These patches came out of the "[RFC] mmap(MAP_CONTIG)" discussions at: http://lkml.kernel.org/r/21f1ec96-2822-1189-1c95-79a2bb491571@xxxxxxxxxx One suggestion in that thread was to create a friendlier interface that could be used by drivers and others outside core mm code to allocate a contiguous set of pages. The alloc_contig_range() interface is used for this purpose today by CMA and gigantic page allocation. However, this is not a general purpose interface. So, wrap alloc_contig_range() in the more general interface: struct page *find_alloc_contig_pages(unsigned int order, gfp_t gfp, int nid, nodemask_t *nodemask) No underlying changes are made to increase the likelihood that a contiguous set of pages can be found and allocated. Therefore, any user of this interface must deal with failure. The hope is that this interface will be able to satisfy some use cases today. If the "rate of failure" is too high to be useful, then more work can be put into methods to help increase the rate of successful allocations. Such a proposal was recently sent by Christoph Lameter "[RFC] Protect larger order pages from breaking up": http://lkml.kernel.org/r/alpine.DEB.2.20.1802091311090.3059@nuc-kabylake find_alloc_contig_pages() uses the same logic that exists today for scanning zones to look for contiguous ranges suitable for gigantic pages. The last patch in the series changes gigantic page allocation to use the new interface. Mike Kravetz (3): mm: make start_isolate_page_range() fail if already isolated mm: add find_alloc_contig_pages() interface mm/hugetlb: use find_alloc_contig_pages() to allocate gigantic pages include/linux/gfp.h | 12 +++++++ mm/hugetlb.c | 88 ++++-------------------------------------------- mm/page_alloc.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++---- mm/page_isolation.c | 10 +++++- 4 files changed, 118 insertions(+), 89 deletions(-) -- 2.13.6 -- 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>
