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| author | Sang-Heon Jeon <ekffu200098@gmail.com> | 2026-05-03 17:42:25 +0900 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:31:01 -0700 |
| commit | ca8a95145288175ec8cbb074ba898a9871a826c6 (patch) | |
| tree | c9195773291202a44caa94702cb7cbc966139e61 /Documentation | |
| parent | da7b82037a01d5670ad53ff95e6bd8288e9bfb3a (diff) | |
| download | linux-next-history-ca8a95145288175ec8cbb074ba898a9871a826c6.tar.gz | |
mm/hugetlb_cma: restrict hugetlb_cma parameter to gigantic-page alignment
Existing hugetlb_cma parameter handling logic rejects sizes smaller than
one gigantic page, but rounds up larger sizes that are not a multiple of
it. The two behaviors are inconsistent and neither is documented.
To remove existing inconsistent and undefined behavior, restrict
hugetlb_cma parameter to only accept multiples of the gigantic page size.
After this restriction, the redundant round_up() in the allocation loop
can be removed.
The new restriction is also documented in kernel-parameters.txt.
Also, including other minor changes for readability improvement with no
functional change.
Link: https://lore.kernel.org/20260503084225.415980-1-ekffu200098@gmail.com
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Suggested-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 4d0f545fb3ec5..23be2f64439ca 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2100,6 +2100,10 @@ Kernel parameters Format: nn[KMGTPE] or (node format) <node>:nn[KMGTPE][,<node>:nn[KMGTPE]] + The size must be a multiple of the gigantic page size. + When using node format, this applies to each per-node size. + Missaligned values are dropped with a warning. + Reserve a CMA area of given size and allocate gigantic hugepages using the CMA allocator. If enabled, the boot-time allocation of gigantic hugepages is skipped. |