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authorMuchun Song <songmuchun@bytedance.com>2021-06-30 18:48:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 20:47:26 -0700
commite6d41f12df0efcaa6e30b575d40f2529024cfce9 (patch)
tree9d547e73faa1f232a63284f3656a82a44630197d /Documentation
parent2d7a21715f25122779e2bed17db8c57aa01e922f (diff)
mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON
When using HUGETLB_PAGE_FREE_VMEMMAP, the freeing unused vmemmap pages associated with each HugeTLB page is default off. Now the vmemmap is PMD mapped. So there is no side effect when this feature is enabled with no HugeTLB pages in the system. Someone may want to enable this feature in the compiler time instead of using boot command line. So add a config to make it default on when someone do not want to enable it via command line. Link: https://lkml.kernel.org/r/20210616094915.34432-4-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Cc: Chen Huang <chenhuang5@huawei.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7a7da02b3bc6..c4e34420a485 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1577,6 +1577,9 @@
on: enable the feature
off: disable the feature
+ Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y,
+ the default is on.
+
This is not compatible with memory_hotplug.memmap_on_memory.
If both parameters are enabled, hugetlb_free_vmemmap takes
precedence over memory_hotplug.memmap_on_memory.