Thiago Jung Bauermann <bauer...@linux.vnet.ibm.com> writes: > Calling arch_update_cpu_topology from a CPU hotplug state machine callback > hits a deadlock because the function tries to get a read lock on > cpu_hotplug_lock while the state machine still holds a write lock on it. > > Since all callers of arch_update_cpu_topology except rtasd already hold > cpu_hotplug_lock, this patch changes the function to use > stop_machine_cpuslocked and creates a separate function for rtasd which > still tries to obtain the lock. > > Michael Bringmann investigated the bug and provided a detailed analysis > of the deadlock on this previous RFC for an alternate solution: > > https://patchwork.ozlabs.org/patch/771293/
Do we know when this broke? Or has it never worked? Should it go to stable? (can't in its current form AFAICS) > Signed-off-by: Thiago Jung Bauermann <bauer...@linux.vnet.ibm.com> > --- > > Notes: > This patch applies on tip/smp/hotplug, it should probably be carried > there. stop_machine_cpuslocked() doesn't exist in mainline so I think it has to be carried there right? cheers
