On Thu, Dec 3, 2020 at 9:07 PM Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > It seems to me that most RSEQ membarrier users will expect any > stores done before the membarrier() syscall to be visible to the > target task(s). While this is extremely likely to be true in > practice, nothing actually guarantees it by a strict reading of the > x86 manuals. Rather than providing this guarantee by accident and > potentially causing a problem down the road, just add an explicit > barrier. > > Cc: stable@xxxxxxxxxxxxxxx Fixes: 2a36ab717e8f ("rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ") which is new in 5.10, so it doesn't need cc:stable if it makes 5.10.