Re: [PATCH] x86/alternatives: remove false sharing in poke_int3_handler()

[Peter Zijlstra]

On Mon, Mar 24, 2025 at 08:53:31AM +0100, Eric Dumazet wrote:

> BTW the atomic_cond_read_acquire() part is never called even during my
> stress test.

Yes, IIRC this is due to text_poke_sync() serializing the state, as that
does a synchronous IPI broadcast, which by necessity requires all
previous INT3 handlers to complete.

You can only hit that case if the INT3 remains after step-3 (IOW you're
actively writing INT3 into the text). This is exceedingly rare.