From: Zi Yan <[email protected]> We cannot swap PUD THPs, so split them before swap them out. PUD THPs will be split into PMD THPs, so that if THP_SWAP is enabled, PMD THPs can be swapped out as a whole.
Signed-off-by: Zi Yan <[email protected]> --- mm/swap_slots.c | 2 ++ mm/vmscan.c | 33 +++++++++++++++++++++++++++------ 2 files changed, 29 insertions(+), 6 deletions(-) diff --git a/mm/swap_slots.c b/mm/swap_slots.c index 3e6453573a89..65b8742a0446 100644 --- a/mm/swap_slots.c +++ b/mm/swap_slots.c @@ -312,6 +312,8 @@ swp_entry_t get_swap_page(struct page *page) entry.val = 0; if (PageTransHuge(page)) { + if (compound_order(page) == HPAGE_PUD_ORDER) + return entry; if (IS_ENABLED(CONFIG_THP_SWAP)) get_swap_pages(1, &entry, HPAGE_PMD_NR); goto out; diff --git a/mm/vmscan.c b/mm/vmscan.c index eae57d092931..12e169af663c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1244,7 +1244,21 @@ static unsigned int shrink_page_list(struct list_head *page_list, if (!PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; - if (PageTransHuge(page)) { + if (!PageTransHuge(page)) + goto try_to_swap; + if (compound_order(page) == HPAGE_PUD_ORDER) { + /* cannot split THP, skip it */ + if (!can_split_huge_pud_page(page, NULL)) + goto activate_locked; + /* Split PUD THPs before swapping */ + if (split_huge_pud_page_to_list(page, page_list)) + goto activate_locked; + else { + sc->nr_scanned -= (nr_pages - HPAGE_PMD_NR); + nr_pages = HPAGE_PMD_NR; + } + } + if (compound_order(page) == HPAGE_PMD_ORDER) { /* cannot split THP, skip it */ if (!can_split_huge_page(page, NULL)) goto activate_locked; @@ -1254,14 +1268,17 @@ static unsigned int shrink_page_list(struct list_head *page_list, * tail pages can be freed without IO. */ if (!compound_mapcount(page) && - split_huge_page_to_list(page, - page_list)) + split_huge_page_to_list(page, + page_list)) goto activate_locked; } +try_to_swap: if (!add_to_swap(page)) { if (!PageTransHuge(page)) goto activate_locked_split; /* Fallback to swap normal pages */ + VM_BUG_ON_PAGE(compound_order(page) != HPAGE_PMD_ORDER, + page); if (split_huge_page_to_list(page, page_list)) goto activate_locked; @@ -1278,6 +1295,7 @@ static unsigned int shrink_page_list(struct list_head *page_list, mapping = page_mapping(page); } } else if (unlikely(PageTransHuge(page))) { + VM_BUG_ON_PAGE(compound_order(page) != HPAGE_PMD_ORDER, page); /* Split file THP */ if (split_huge_page_to_list(page, page_list)) goto keep_locked; @@ -1303,9 +1321,12 @@ static unsigned int shrink_page_list(struct list_head *page_list, enum ttu_flags flags = ttu_flags | TTU_BATCH_FLUSH; bool was_swapbacked = PageSwapBacked(page); - if (unlikely(PageTransHuge(page))) - flags |= TTU_SPLIT_HUGE_PMD; - + if (unlikely(PageTransHuge(page))) { + if (compound_order(page) == HPAGE_PMD_ORDER) + flags |= TTU_SPLIT_HUGE_PMD; + else if (compound_order(page) == HPAGE_PUD_ORDER) + flags |= TTU_SPLIT_HUGE_PUD; + } if (!try_to_unmap(page, flags)) { stat->nr_unmap_fail += nr_pages; if (!was_swapbacked && PageSwapBacked(page)) -- 2.28.0
