include/linux/hugetlb.h: add synchronization information for new hugetlb specific flags

Add comments, no functional change.

Link: https://lkml.kernel.org/r/62a80585-2a73-10cc-4a2d-5721540d4ad2@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2021-02-24 12:09:08 -08:00 committed by Linus Torvalds
parent 6c03714901
commit d95c033777

View file

@ -480,14 +480,24 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
* HPG_restore_reserve - Set when a hugetlb page consumes a reservation at
* allocation time. Cleared when page is fully instantiated. Free
* routine checks flag to restore a reservation on error paths.
* Synchronization: Examined or modified by code that knows it has
* the only reference to page. i.e. After allocation but before use
* or when the page is being freed.
* HPG_migratable - Set after a newly allocated page is added to the page
* cache and/or page tables. Indicates the page is a candidate for
* migration.
* Synchronization: Initially set after new page allocation with no
* locking. When examined and modified during migration processing
* (isolate, migrate, putback) the hugetlb_lock is held.
* HPG_temporary - - Set on a page that is temporarily allocated from the buddy
* allocator. Typically used for migration target pages when no pages
* are available in the pool. The hugetlb free page path will
* immediately free pages with this flag set to the buddy allocator.
* Synchronization: Can be set after huge page allocation from buddy when
* code knows it has only reference. All other examinations and
* modifications require hugetlb_lock.
* HPG_freed - Set when page is on the free lists.
* Synchronization: hugetlb_lock held for examination and modification.
*/
enum hugetlb_page_flags {
HPG_restore_reserve = 0,