On Wed, Nov 12, 2014 at 11:17:16AM +0900, Joonsoo Kim wrote: > On Wed, Nov 12, 2014 at 03:22:41AM +0200, Kirill A. Shutemov wrote: > > On Tue, Nov 11, 2014 at 04:49:13PM -0800, Andrew Morton wrote: > > > On Tue, 11 Nov 2014 18:36:28 -0600 (CST) Christoph Lameter <cl@xxxxxxxxx> wrote: > > > > > > > On Tue, 11 Nov 2014, Andrew Morton wrote: > > > > > > > > > There's no point in doing > > > > > > > > > > #define GFP_SLAB_BUG_MASK (__GFP_DMA32|__GFP_HIGHMEM|~__GFP_BITS_MASK) > > > > > > > > > > because __GFP_DMA32|__GFP_HIGHMEM are already part of ~__GFP_BITS_MASK. > > > > > > > > ?? ~__GFP_BITS_MASK means bits 25 to 31 are set. > > > > > > > > __GFP_DMA32 is bit 2 and __GFP_HIGHMEM is bit 1. > > > > > > Ah, yes, OK. > > > > > > I suppose it's possible that __GFP_HIGHMEM was set. > > > > > > do_huge_pmd_anonymous_page > > > ->pte_alloc_one > > > ->alloc_pages(__userpte_alloc_gfp==__GFP_HIGHMEM) > > > > do_huge_pmd_anonymous_page > > alloc_hugepage_vma > > alloc_pages_vma(GFP_TRANSHUGE) > > > > GFP_TRANSHUGE contains GFP_HIGHUSER_MOVABLE, which has __GFP_HIGHMEM. > > Hello, Kirill. > > BTW, why does GFP_TRANSHUGE have MOVABLE flag despite it isn't > movable? After breaking hugepage, it could be movable, but, it may > prevent CMA from working correctly until break. Again, the same alloc vs. free gfp_mask: we want page allocator to move pages around to find space from THP, but resulting page is no really movable. I've tried to look into making THP movable: it requires quite a bit of infrastructure changes around rmap: try_to_unmap*(), remove_migration_pmd(), migration entries for PMDs, etc. I gets ugly pretty fast :-/ I probably need to give it second try. No promises. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>