On Mon, Jun 01, 2020 at 09:52:18AM -0000, tip-bot2 for Peter Zijlstra wrote: > The following commit has been merged into the sched/core branch of tip: > > Commit-ID: a148866489fbe243c936fe43e4525d8dbfa0318f > Gitweb: > https://git.kernel.org/tip/a148866489fbe243c936fe43e4525d8dbfa0318f > Author: Peter Zijlstra <[email protected]> > AuthorDate: Tue, 26 May 2020 18:11:04 +02:00 > Committer: Ingo Molnar <[email protected]> > CommitterDate: Thu, 28 May 2020 10:54:16 +02:00 > > sched: Replace rq::wake_list > > The recent commit: 90b5363acd47 ("sched: Clean up scheduler_ipi()") > got smp_call_function_single_async() subtly wrong. Even though it will > return -EBUSY when trying to re-use a csd, that condition is not > atomic and still requires external serialization. > > The change in ttwu_queue_remote() got this wrong. > > While on first reading ttwu_queue_remote() has an atomic test-and-set > that appears to serialize the use, the matching 'release' is not in > the right place to actually guarantee this serialization. > > The actual race is vs the sched_ttwu_pending() call in the idle loop; > that can run the wakeup-list without consuming the CSD. > > Instead of trying to chain the lists, merge them. > > Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > Signed-off-by: Ingo Molnar <[email protected]> > Link: https://lore.kernel.org/r/[email protected]
Looks good, thanks :)
