From: Minchan Kim <minchan@xxxxxxxxxx> Subject: mm, THP, swap: move anonymous THP split logic to vmscan The add_to_swap aims to allocate swap_space(ie, swap slot and swapcache) so if it fails due to lack of space in case of THP or something(hdd swap but tries THP swapout) *caller* rather than add_to_swap itself should split the THP page and retry it with base page which is more natural. Link: http://lkml.kernel.org/r/20170515112522.32457-4-ying.huang@xxxxxxxxx Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/swap.h | 4 ++-- mm/swap_state.c | 23 ++++++----------------- mm/vmscan.c | 17 ++++++++++++++++- 3 files changed, 24 insertions(+), 20 deletions(-) diff -puN include/linux/swap.h~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan include/linux/swap.h --- a/include/linux/swap.h~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan +++ a/include/linux/swap.h @@ -353,7 +353,7 @@ extern struct address_space *swapper_spa >> SWAP_ADDRESS_SPACE_SHIFT]) extern unsigned long total_swapcache_pages(void); extern void show_swap_cache_info(void); -extern int add_to_swap(struct page *, struct list_head *list); +extern int add_to_swap(struct page *page); extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); extern void __delete_from_swap_cache(struct page *); @@ -473,7 +473,7 @@ static inline struct page *lookup_swap_c return NULL; } -static inline int add_to_swap(struct page *page, struct list_head *list) +static inline int add_to_swap(struct page *page) { return 0; } diff -puN mm/swap_state.c~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan mm/swap_state.c --- a/mm/swap_state.c~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan +++ a/mm/swap_state.c @@ -184,7 +184,7 @@ void __delete_from_swap_cache(struct pag * Allocate swap space for the page and add the page to the * swap cache. Caller needs to hold the page lock. */ -int add_to_swap(struct page *page, struct list_head *list) +int add_to_swap(struct page *page) { swp_entry_t entry; int err; @@ -192,12 +192,12 @@ int add_to_swap(struct page *page, struc VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageUptodate(page), page); -retry: entry = get_swap_page(page); if (!entry.val) - goto fail; + return 0; + if (mem_cgroup_try_charge_swap(page, entry)) - goto fail_free; + goto fail; /* * Radix-tree node allocations from PF_MEMALLOC contexts could @@ -218,23 +218,12 @@ retry: * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - goto fail_free; - - if (PageTransHuge(page)) { - err = split_huge_page_to_list(page, list); - if (err) { - delete_from_swap_cache(page); - return 0; - } - } + goto fail; return 1; -fail_free: - put_swap_page(page, entry); fail: - if (PageTransHuge(page) && !split_huge_page_to_list(page, list)) - goto retry; + put_swap_page(page, entry); return 0; } diff -puN mm/vmscan.c~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan mm/vmscan.c --- a/mm/vmscan.c~mm-thp-swap-move-anonymous-thp-split-logic-to-vmscan +++ a/mm/vmscan.c @@ -1125,8 +1125,23 @@ static unsigned long shrink_page_list(st !PageSwapCache(page)) { if (!(sc->gfp_mask & __GFP_IO)) goto keep_locked; - if (!add_to_swap(page, page_list)) + if (!add_to_swap(page)) { + if (!PageTransHuge(page)) + goto activate_locked; + /* Split THP and swap individual base pages */ + if (split_huge_page_to_list(page, page_list)) + goto activate_locked; + if (!add_to_swap(page)) + goto activate_locked; + } + + /* XXX: We don't support THP writes */ + if (PageTransHuge(page) && + split_huge_page_to_list(page, page_list)) { + delete_from_swap_cache(page); goto activate_locked; + } + may_enter_fs = 1; /* Adding to swap updated mapping */ _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
