On 01/26/2012 01:39 PM, Benjamin Herrenschmidt wrote: > Can you explain to me a bit more the whole business in this patch set > about doing kmap_atomic() vs. manually trying to populate the PTEs ?
They're compressing pages and the allocator is trying getting very poor packing of compressed pages in to PAGE_SIZE chunks. So, they're moving to 2-page allocations that they need to be mapped contiguously to make it easier on the users of the allocator. > Why not just use two kmap atomic entries ? If interrupts are disabled > kmap_atomic() should give you contiguous ones I suppose I think you and I are at least on the same page on this one: https://lkml.org/lkml/2012/1/26/355 > (unless NMIs are allowed to use kmap_atomic, are they ?) Surely they can't be. Even if they could use it, they'd have to return the __kmap_atomic_idx back to the place where it started before they returned, so the interrupted code wouldn't notice. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
