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Wed, 3 Apr 2024 04:40:42 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , David Hildenbrand , Matthew Wilcox , Huang Ying , Gao Xiang , Yu Zhao , Yang Shi , Michal Hocko , Kefeng Wang , Barry Song <21cnbao@gmail.com>, Chris Li , Lance Yang Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 1/6] mm: swap: Remove CLUSTER_FLAG_HUGE from swap_cluster_info:flags Date: Wed, 3 Apr 2024 12:40:27 +0100 Message-Id: <20240403114032.1162100-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240403114032.1162100-1-ryan.roberts@arm.com> References: <20240403114032.1162100-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A0C4E40016 X-Stat-Signature: tgbtqa6apcu4sb4cygkpsp58zhe486zi X-Rspam-User: X-HE-Tag: 1712144445-914158 X-HE-Meta: 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 NS4XBkDm bBiUKFsdwzfh+Z36zodFiTc5Mtw1lRRaSc2RZU4zixc1kr7fwxewln09JZm2UlYlfih3oL+z42ed30qHn7bJxCu2ygX4jrabWpThitqxosMhq9cLykUWoAOSnMjM6eju2Ed7NRyRag7BsxGQ3mduDLD4/7nT97oowRwSdoN3oS45Qm7DkBmcAHtW9KZ8jwdMaVLXzkewpIcrF8c66q2vYMKPUa4inDrPEVbII 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: List-Subscribe: List-Unsubscribe: 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 shortcut a 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 functionally equivalent. That said, removing the fast path means that we will take a reference and trylock a large folio much more often, which we would like to avoid. The next patch will solve this. 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. Reviewed-by: "Huang, Ying" Signed-off-by: Ryan Roberts Acked-by: Chris Li Acked-by: David Hildenbrand --- include/linux/swap.h | 10 ---------- mm/huge_memory.c | 3 --- mm/swapfile.c | 47 ++++++++------------------------------------ 3 files changed, 8 insertions(+), 52 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index a211a0383425..f6f78198f000 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 @@ -590,15 +589,6 @@ 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 ea6d1f09a0b9..3ca9282a0dc9 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2844,9 +2844,6 @@ static void __split_huge_page(struct page *page, struct list_head *list, shmem_uncharge(folio->mapping->host, nr_dropped); remap_page(folio, nr); - if (folio_test_swapcache(folio)) - split_swap_cluster(folio->swap); - /* * set page to its compound_head when split to non order-0 pages, so * we can skip unlocking it below, since PG_locked is transferred to diff --git a/mm/swapfile.c b/mm/swapfile.c index 5e6d2304a2a4..0d44ee2b4f9c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -343,18 +343,6 @@ 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) { @@ -1027,7 +1015,7 @@ 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(ci, SWAPFILE_CLUSTER); memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER); unlock_cluster(ci); @@ -1365,7 +1353,6 @@ 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]; @@ -1373,7 +1360,6 @@ 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); @@ -1395,23 +1381,6 @@ 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; @@ -1519,22 +1488,23 @@ 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; @@ -1556,7 +1526,7 @@ 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)); } /** @@ -1622,8 +1592,7 @@ int free_swap_and_cache(swp_entry_t entry) } 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); put_swap_device(p);