----- On Jul 16, 2020, at 7:26 PM, Nicholas Piggin npiggin@xxxxxxxxx wrote: [...] > > membarrier does replace barrier instructions on remote CPUs, which do > order accesses performed by the kernel on the user address space. So > membarrier should too I guess. > > Normal process context accesses like read(2) will do so because they > don't get filtered out from IPIs, but kernel threads using the mm may > not. But it should not be an issue, because membarrier's ordering is only with respect to submit and completion of io_uring requests, which are performed through system calls from the context of user-space threads, which are called from the right mm. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
