be tons. > ...and you only do it with GFP_ATOMIC when you're actively dropped > into kdb and debugging. It seems like going for simplicity is the > right call here, but of course if Steven or Daniel say that it has to > be done a different way then they're the true authorities. I really don't care. The code in question is only affected when we have CONFIG_KGDB_KDB enabled. But as it gets called from an atomic context, is it any different than what it was doing before? Except now with GFP_ATOMIC it is actually safer. Now, we could add some helper functions in the ring-buffer code to allow us to pre-allocate the ring_buffer_iter at boot up. Then we could pass in the per-allocated iters and use them here. -- Steve
