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Tue, 10 Oct 2023 07:21:23 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , David Hildenbrand , Matthew Wilcox , Huang Ying , Gao Xiang , Yu Zhao , Yang Shi , Michal Hocko Cc: Ryan Roberts , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v1 1/2] mm: swap: Remove CLUSTER_FLAG_HUGE from swap_cluster_info:flags Date: Tue, 10 Oct 2023 15:21:10 +0100 Message-Id: <20231010142111.3997780-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20231010142111.3997780-1-ryan.roberts@arm.com> References: <20231010142111.3997780-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: F04334024F X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: yp3hq6fud48nriexnxwapgu5ej9qkra9 X-HE-Tag: 1696947685-942705 X-HE-Meta: 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 hgRp3mYn JzjSFlowuo721N845p+9kxnW0H6mHY8P7hp5zvmcyISu/kCHyVTgO4gJb6Mp7GDHzfuaAV8qVamulxx2pUxNRJcVYQIm6OZWPd+Iqj1KTwUc8RMUhDIcOyJ8QGFsWpN8sP4Pwxe8X/tGxtswO5aU3uJ8m8aaeorrTtEYNSgX04m3s0wO7fw3HZXJKzjAwTy1a18+OOuPHOgtoLd8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: As preparation for supporting small-sized THP in the swap-out path, without first needing to split to order-0, Remove the CLUSTER_FLAG_HUGE, which, when present, always implies PMD-sized THP, which is the same as the cluster size. The only use of the flag was to determine whether a swap entry refers to a single page or a PMD-sized THP in swap_page_trans_huge_swapped(). Instead of relying on the flag, we now pass in nr_pages, which originates from the folio's number of pages. This allows the logic to work for folios of any order. The one snag is that one of the swap_page_trans_huge_swapped() call sites does not have the folio. But it was only being called there to avoid bothering to call __try_to_reclaim_swap() in some cases. __try_to_reclaim_swap() gets the folio and (via some other functions) calls swap_page_trans_huge_swapped(). So I've removed the problematic call site and believe the new logic should be equivalent. Removing CLUSTER_FLAG_HUGE also means we can remove split_swap_cluster() which used to be called during folio splitting, since split_swap_cluster()'s only job was to remove the flag. Signed-off-by: Ryan Roberts --- include/linux/swap.h | 10 ---------- mm/huge_memory.c | 3 --- mm/swapfile.c | 47 ++++++++------------------------------------ 3 files changed, 8 insertions(+), 52 deletions(-) -- 2.25.1 diff --git a/include/linux/swap.h b/include/linux/swap.h index 19f30a29e1f1..a073366a227c 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -259,7 +259,6 @@ struct swap_cluster_info { }; #define CLUSTER_FLAG_FREE 1 /* This cluster is free */ #define CLUSTER_FLAG_NEXT_NULL 2 /* This cluster has no next cluster */ -#define CLUSTER_FLAG_HUGE 4 /* This cluster is backing a transparent huge page */ /* * We assign a cluster to each CPU, so each CPU can allocate swap entry from @@ -595,15 +594,6 @@ static inline int add_swap_extent(struct swap_info_struct *sis, } #endif /* CONFIG_SWAP */ -#ifdef CONFIG_THP_SWAP -extern int split_swap_cluster(swp_entry_t entry); -#else -static inline int split_swap_cluster(swp_entry_t entry) -{ - return 0; -} -#endif - #ifdef CONFIG_MEMCG static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c9cbcbf6697e..46b3fb943207 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2597,9 +2597,6 @@ static void __split_huge_page(struct page *page, struct list_head *list, shmem_uncharge(head->mapping->host, nr_dropped); remap_page(folio, nr); - if (folio_test_swapcache(folio)) - split_swap_cluster(folio->swap); - for (i = 0; i < nr; i++) { struct page *subpage = head + i; if (subpage == page) diff --git a/mm/swapfile.c b/mm/swapfile.c index e52f486834eb..c668838fa660 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -342,18 +342,6 @@ static inline void cluster_set_null(struct swap_cluster_info *info) info->data = 0; } -static inline bool cluster_is_huge(struct swap_cluster_info *info) -{ - if (IS_ENABLED(CONFIG_THP_SWAP)) - return info->flags & CLUSTER_FLAG_HUGE; - return false; -} - -static inline void cluster_clear_huge(struct swap_cluster_info *info) -{ - info->flags &= ~CLUSTER_FLAG_HUGE; -} - static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, unsigned long offset) { @@ -1021,7 +1009,7 @@ static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) offset = idx * SWAPFILE_CLUSTER; ci = lock_cluster(si, offset); alloc_cluster(si, idx); - cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); + cluster_set_count_flag(ci, SWAPFILE_CLUSTER, 0); memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER); unlock_cluster(ci); @@ -1354,7 +1342,6 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry) ci = lock_cluster_or_swap_info(si, offset); if (size == SWAPFILE_CLUSTER) { - VM_BUG_ON(!cluster_is_huge(ci)); map = si->swap_map + offset; for (i = 0; i < SWAPFILE_CLUSTER; i++) { val = map[i]; @@ -1362,7 +1349,6 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry) if (val == SWAP_HAS_CACHE) free_entries++; } - cluster_clear_huge(ci); if (free_entries == SWAPFILE_CLUSTER) { unlock_cluster_or_swap_info(si, ci); spin_lock(&si->lock); @@ -1384,23 +1370,6 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry) unlock_cluster_or_swap_info(si, ci); } -#ifdef CONFIG_THP_SWAP -int split_swap_cluster(swp_entry_t entry) -{ - struct swap_info_struct *si; - struct swap_cluster_info *ci; - unsigned long offset = swp_offset(entry); - - si = _swap_info_get(entry); - if (!si) - return -EBUSY; - ci = lock_cluster(si, offset); - cluster_clear_huge(ci); - unlock_cluster(ci); - return 0; -} -#endif - static int swp_entry_cmp(const void *ent1, const void *ent2) { const swp_entry_t *e1 = ent1, *e2 = ent2; @@ -1508,22 +1477,23 @@ int swp_swapcount(swp_entry_t entry) } static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, - swp_entry_t entry) + swp_entry_t entry, + unsigned int nr_pages) { struct swap_cluster_info *ci; unsigned char *map = si->swap_map; unsigned long roffset = swp_offset(entry); - unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); + unsigned long offset = round_down(roffset, nr_pages); int i; bool ret = false; ci = lock_cluster_or_swap_info(si, offset); - if (!ci || !cluster_is_huge(ci)) { + if (!ci || nr_pages == 1) { if (swap_count(map[roffset])) ret = true; goto unlock_out; } - for (i = 0; i < SWAPFILE_CLUSTER; i++) { + for (i = 0; i < nr_pages; i++) { if (swap_count(map[offset + i])) { ret = true; break; @@ -1545,7 +1515,7 @@ static bool folio_swapped(struct folio *folio) if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio))) return swap_swapcount(si, entry) != 0; - return swap_page_trans_huge_swapped(si, entry); + return swap_page_trans_huge_swapped(si, entry, folio_nr_pages(folio)); } /** @@ -1606,8 +1576,7 @@ int free_swap_and_cache(swp_entry_t entry) p = _swap_info_get(entry); if (p) { count = __swap_entry_free(p, entry); - if (count == SWAP_HAS_CACHE && - !swap_page_trans_huge_swapped(p, entry)) + if (count == SWAP_HAS_CACHE) __try_to_reclaim_swap(p, swp_offset(entry), TTRS_UNMAPPED | TTRS_FULL); }