On 06/25/2013 08:43 AM, Benjamin Herrenschmidt wrote: > On Tue, 2013-06-25 at 12:58 +1000, Michael Ellerman wrote: >> On Tue, Jun 25, 2013 at 12:13:04PM +1000, Benjamin Herrenschmidt wrote: >>> On Tue, 2013-06-25 at 12:08 +1000, Michael Ellerman wrote: >>>> We're not checking for allocation failure, which we should be. >>>> >>>> But this code is only used on powermac and 85xx, so it should probably >>>> just be a TODO to fix this up to handle the failure. >>> >>> And what can we do if they fail ? >> >> Fail up the chain and not unplug the CPU presumably. > > BTW. Isn't Srivatsa series removing the need to stop_machine() for > unplug ? Yes. That should mean we should be able to use GFP_KERNEL no ? No, because whatever code was being executed in stop_machine() context would still be executed with interrupts disabled. So allocations that can sleep would continue to be forbidden in this path. In the CPU unplug sequence, the CPU_DYING notifications (and the surrounding code) is guaranteed to be run: a. _on_ the CPU going offline b. with interrupts disabled on that CPU. My patchset will retain these guarantees even after removing stop_machine(). And these are required for the correct execution of the code in this path, since they rely on these semantics. So I guess I'll retain the patch as it is. Thank you! Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
