On Wed, Dec 9, 2020 at 12:42 AM tip-bot2 for Andy Lutomirski <tip-bot2@xxxxxxxxxxxxx> wrote: > > The following commit has been merged into the x86/urgent branch of tip: > > Commit-ID: 2ecedd7569080fd05c1a457e8af2165afecfa29f > Gitweb: https://git.kernel.org/tip/2ecedd7569080fd05c1a457e8af2165afecfa29f > Author: Andy Lutomirski <luto@xxxxxxxxxx> > AuthorDate: Thu, 03 Dec 2020 21:07:04 -08:00 > Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > CommitterDate: Wed, 09 Dec 2020 09:37:43 +01:00 > > membarrier: Add an actual barrier before rseq_preempt() > > It seems 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. > > Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE") Whoops, this got mangled on its way to tip. This should be: Fixes: 2a36ab717e8f ("rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ") and this patch does not need to be backported.
