On Tue, Jan 29, 2019 at 07:45:34PM +0000, Jonathan Cameron wrote: > On Tue, 29 Jan 2019 13:05:56 -0600 > Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Tue, Jan 29, 2019 at 09:51:05AM +0000, Jonathan Cameron wrote: > > > However, if there is NUMA description, but with bugs then we should > > > protect in depth. A simple example being that we declare 2 nodes, but > > > then use _PXM for a third. I've done that by accident and blows up > > > in a nasty fashion (not done it for a while, but probably still true). > > > > > > Given DSDT is only parsed long after SRAT we can just check on _PXM > > > queries. Or I suppose we could do a verification parse for all _PXM > > > entries and put out some warnings if they don't match SRAT entries? > > > > I'm assuming the crash happens when we call kmalloc_node() with a node > > not mentioned in SRAT. I think that's just sub-optimal implementation > > in kmalloc_node(). > > > > We *could* fail the allocation and return a NULL pointer, but I think > > even that is excessive. I think we should simply fall back to > > kmalloc(). We could print a one-time warning if that's useful. > > > > If kmalloc_node() for an unknown node fell back to kmalloc(), would > > anything else be required? > > It will deal with that case, but it may not be the only one. I > think there are interrupt related issues as well, but will have to > check. Sounds like a valid concern. Also, kmalloc() in general looks like a performance path, so maybe it would be better to address this on the other end, i.e., by ensuring that dev->numa_node always contains something valid for kmalloc(), interrupts, etc. Maybe set_dev_node() could be made smarter along that line? Bjorn
