On Thu, Feb 27, 2014 at 05:31:50PM -0500, Steven Rostedt wrote: > Well, the perf ring buffer is vmalloced, right? That can cause a page > fault too.
On x86 they're typically not -- although we have a debug CONFIG option to test that code on x86 too. On SPARC/ARM etc.. we have to use vmalloc_user() because of cache aliasing (yay for VIPT).