The quilt patch titled Subject: mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid has been removed from the -mm tree. Its filename was mm-hugetlb-pass-correct-order_per_bit-to-cma_declare_contiguous_nid.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Frank van der Linden fvdl@google.com Subject: mm/hugetlb: pass correct order_per_bit to cma_declare_contiguous_nid Date: Thu, 4 Apr 2024 16:25:15 +0000

The hugetlb_cma code passes 0 in the order_per_bit argument to cma_declare_contiguous_nid (the alignment, computed using the page order, is correctly passed in).

This causes a bit in the cma allocation bitmap to always represent a 4k page, making the bitmaps potentially very large, and slower.

It would create bitmaps that would be pretty big. E.g. for a 4k page size on x86, hugetlb_cma=64G would mean a bitmap size of (64G / 4k) / 8 == 2M. With HUGETLB_PAGE_ORDER as order_per_bit, as intended, this would be (64G / 2M) / 8 == 4k. So, that's quite a difference.

Also, this restricted the hugetlb_cma area to ((PAGE_SIZE << MAX_PAGE_ORDER) * 8) * PAGE_SIZE (e.g. 128G on x86) , since bitmap_alloc uses normal page allocation, and is thus restricted by MAX_PAGE_ORDER. Specifying anything about that would fail the CMA initialization.

So, correctly pass in the order instead.

Link: https://lkml.kernel.org/r/20240404162515.527802-2-fvdl@google.com Fixes: cf11e85fc08c ("mm: hugetlb: optionally allocate gigantic hugepages using cma") Signed-off-by: Frank van der Linden fvdl@google.com Acked-by: Roman Gushchin roman.gushchin@linux.dev Acked-by: David Hildenbrand david@redhat.com Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Muchun Song muchun.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/hugetlb.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-pass-correct-order_per_bit-to-cma_declare_contiguous_nid +++ a/mm/hugetlb.c @@ -7794,9 +7794,9 @@ void __init hugetlb_cma_reserve(int orde * huge page demotion. */ res = cma_declare_contiguous_nid(0, size, 0, - PAGE_SIZE << HUGETLB_PAGE_ORDER, - 0, false, name, - &hugetlb_cma[nid], nid); + PAGE_SIZE << HUGETLB_PAGE_ORDER, + HUGETLB_PAGE_ORDER, false, name, + &hugetlb_cma[nid], nid); if (res) { pr_warn("hugetlb_cma: reservation failed: err %d, node %d", res, nid); _

Patches currently in -mm which might be from fvdl@google.com are