----- On Apr 30, 2020, at 12:16 PM, rostedt rost...@goodmis.org wrote: > On Thu, 30 Apr 2020 11:20:15 -0400 (EDT) > Mathieu Desnoyers <mathieu.desnoy...@efficios.com> wrote: > >> > The right fix is to call vmalloc_sync_mappings() right after allocating >> > tracing or perf buffers via v[zm]alloc(). >> >> Either right after allocation, or right before making the vmalloc'd data >> structure visible to the instrumentation. In the case of the pid filter, >> that would be the rcu_assign_pointer() which publishes the new pid filter >> table. >> >> As long as vmalloc_sync_mappings() is performed somewhere *between* >> allocation >> and publishing the pointer for instrumentation, it's fine. >> >> I'll let Steven decide on which approach works best for him. > > As stated in the other email, I don't see it having anything to do with > vmalloc, but with the per_cpu() allocation. I'll test this theory out by > not even allocating the pid masks and touching the per cpu data at every > event to see if it crashes.
As pointed out in my other email, per-cpu allocation uses vmalloc when size > PAGE_SIZE. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
