On Wed, Apr 29, 2020 at 10:32:16AM -0400, Steven Rostedt wrote: > On Wed, 29 Apr 2020 16:10:04 +0200 > Joerg Roedel <jroe...@suse.de> wrote: > > > On Wed, Apr 29, 2020 at 10:07:31AM -0400, Steven Rostedt wrote: > > > Talking with Mathieu about this on IRC, he pointed out that my code does > > > have a vzalloc() that is called: > > > > > > in trace_pid_write() > > > > > > pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3); > > > > > > This is done when -P1,2 is on the trace-cmd command line. > > > > Yeah, I was guessing something like this, init_mm has a mapping which > > poking_mm has not. I currently try to reproduce this on one of my > > machines. > > Note, in use_temporary_mm(poking_mm), poking_mm only contains the page that
poking_mm should contain the full kernel map, the userspace part is 2 pages in a random location to alias two kernel pages. So a vmalloc fault _should_ work. > needs to be updated. But will get added to per_cpu(cpu_tlbstate.loaded_mm), > which appears to be the one that's not updated. > > -- Steve
