From c5b5a3dd2c1fa61049b7789ce596faff4d659a61 Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Wed, 30 Jun 2021 18:51:42 -0700 Subject: mm: thp: refactor NUMA fault handling When the THP NUMA fault support was added THP migration was not supported yet. So the ad hoc THP migration was implemented in NUMA fault handling. Since v4.14 THP migration has been supported so it doesn't make too much sense to still keep another THP migration implementation rather than using the generic migration code. This patch reworks the NUMA fault handling to use generic migration implementation to migrate misplaced page. There is no functional change. After the refactor the flow of NUMA fault handling looks just like its PTE counterpart: Acquire ptl Prepare for migration (elevate page refcount) Release ptl Isolate page from lru and elevate page refcount Migrate the misplaced THP If migration fails just restore the old normal PMD. In the old code anon_vma lock was needed to serialize THP migration against THP split, but since then the THP code has been reworked a lot, it seems anon_vma lock is not required anymore to avoid the race. The page refcount elevation when holding ptl should prevent from THP split. Use migrate_misplaced_page() for both base page and THP NUMA hinting fault and remove all the dead and duplicate code. [dan.carpenter@oracle.com: fix a double unlock bug] Link: https://lkml.kernel.org/r/YLX8uYN01JmfLnlK@mwanda Link: https://lkml.kernel.org/r/20210518200801.7413-4-shy828301@gmail.com Signed-off-by: Yang Shi Signed-off-by: Dan Carpenter Acked-by: Mel Gorman Cc: Christian Borntraeger Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huang Ying Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Michal Hocko Cc: Vasily Gorbik Cc: Zi Yan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/migrate.h | 23 ----------------------- 1 file changed, 23 deletions(-) (limited to 'include') diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 7b7b73977278..9b7b7cd3bae9 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -99,14 +99,9 @@ static inline void __ClearPageMovable(struct page *page) #endif #ifdef CONFIG_NUMA_BALANCING -extern bool pmd_trans_migrating(pmd_t pmd); extern int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, int node); #else -static inline bool pmd_trans_migrating(pmd_t pmd) -{ - return false; -} static inline int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, int node) { @@ -114,24 +109,6 @@ static inline int migrate_misplaced_page(struct page *page, } #endif /* CONFIG_NUMA_BALANCING */ -#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) -extern int migrate_misplaced_transhuge_page(struct mm_struct *mm, - struct vm_area_struct *vma, - pmd_t *pmd, pmd_t entry, - unsigned long address, - struct page *page, int node); -#else -static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm, - struct vm_area_struct *vma, - pmd_t *pmd, pmd_t entry, - unsigned long address, - struct page *page, int node) -{ - return -EAGAIN; -} -#endif /* CONFIG_NUMA_BALANCING && CONFIG_TRANSPARENT_HUGEPAGE*/ - - #ifdef CONFIG_MIGRATION /* -- cgit v1.2.3-71-gd317