On Mon, 20 Aug 2018 10:55:16 +0200 Oscar Salvador <osalvador@xxxxxxxxxxxxxxxxxx> wrote: > From: Oscar Salvador <osalvador@xxxxxxx> > > Currently, NODEMASK_ALLOC allocates a nodemask_t with kmalloc when > NODES_SHIFT is higher than 8, otherwise it declares it within the stack. > > The comment says that the reasoning behind this, is that nodemask_t will be > 256 bytes when NODES_SHIFT is higher than 8, but this is not true. > For example, NODES_SHIFT = 9 will give us a 64 bytes nodemask_t. > Let us fix up the comment for that. > > Another thing is that it might make sense to let values lower than 128bytes > be allocated in the stack. > Although this all depends on the depth of the stack > (and this changes from function to function), I think that 64 bytes > is something we can easily afford. > So we could even bump the limit by 1 (from > 8 to > 9). > I agree. Such a change will reduce the amount of testing which the kmalloc version receives, but I assume there are enough people out there testing with large NODES_SHIFT values. And while we're looking at this, it would be nice to make NODES_SHIFT go away. Ensure that CONFIG_NODES_SHIFT always has a setting and use that directly.
