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SubjectRe: [PATCH v3 2/4] membarrier: Add an actual barrier before rseq_preempt()
On Thu, Dec 3, 2020 at 9:07 PM Andy Lutomirski <luto@kernel.org> 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@vger.kernel.org

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.

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