On Mon, Dec 02, 2019 at 09:48:43AM -0600, Haitao Huang wrote: > On Fri, 29 Nov 2019 17:13:14 -0600, Jarkko Sakkinen > <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote: > > > >+ > >+ for (c = 0 ; c < addp.length; c += PAGE_SIZE) { > >+ if (signal_pending(current)) { > >+ ret = -ERESTARTSYS; > >+ break; > >+ } > > This IOC is not idempotent as pages EADDed at this point can not be > re-EADDed again. So we can't return ERESTARTSYS Ah, and now I remember why I opted for modifying the parameters directly instead of including a "number processed" field. Andy pointed out the ERESTARTSYS thing in the original multi-page add RFC[*], so presumably updating the params and returning ERESTARTSYS is legal/acceptable. [*] https://lkml.kernel.org/r/CALCETrUb4X9_L9RXKhmyNpfSCsbNodP=BfbfO8Fz_efq24jp8w@xxxxxxxxxxxxxx