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cb3ea7684a
commit 55d134a7b499c77e7cfd0ee41046f3c376e791e5 upstream.
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: cf11e85fc0 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.