On 10.03.2020 19:06, Igor Druzhinin wrote: > During CPU down operation RCU callbacks are scheduled to finish > off some actions later as soon as CPU is fully dead (the same applies > to CPU up operation in case error path is taken). If in the same grace > period another CPU up operation is performed on the same CPU, RCU callback > will be called later on a CPU in a potentially wrong (already up again > instead of still being down) state leading to eventual state inconsistency > and/or crash. > > In order to avoid it - flush RCU callbacks explicitly before starting the > next CPU up/down operation. > > Reviewed-by: Juergen Gross <jgr...@suse.com> > Signed-off-by: Igor Druzhinin <igor.druzhi...@citrix.com> > --- > This got discovered trying to resume PV shim with multiple vCPUs on AMD > machine (where park_offline_cpus == 0). RCU callback responsible for > freeing percpu area on CPU offline got finally called after CPU went > online again as the guest performed regular vCPU offline/online operations > on resume. > > Note: this patch requires RCU series v4 from Juergen to be applied - > https://lists.xenproject.org/archives/html/xen-devel/2020-03/msg00668.html
I was about to apply the patch yesterday (I think) when I stumbled across this note. Is this actually still true? If so, would you mind helping me see the dependency? Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
