diff options
| -rw-r--r-- | include/linux/huge_mm.h | 7 | ||||
| -rw-r--r-- | mm/huge_memory.c | 20 | ||||
| -rw-r--r-- | mm/vmscan.c | 4 |
3 files changed, 27 insertions, 4 deletions
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index a3762d49ba39..d3b3e8fcc717 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -113,6 +113,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp, extern void prep_transhuge_page(struct page *page); extern void free_transhuge_page(struct page *page); +bool can_split_huge_page(struct page *page, int *pextra_pins); int split_huge_page_to_list(struct page *page, struct list_head *list); static inline int split_huge_page(struct page *page) { @@ -231,6 +232,12 @@ static inline void prep_transhuge_page(struct page *page) {} #define thp_get_unmapped_area NULL +static inline bool +can_split_huge_page(struct page *page, int *pextra_pins) +{ + BUILD_BUG(); + return false; +} static inline int split_huge_page_to_list(struct page *page, struct list_head *list) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 1a168e4bac4b..86975dec0ba1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2390,6 +2390,21 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount) return ret; } +/* Racy check whether the huge page can be split */ +bool can_split_huge_page(struct page *page, int *pextra_pins) +{ + int extra_pins; + + /* Additional pins from radix tree */ + if (PageAnon(page)) + extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; + else + extra_pins = HPAGE_PMD_NR; + if (pextra_pins) + *pextra_pins = extra_pins; + return total_mapcount(page) == page_count(page) - extra_pins - 1; +} + /* * This function splits huge page into normal pages. @page can point to any * subpage of huge page to split. Split doesn't change the position of @page. @@ -2437,7 +2452,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) ret = -EBUSY; goto out; } - extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; mapping = NULL; anon_vma_lock_write(anon_vma); } else { @@ -2449,8 +2463,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) goto out; } - /* Addidional pins from radix tree */ - extra_pins = HPAGE_PMD_NR; anon_vma = NULL; i_mmap_lock_read(mapping); } @@ -2459,7 +2471,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) * Racy check if we can split the page, before freeze_page() will * split PMDs */ - if (total_mapcount(head) != page_count(head) - extra_pins - 1) { + if (!can_split_huge_page(head, &extra_pins)) { ret = -EBUSY; goto out_unlock; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 729e37f02de6..abaf0215a352 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1125,6 +1125,10 @@ static unsigned long shrink_page_list(struct list_head *page_list, !PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; + /* cannot split THP, skip it */ + if (PageTransHuge(page) && + !can_split_huge_page(page, NULL)) + goto activate_locked; if (!add_to_swap(page)) { if (!PageTransHuge(page)) goto activate_locked; |