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Wed, 27 Mar 2024 07:45:48 -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 v5 1/6] mm: swap: Remove CLUSTER_FLAG_HUGE from swap_cluster_info:flags Date: Wed, 27 Mar 2024 14:45:32 +0000 Message-Id: <20240327144537.4165578-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3A26C2001A X-Stat-Signature: x66o137qm78aez3bwc6bxbf5xi98akwc X-HE-Tag: 1711550751-430403 X-HE-Meta: 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 LJ/xhfYO zwRpNmdNvK4hoBeak4dr7BDIXoLqN83ViAKmOgWS3T5suWxSlobNv0L32UWqkaWcFpau3mNHpusi2R7fOme/Xg9d/bTKYGgwF2TjsuwJt0+UFwQZKMrkMkKPD0rla+JXKY+BlowMGV6hkqZvhojVFFBmaFbqttdMBjqqDupiJND/n5W5jhTi7qm/zukopK2YM4wJeaGExAyZ2gWM= 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. Signed-off-by: Ryan Roberts Reviewed-by: "Huang, Ying" 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 b49fcb8a16cc..8c1f3393994a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2961,9 +2961,6 @@ 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); 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Wed, 27 Mar 2024 07:45:50 -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 v5 2/6] mm: swap: free_swap_and_cache_nr() as batched free_swap_and_cache() Date: Wed, 27 Mar 2024 14:45:33 +0000 Message-Id: <20240327144537.4165578-3-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: A197110002C X-Rspam-User: X-Stat-Signature: cybjtuhqs8a7h7a9e4639g35gtjcimug X-Rspamd-Server: rspam01 X-HE-Tag: 1711550753-422590 X-HE-Meta: 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 3BOWv64e ZxyKyDuuUK5i87sUKQOkmQFCLCGeTvyb9Dt+wt8gX0tC22Qsn548fznUJ6vYTdCy/tBo87N1qwWEna+Xg6zibr3ZRez8EEOGObCCveg+sue1Q/XZdBbuypBcZZ94IrhXrVz2/ddFCrLRu+Kr8ogAdo/dFv8KFdGW0Rztq9OCwXiTiwYVboHeyx7bdLuXoeh9soN2AFFj6CEdAEPs= 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: Now that we no longer have a convenient flag in the cluster to determine if a folio is large, free_swap_and_cache() will take a reference and lock a large folio much more often, which could lead to contention and (e.g.) failure to split large folios, etc. Let's solve that problem by batch freeing swap and cache with a new function, free_swap_and_cache_nr(), to free a contiguous range of swap entries together. This allows us to first drop a reference to each swap slot before we try to release the cache folio. This means we only try to release the folio once, only taking the reference and lock once - much better than the previous 512 times for the 2M THP case. Contiguous swap entries are gathered in zap_pte_range() and madvise_free_pte_range() in a similar way to how present ptes are already gathered in zap_pte_range(). While we are at it, let's simplify by converting the return type of both functions to void. The return value was used only by zap_pte_range() to print a bad pte, and was ignored by everyone else, so the extra reporting wasn't exactly guaranteed. We will still get the warning with most of the information from get_swap_device(). With the batch version, we wouldn't know which pte was bad anyway so could print the wrong one. Signed-off-by: Ryan Roberts --- include/linux/pgtable.h | 28 +++++++++++++++ include/linux/swap.h | 12 +++++-- mm/internal.h | 48 +++++++++++++++++++++++++ mm/madvise.c | 12 ++++--- mm/memory.c | 13 +++---- mm/swapfile.c | 78 ++++++++++++++++++++++++++++++----------- 6 files changed, 157 insertions(+), 34 deletions(-) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 09c85c7bf9c2..8185939df1e8 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -708,6 +708,34 @@ static inline void pte_clear_not_present_full(struct mm_struct *mm, } #endif +#ifndef clear_not_present_full_ptes +/** + * clear_not_present_full_ptes - Clear consecutive not present PTEs. + * @mm: Address space the ptes represent. + * @addr: Address of the first pte. + * @ptep: Page table pointer for the first entry. + * @nr: Number of entries to clear. + * @full: Whether we are clearing a full mm. + * + * May be overridden by the architecture; otherwise, implemented as a simple + * loop over pte_clear_not_present_full(). + * + * Context: The caller holds the page table lock. The PTEs are all not present. + * The PTEs are all in the same PMD. + */ +static inline void clear_not_present_full_ptes(struct mm_struct *mm, + unsigned long addr, pte_t *ptep, unsigned int nr, int full) +{ + for (;;) { + pte_clear_not_present_full(mm, addr, ptep, full); + if (--nr == 0) + break; + ptep++; + addr += PAGE_SIZE; + } +} +#endif + #ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH extern pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, diff --git a/include/linux/swap.h b/include/linux/swap.h index f6f78198f000..5737236dc3ce 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -471,7 +471,7 @@ extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); extern void swapcache_free_entries(swp_entry_t *entries, int n); -extern int free_swap_and_cache(swp_entry_t); +extern void free_swap_and_cache_nr(swp_entry_t entry, int nr); int swap_type_of(dev_t device, sector_t offset); int find_first_swap(dev_t *device); extern unsigned int count_swap_pages(int, int); @@ -520,8 +520,9 @@ static inline void put_swap_device(struct swap_info_struct *si) #define free_pages_and_swap_cache(pages, nr) \ release_pages((pages), (nr)); -/* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */ -#define free_swap_and_cache(e) is_pfn_swap_entry(e) +static inline void free_swap_and_cache_nr(swp_entry_t entry, int nr) +{ +} static inline void free_swap_cache(struct folio *folio) { @@ -589,6 +590,11 @@ static inline int add_swap_extent(struct swap_info_struct *sis, } #endif /* CONFIG_SWAP */ +static inline void free_swap_and_cache(swp_entry_t entry) +{ + free_swap_and_cache_nr(entry, 1); +} + #ifdef CONFIG_MEMCG static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) { diff --git a/mm/internal.h b/mm/internal.h index 8e11f7b2da21..eadb79c3a357 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -11,6 +11,8 @@ #include #include #include +#include +#include #include struct folio_batch; @@ -189,6 +191,52 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, return min(ptep - start_ptep, max_nr); } + +/** + * swap_pte_batch - detect a PTE batch for a set of contiguous swap entries + * @start_ptep: Page table pointer for the first entry. + * @max_nr: The maximum number of table entries to consider. + * @entry: Swap entry recovered from the first table entry. + * + * Detect a batch of contiguous swap entries: consecutive (non-present) PTEs + * containing swap entries all with consecutive offsets and targeting the same + * swap type. + * + * max_nr must be at least one and must be limited by the caller so scanning + * cannot exceed a single page table. + * + * Return: the number of table entries in the batch. + */ +static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, + swp_entry_t entry) +{ + const pte_t *end_ptep = start_ptep + max_nr; + unsigned long expected_offset = swp_offset(entry) + 1; + unsigned int expected_type = swp_type(entry); + pte_t *ptep = start_ptep + 1; + + VM_WARN_ON(max_nr < 1); + VM_WARN_ON(non_swap_entry(entry)); + + while (ptep < end_ptep) { + pte_t pte = ptep_get(ptep); + + if (pte_none(pte) || pte_present(pte)) + break; + + entry = pte_to_swp_entry(pte); + + if (non_swap_entry(entry) || + swp_type(entry) != expected_type || + swp_offset(entry) != expected_offset) + break; + + expected_offset++; + ptep++; + } + + return ptep - start_ptep; +} #endif /* CONFIG_MMU */ void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio, diff --git a/mm/madvise.c b/mm/madvise.c index 1f77a51baaac..070bedb4996e 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -628,6 +628,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, struct folio *folio; int nr_swap = 0; unsigned long next; + int nr, max_nr; next = pmd_addr_end(addr, end); if (pmd_trans_huge(*pmd)) @@ -640,7 +641,8 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, return 0; flush_tlb_batched_pending(mm); arch_enter_lazy_mmu_mode(); - for (; addr != end; pte++, addr += PAGE_SIZE) { + for (; addr != end; pte += nr, addr += PAGE_SIZE * nr) { + nr = 1; ptent = ptep_get(pte); if (pte_none(ptent)) @@ -655,9 +657,11 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, entry = pte_to_swp_entry(ptent); if (!non_swap_entry(entry)) { - nr_swap--; - free_swap_and_cache(entry); - pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); + max_nr = (end - addr) / PAGE_SIZE; + nr = swap_pte_batch(pte, max_nr, entry); + nr_swap -= nr; + free_swap_and_cache_nr(entry, nr); + clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm); } else if (is_hwpoison_entry(entry) || is_poisoned_swp_entry(entry)) { pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); diff --git a/mm/memory.c b/mm/memory.c index 36191a9c799c..9d844582ba38 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1631,12 +1631,13 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, folio_remove_rmap_pte(folio, page, vma); folio_put(folio); } else if (!non_swap_entry(entry)) { - /* Genuine swap entry, hence a private anon page */ + max_nr = (end - addr) / PAGE_SIZE; + nr = swap_pte_batch(pte, max_nr, entry); + /* Genuine swap entries, hence a private anon pages */ if (!should_zap_cows(details)) continue; - rss[MM_SWAPENTS]--; - if (unlikely(!free_swap_and_cache(entry))) - print_bad_pte(vma, addr, ptent, NULL); + rss[MM_SWAPENTS] -= nr; + free_swap_and_cache_nr(entry, nr); } else if (is_migration_entry(entry)) { folio = pfn_swap_entry_folio(entry); if (!should_zap_folio(details, folio)) @@ -1659,8 +1660,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, pr_alert("unrecognized swap entry 0x%lx\n", entry.val); WARN_ON_ONCE(1); } - pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); - zap_install_uffd_wp_if_needed(vma, addr, pte, 1, details, ptent); + clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm); + zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent); } while (pte += nr, addr += PAGE_SIZE * nr, addr != end); add_mm_rss_vec(mm, rss); diff --git a/mm/swapfile.c b/mm/swapfile.c index 0d44ee2b4f9c..cedfc82d37e5 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -130,7 +130,11 @@ static inline unsigned char swap_count(unsigned char ent) /* Reclaim the swap entry if swap is getting full*/ #define TTRS_FULL 0x4 -/* returns 1 if swap entry is freed */ +/* + * returns number of pages in the folio that backs the swap entry. If positive, + * the folio was reclaimed. If negative, the folio was not reclaimed. If 0, no + * folio was associated with the swap entry. + */ static int __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset, unsigned long flags) { @@ -155,6 +159,7 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si, ret = folio_free_swap(folio); folio_unlock(folio); } + ret = ret ? folio_nr_pages(folio) : -folio_nr_pages(folio); folio_put(folio); return ret; } @@ -895,7 +900,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si, swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); spin_lock(&si->lock); /* entry was freed successfully, try to use this again */ - if (swap_was_freed) + if (swap_was_freed > 0) goto checks; goto scan; /* check next one */ } @@ -1572,32 +1577,63 @@ bool folio_free_swap(struct folio *folio) return true; } -/* - * Free the swap entry like above, but also try to - * free the page cache entry if it is the last user. - */ -int free_swap_and_cache(swp_entry_t entry) +void free_swap_and_cache_nr(swp_entry_t entry, int nr) { - struct swap_info_struct *p; - unsigned char count; + unsigned long end = swp_offset(entry) + nr; + unsigned int type = swp_type(entry); + struct swap_info_struct *si; + unsigned long offset; if (non_swap_entry(entry)) - return 1; + return; - p = get_swap_device(entry); - if (p) { - if (WARN_ON(data_race(!p->swap_map[swp_offset(entry)]))) { - put_swap_device(p); - return 0; - } + si = get_swap_device(entry); + if (!si) + return; - count = __swap_entry_free(p, entry); - if (count == SWAP_HAS_CACHE) - __try_to_reclaim_swap(p, swp_offset(entry), + if (WARN_ON(end > si->max)) + goto out; + + /* + * First free all entries in the range. + */ + for (offset = swp_offset(entry); offset < end; offset++) { + if (!WARN_ON(data_race(!si->swap_map[offset]))) + __swap_entry_free(si, swp_entry(type, offset)); + } + + /* + * Now go back over the range trying to reclaim the swap cache. This is + * more efficient for large folios because we will only try to reclaim + * the swap once per folio in the common case. If we do + * __swap_entry_free() and __try_to_reclaim_swap() in the same loop, the + * latter will get a reference and lock the folio for every individual + * page but will only succeed once the swap slot for every subpage is + * zero. + */ + for (offset = swp_offset(entry); offset < end; offset += nr) { + nr = 1; + if (READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { + /* + * Folios are always naturally aligned in swap so + * advance forward to the next boundary. Zero means no + * folio was found for the swap entry, so advance by 1 + * in this case. Negative value means folio was found + * but could not be reclaimed. Here we can still advance + * to the next boundary. + */ + nr = __try_to_reclaim_swap(si, offset, TTRS_UNMAPPED | TTRS_FULL); - put_swap_device(p); + if (nr == 0) + nr = 1; + else if (nr < 0) + nr = -nr; + nr = ALIGN(offset + 1, nr) - offset; + } } - return p != NULL; + +out: + put_swap_device(si); } #ifdef CONFIG_HIBERNATION From patchwork Wed Mar 27 14:45:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13606751 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37509CD11DD for ; Wed, 27 Mar 2024 14:46:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ADD506B00A0; Wed, 27 Mar 2024 10:45:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A65DE6B00A2; Wed, 27 Mar 2024 10:45:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8E28C6B00A3; 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Wed, 27 Mar 2024 07:45:52 -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 v5 3/6] mm: swap: Simplify struct percpu_cluster Date: Wed, 27 Mar 2024 14:45:34 +0000 Message-Id: <20240327144537.4165578-4-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: mdpnqqj7g1zi5ej9k88btw4r7omcdkeb X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 7CD434001A X-HE-Tag: 1711550755-672751 X-HE-Meta: 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 w+CQSxIM 9J9LCs1msLxABGfmXxTCp/6Zp3LURxt/2b6ey96yXM42qDfFNw8YmuP0QOqFavybplwH9bo+dj3eAAkVp6CXwzbrIPBQiutOldrh2hc7ykOkOMmhIPoSzshucaLSKBVyTAqskMfsC6Y0sOitF+OwN7ywUQeCoSvM/4gyaxWFOEMBUGh5tSXVRF/bj7Y0M2hFgUPLHByTw4QmuSqiv06FvXwtdeZuYKjzwQKAc 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: struct percpu_cluster stores the index of cpu's current cluster and the offset of the next entry that will be allocated for the cpu. These two pieces of information are redundant because the cluster index is just (offset / SWAPFILE_CLUSTER). The only reason for explicitly keeping the cluster index is because the structure used for it also has a flag to indicate "no cluster". However this data structure also contains a spin lock, which is never used in this context, as a side effect the code copies the spinlock_t structure, which is questionable coding practice in my view. So let's clean this up and store only the next offset, and use a sentinal value (SWAP_NEXT_INVALID) to indicate "no cluster". SWAP_NEXT_INVALID is chosen to be 0, because 0 will never be seen legitimately; The first page in the swap file is the swap header, which is always marked bad to prevent it from being allocated as an entry. This also prevents the cluster to which it belongs being marked free, so it will never appear on the free list. This change saves 16 bytes per cpu. And given we are shortly going to extend this mechanism to be per-cpu-AND-per-order, we will end up saving 16 * 9 = 144 bytes per cpu, which adds up if you have 256 cpus in the system. Reviewed-by: "Huang, Ying" Signed-off-by: Ryan Roberts --- include/linux/swap.h | 9 ++++++++- mm/swapfile.c | 22 +++++++++++----------- 2 files changed, 19 insertions(+), 12 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 5737236dc3ce..5e1e4f5bf0cb 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -260,13 +260,20 @@ 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 */ +/* + * The first page in the swap file is the swap header, which is always marked + * bad to prevent it from being allocated as an entry. This also prevents the + * cluster to which it belongs being marked free. Therefore 0 is safe to use as + * a sentinel to indicate next is not valid in percpu_cluster. + */ +#define SWAP_NEXT_INVALID 0 + /* * We assign a cluster to each CPU, so each CPU can allocate swap entry from * its own cluster and swapout sequentially. The purpose is to optimize swapout * throughput. */ struct percpu_cluster { - struct swap_cluster_info index; /* Current cluster index */ unsigned int next; /* Likely next allocation offset */ }; diff --git a/mm/swapfile.c b/mm/swapfile.c index cedfc82d37e5..1393966b77af 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -609,7 +609,7 @@ scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, return false; percpu_cluster = this_cpu_ptr(si->percpu_cluster); - cluster_set_null(&percpu_cluster->index); + percpu_cluster->next = SWAP_NEXT_INVALID; return true; } @@ -622,14 +622,14 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, { struct percpu_cluster *cluster; struct swap_cluster_info *ci; - unsigned long tmp, max; + unsigned int tmp, max; new_cluster: cluster = this_cpu_ptr(si->percpu_cluster); - if (cluster_is_null(&cluster->index)) { + tmp = cluster->next; + if (tmp == SWAP_NEXT_INVALID) { if (!cluster_list_empty(&si->free_clusters)) { - cluster->index = si->free_clusters.head; - cluster->next = cluster_next(&cluster->index) * + tmp = cluster_next(&si->free_clusters.head) * SWAPFILE_CLUSTER; } else if (!cluster_list_empty(&si->discard_clusters)) { /* @@ -649,9 +649,7 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, * Other CPUs can use our cluster if they can't find a free cluster, * check if there is still free entry in the cluster */ - tmp = cluster->next; - max = min_t(unsigned long, si->max, - (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); + max = min_t(unsigned long, si->max, ALIGN(tmp + 1, SWAPFILE_CLUSTER)); if (tmp < max) { ci = lock_cluster(si, tmp); while (tmp < max) { @@ -662,12 +660,13 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, unlock_cluster(ci); } if (tmp >= max) { - cluster_set_null(&cluster->index); + cluster->next = SWAP_NEXT_INVALID; goto new_cluster; } - cluster->next = tmp + 1; *offset = tmp; *scan_base = tmp; + tmp += 1; + cluster->next = tmp < max ? tmp : SWAP_NEXT_INVALID; return true; } @@ -3138,8 +3137,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) } for_each_possible_cpu(cpu) { struct percpu_cluster *cluster; + cluster = per_cpu_ptr(p->percpu_cluster, cpu); - cluster_set_null(&cluster->index); + cluster->next = SWAP_NEXT_INVALID; } } else { atomic_inc(&nr_rotate_swap); From patchwork Wed Mar 27 14:45:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13606752 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C084AC47DD9 for ; Wed, 27 Mar 2024 14:46:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB38C6B00A2; Wed, 27 Mar 2024 10:45:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C152A6B00A3; Wed, 27 Mar 2024 10:45:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A41266B00A4; 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Wed, 27 Mar 2024 07:45:54 -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 v5 4/6] mm: swap: Allow storage of all mTHP orders Date: Wed, 27 Mar 2024 14:45:35 +0000 Message-Id: <20240327144537.4165578-5-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7E98714000D X-Stat-Signature: dx3xwip636ejxgwph5pxki9nnki9io4x X-HE-Tag: 1711550757-224264 X-HE-Meta: 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 BctBzhwi M3roXxrRgXEsSX68+SnUsSWl2I33rQdnwil6tVOxIju10SixpnELRC/TlTCvxwd0rhvbiow7MIDg2psebslBiVkGGp92ldQ92KkprEA8CQkRRSW89XHOtOCrGgabvzgoPp3zLFEcVZMGVLd17yCs9lYnzlxJJakmdqPE6 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: Multi-size THP enables performance improvements by allocating large, pte-mapped folios for anonymous memory. However I've observed that on an arm64 system running a parallel workload (e.g. kernel compilation) across many cores, under high memory pressure, the speed regresses. This is due to bottlenecking on the increased number of TLBIs added due to all the extra folio splitting when the large folios are swapped out. Therefore, solve this regression by adding support for swapping out mTHP without needing to split the folio, just like is already done for PMD-sized THP. This change only applies when CONFIG_THP_SWAP is enabled, and when the swap backing store is a non-rotating block device. These are the same constraints as for the existing PMD-sized THP swap-out support. Note that no attempt is made to swap-in (m)THP here - this is still done page-by-page, like for PMD-sized THP. But swapping-out mTHP is a prerequisite for swapping-in mTHP. The main change here is to improve the swap entry allocator so that it can allocate any power-of-2 number of contiguous entries between [1, (1 << PMD_ORDER)]. This is done by allocating a cluster for each distinct order and allocating sequentially from it until the cluster is full. This ensures that we don't need to search the map and we get no fragmentation due to alignment padding for different orders in the cluster. If there is no current cluster for a given order, we attempt to allocate a free cluster from the list. If there are no free clusters, we fail the allocation and the caller can fall back to splitting the folio and allocates individual entries (as per existing PMD-sized THP fallback). The per-order current clusters are maintained per-cpu using the existing infrastructure. This is done to avoid interleving pages from different tasks, which would prevent IO being batched. This is already done for the order-0 allocations so we follow the same pattern. As is done for order-0 per-cpu clusters, the scanner now can steal order-0 entries from any per-cpu-per-order reserved cluster. This ensures that when the swap file is getting full, space doesn't get tied up in the per-cpu reserves. This change only modifies swap to be able to accept any order mTHP. It doesn't change the callers to elide doing the actual split. That will be done in separate changes. Signed-off-by: Ryan Roberts Reviewed-by: "Huang, Ying" --- include/linux/swap.h | 10 ++- mm/swap_slots.c | 6 +- mm/swapfile.c | 175 ++++++++++++++++++++++++------------------- 3 files changed, 109 insertions(+), 82 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 5e1e4f5bf0cb..11c53692f65f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -268,13 +268,19 @@ struct swap_cluster_info { */ #define SWAP_NEXT_INVALID 0 +#ifdef CONFIG_THP_SWAP +#define SWAP_NR_ORDERS (PMD_ORDER + 1) +#else +#define SWAP_NR_ORDERS 1 +#endif + /* * We assign a cluster to each CPU, so each CPU can allocate swap entry from * its own cluster and swapout sequentially. The purpose is to optimize swapout * throughput. */ struct percpu_cluster { - unsigned int next; /* Likely next allocation offset */ + unsigned int next[SWAP_NR_ORDERS]; /* Likely next allocation offset */ }; struct swap_cluster_list { @@ -471,7 +477,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio); bool folio_free_swap(struct folio *folio); void put_swap_folio(struct folio *folio, swp_entry_t entry); extern swp_entry_t get_swap_page_of_type(int); -extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size); +extern int get_swap_pages(int n, swp_entry_t swp_entries[], int order); extern int add_swap_count_continuation(swp_entry_t, gfp_t); extern void swap_shmem_alloc(swp_entry_t); extern int swap_duplicate(swp_entry_t); diff --git a/mm/swap_slots.c b/mm/swap_slots.c index 53abeaf1371d..13ab3b771409 100644 --- a/mm/swap_slots.c +++ b/mm/swap_slots.c @@ -264,7 +264,7 @@ static int refill_swap_slots_cache(struct swap_slots_cache *cache) cache->cur = 0; if (swap_slot_cache_active) cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, - cache->slots, 1); + cache->slots, 0); return cache->nr; } @@ -311,7 +311,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio) if (folio_test_large(folio)) { if (IS_ENABLED(CONFIG_THP_SWAP)) - get_swap_pages(1, &entry, folio_nr_pages(folio)); + get_swap_pages(1, &entry, folio_order(folio)); goto out; } @@ -343,7 +343,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio) goto out; } - get_swap_pages(1, &entry, 1); + get_swap_pages(1, &entry, 0); out: if (mem_cgroup_try_charge_swap(folio, entry)) { put_swap_folio(folio, entry); diff --git a/mm/swapfile.c b/mm/swapfile.c index 1393966b77af..d56cdc547a06 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -278,15 +278,15 @@ static void discard_swap_cluster(struct swap_info_struct *si, #ifdef CONFIG_THP_SWAP #define SWAPFILE_CLUSTER HPAGE_PMD_NR -#define swap_entry_size(size) (size) +#define swap_entry_order(order) (order) #else #define SWAPFILE_CLUSTER 256 /* - * Define swap_entry_size() as constant to let compiler to optimize + * Define swap_entry_order() as constant to let compiler to optimize * out some code if !CONFIG_THP_SWAP */ -#define swap_entry_size(size) 1 +#define swap_entry_order(order) 0 #endif #define LATENCY_LIMIT 256 @@ -551,10 +551,12 @@ static void free_cluster(struct swap_info_struct *si, unsigned long idx) /* * The cluster corresponding to page_nr will be used. The cluster will be - * removed from free cluster list and its usage counter will be increased. + * removed from free cluster list and its usage counter will be increased by + * count. */ -static void inc_cluster_info_page(struct swap_info_struct *p, - struct swap_cluster_info *cluster_info, unsigned long page_nr) +static void add_cluster_info_page(struct swap_info_struct *p, + struct swap_cluster_info *cluster_info, unsigned long page_nr, + unsigned long count) { unsigned long idx = page_nr / SWAPFILE_CLUSTER; @@ -563,9 +565,19 @@ static void inc_cluster_info_page(struct swap_info_struct *p, if (cluster_is_free(&cluster_info[idx])) alloc_cluster(p, idx); - VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); + VM_BUG_ON(cluster_count(&cluster_info[idx]) + count > SWAPFILE_CLUSTER); cluster_set_count(&cluster_info[idx], - cluster_count(&cluster_info[idx]) + 1); + cluster_count(&cluster_info[idx]) + count); +} + +/* + * The cluster corresponding to page_nr will be used. The cluster will be + * removed from free cluster list and its usage counter will be increased by 1. + */ +static void inc_cluster_info_page(struct swap_info_struct *p, + struct swap_cluster_info *cluster_info, unsigned long page_nr) +{ + add_cluster_info_page(p, cluster_info, page_nr, 1); } /* @@ -595,7 +607,7 @@ static void dec_cluster_info_page(struct swap_info_struct *p, */ static bool scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, - unsigned long offset) + unsigned long offset, int order) { struct percpu_cluster *percpu_cluster; bool conflict; @@ -609,24 +621,39 @@ scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, return false; percpu_cluster = this_cpu_ptr(si->percpu_cluster); - percpu_cluster->next = SWAP_NEXT_INVALID; + percpu_cluster->next[order] = SWAP_NEXT_INVALID; + return true; +} + +static inline bool swap_range_empty(char *swap_map, unsigned int start, + unsigned int nr_pages) +{ + unsigned int i; + + for (i = 0; i < nr_pages; i++) { + if (swap_map[start + i]) + return false; + } + return true; } /* - * Try to get a swap entry from current cpu's swap entry pool (a cluster). This - * might involve allocating a new cluster for current CPU too. + * Try to get swap entries with specified order from current cpu's swap entry + * pool (a cluster). This might involve allocating a new cluster for current CPU + * too. */ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, - unsigned long *offset, unsigned long *scan_base) + unsigned long *offset, unsigned long *scan_base, int order) { + unsigned int nr_pages = 1 << order; struct percpu_cluster *cluster; struct swap_cluster_info *ci; unsigned int tmp, max; new_cluster: cluster = this_cpu_ptr(si->percpu_cluster); - tmp = cluster->next; + tmp = cluster->next[order]; if (tmp == SWAP_NEXT_INVALID) { if (!cluster_list_empty(&si->free_clusters)) { tmp = cluster_next(&si->free_clusters.head) * @@ -647,26 +674,27 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, /* * Other CPUs can use our cluster if they can't find a free cluster, - * check if there is still free entry in the cluster + * check if there is still free entry in the cluster, maintaining + * natural alignment. */ max = min_t(unsigned long, si->max, ALIGN(tmp + 1, SWAPFILE_CLUSTER)); if (tmp < max) { ci = lock_cluster(si, tmp); while (tmp < max) { - if (!si->swap_map[tmp]) + if (swap_range_empty(si->swap_map, tmp, nr_pages)) break; - tmp++; + tmp += nr_pages; } unlock_cluster(ci); } if (tmp >= max) { - cluster->next = SWAP_NEXT_INVALID; + cluster->next[order] = SWAP_NEXT_INVALID; goto new_cluster; } *offset = tmp; *scan_base = tmp; - tmp += 1; - cluster->next = tmp < max ? tmp : SWAP_NEXT_INVALID; + tmp += nr_pages; + cluster->next[order] = tmp < max ? tmp : SWAP_NEXT_INVALID; return true; } @@ -796,13 +824,14 @@ static bool swap_offset_available_and_locked(struct swap_info_struct *si, static int scan_swap_map_slots(struct swap_info_struct *si, unsigned char usage, int nr, - swp_entry_t slots[]) + swp_entry_t slots[], int order) { struct swap_cluster_info *ci; unsigned long offset; unsigned long scan_base; unsigned long last_in_cluster = 0; int latency_ration = LATENCY_LIMIT; + unsigned int nr_pages = 1 << order; int n_ret = 0; bool scanned_many = false; @@ -817,6 +846,25 @@ static int scan_swap_map_slots(struct swap_info_struct *si, * And we let swap pages go all over an SSD partition. Hugh */ + if (order > 0) { + /* + * Should not even be attempting large allocations when huge + * page swap is disabled. Warn and fail the allocation. + */ + if (!IS_ENABLED(CONFIG_THP_SWAP) || + nr_pages > SWAPFILE_CLUSTER) { + VM_WARN_ON_ONCE(1); + return 0; + } + + /* + * Swapfile is not block device or not using clusters so unable + * to allocate large entries. + */ + if (!(si->flags & SWP_BLKDEV) || !si->cluster_info) + return 0; + } + si->flags += SWP_SCANNING; /* * Use percpu scan base for SSD to reduce lock contention on @@ -831,8 +879,11 @@ static int scan_swap_map_slots(struct swap_info_struct *si, /* SSD algorithm */ if (si->cluster_info) { - if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) + if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base, order)) { + if (order > 0) + goto no_page; goto scan; + } } else if (unlikely(!si->cluster_nr--)) { if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { si->cluster_nr = SWAPFILE_CLUSTER - 1; @@ -874,13 +925,16 @@ static int scan_swap_map_slots(struct swap_info_struct *si, checks: if (si->cluster_info) { - while (scan_swap_map_ssd_cluster_conflict(si, offset)) { + while (scan_swap_map_ssd_cluster_conflict(si, offset, order)) { /* take a break if we already got some slots */ if (n_ret) goto done; if (!scan_swap_map_try_ssd_cluster(si, &offset, - &scan_base)) + &scan_base, order)) { + if (order > 0) + goto no_page; goto scan; + } } } if (!(si->flags & SWP_WRITEOK)) @@ -911,11 +965,11 @@ static int scan_swap_map_slots(struct swap_info_struct *si, else goto done; } - WRITE_ONCE(si->swap_map[offset], usage); - inc_cluster_info_page(si, si->cluster_info, offset); + memset(si->swap_map + offset, usage, nr_pages); + add_cluster_info_page(si, si->cluster_info, offset, nr_pages); unlock_cluster(ci); - swap_range_alloc(si, offset, 1); + swap_range_alloc(si, offset, nr_pages); slots[n_ret++] = swp_entry(si->type, offset); /* got enough slots or reach max slots? */ @@ -936,8 +990,10 @@ static int scan_swap_map_slots(struct swap_info_struct *si, /* try to get more slots in cluster */ if (si->cluster_info) { - if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) + if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base, order)) goto checks; + if (order > 0) + goto done; } else if (si->cluster_nr && !si->swap_map[++offset]) { /* non-ssd case, still more slots in cluster? */ --si->cluster_nr; @@ -964,11 +1020,13 @@ static int scan_swap_map_slots(struct swap_info_struct *si, } done: - set_cluster_next(si, offset + 1); + if (order == 0) + set_cluster_next(si, offset + 1); si->flags -= SWP_SCANNING; return n_ret; scan: + VM_WARN_ON(order > 0); spin_unlock(&si->lock); while (++offset <= READ_ONCE(si->highest_bit)) { if (unlikely(--latency_ration < 0)) { @@ -997,38 +1055,6 @@ static int scan_swap_map_slots(struct swap_info_struct *si, return n_ret; } -static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) -{ - unsigned long idx; - struct swap_cluster_info *ci; - unsigned long offset; - - /* - * Should not even be attempting cluster allocations when huge - * page swap is disabled. Warn and fail the allocation. - */ - if (!IS_ENABLED(CONFIG_THP_SWAP)) { - VM_WARN_ON_ONCE(1); - return 0; - } - - if (cluster_list_empty(&si->free_clusters)) - return 0; - - idx = cluster_list_first(&si->free_clusters); - offset = idx * SWAPFILE_CLUSTER; - ci = lock_cluster(si, offset); - alloc_cluster(si, idx); - cluster_set_count(ci, SWAPFILE_CLUSTER); - - memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER); - unlock_cluster(ci); - swap_range_alloc(si, offset, SWAPFILE_CLUSTER); - *slot = swp_entry(si->type, offset); - - return 1; -} - static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) { unsigned long offset = idx * SWAPFILE_CLUSTER; @@ -1042,17 +1068,15 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) swap_range_free(si, offset, SWAPFILE_CLUSTER); } -int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) +int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order) { - unsigned long size = swap_entry_size(entry_size); + int order = swap_entry_order(entry_order); + unsigned long size = 1 << order; struct swap_info_struct *si, *next; long avail_pgs; int n_ret = 0; int node; - /* Only single cluster request supported */ - WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); - spin_lock(&swap_avail_lock); avail_pgs = atomic_long_read(&nr_swap_pages) / size; @@ -1088,14 +1112,10 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) spin_unlock(&si->lock); goto nextsi; } - if (size == SWAPFILE_CLUSTER) { - if (si->flags & SWP_BLKDEV) - n_ret = swap_alloc_cluster(si, swp_entries); - } else - n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, - n_goal, swp_entries); + n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, + n_goal, swp_entries, order); spin_unlock(&si->lock); - if (n_ret || size == SWAPFILE_CLUSTER) + if (n_ret || size > 1) goto check_out; cond_resched(); @@ -1349,7 +1369,7 @@ void put_swap_folio(struct folio *folio, swp_entry_t entry) unsigned char *map; unsigned int i, free_entries = 0; unsigned char val; - int size = swap_entry_size(folio_nr_pages(folio)); + int size = 1 << swap_entry_order(folio_order(folio)); si = _swap_info_get(entry); if (!si) @@ -1647,7 +1667,7 @@ swp_entry_t get_swap_page_of_type(int type) /* This is called for allocating swap entry, not cache */ spin_lock(&si->lock); - if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry)) + if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry, 0)) atomic_long_dec(&nr_swap_pages); spin_unlock(&si->lock); fail: @@ -3101,7 +3121,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) p->flags |= SWP_SYNCHRONOUS_IO; if (p->bdev && bdev_nonrot(p->bdev)) { - int cpu; + int cpu, i; unsigned long ci, nr_cluster; p->flags |= SWP_SOLIDSTATE; @@ -3139,7 +3159,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) struct percpu_cluster *cluster; cluster = per_cpu_ptr(p->percpu_cluster, cpu); - cluster->next = SWAP_NEXT_INVALID; + for (i = 0; i < SWAP_NR_ORDERS; i++) + cluster->next[i] = SWAP_NEXT_INVALID; } } else { atomic_inc(&nr_rotate_swap); From patchwork Wed Mar 27 14:45:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13606753 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84001C54E67 for ; Wed, 27 Mar 2024 14:46:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 97EF26B00A3; Wed, 27 Mar 2024 10:46:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 907406B00A4; Wed, 27 Mar 2024 10:46:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 75D496B00A5; Wed, 27 Mar 2024 10:46:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 52FC06B00A3 for ; 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Wed, 27 Mar 2024 07:45:56 -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, Barry Song Subject: [PATCH v5 5/6] mm: vmscan: Avoid split during shrink_folio_list() Date: Wed, 27 Mar 2024 14:45:36 +0000 Message-Id: <20240327144537.4165578-6-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 4FBC714000D X-Stat-Signature: 43mtg1wwxm7wo7eaxwmyzk7pb1ggidde X-HE-Tag: 1711550759-393876 X-HE-Meta: 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 RwjXLyH3 8rM1iqaXeu2MvjfgWKcUdDH8y7WzLox/qHBOG2aDPMDaDwRaQfat9+2ks20oOJjr1ZvHTHpxG9cRAE031pFDQ5KFQOjKyZ7w9hVlHnMDBUw+qcVL4akxTniXjPaBG3GrbAVe8Cb3Z1laXMT68WfnJuc47+OCPA4JuMrJl2Bn1wTpFG0VWtsFCg6j2BoRg7tApbrSTbyRgqGiLYNpmx3g/+Dvqeh04ENBIehtQR/p0Kxxhoxa4+6WBHH52PNHPWTZuTWJyEt1TrP59c7rThWsfFLL3O8f6G59hwMH+ 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: Now that swap supports storing all mTHP sizes, avoid splitting large folios before swap-out. This benefits performance of the swap-out path by eliding split_folio_to_list(), which is expensive, and also sets us up for swapping in large folios in a future series. If the folio is partially mapped, we continue to split it since we want to avoid the extra IO overhead and storage of writing out pages uneccessarily. Reviewed-by: David Hildenbrand Reviewed-by: Barry Song Signed-off-by: Ryan Roberts --- mm/vmscan.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 00adaf1cb2c3..293120fe54f3 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1223,11 +1223,12 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, if (!can_split_folio(folio, NULL)) goto activate_locked; /* - * Split folios without a PMD map right - * away. Chances are some or all of the - * tail pages can be freed without IO. + * Split partially mapped folios right + * away. We can free the unmapped pages + * without IO. */ - if (!folio_entire_mapcount(folio) && + if (data_race(!list_empty( + &folio->_deferred_list)) && split_folio_to_list(folio, folio_list)) goto activate_locked; From patchwork Wed Mar 27 14:45:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13606754 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BECD2CD1284 for ; Wed, 27 Mar 2024 14:46:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1B8D56B00A4; Wed, 27 Mar 2024 10:46:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 142006B00A5; Wed, 27 Mar 2024 10:46:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E86F26B00A6; 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Wed, 27 Mar 2024 07:45:59 -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, Barry Song Subject: [PATCH v5 6/6] mm: madvise: Avoid split during MADV_PAGEOUT and MADV_COLD Date: Wed, 27 Mar 2024 14:45:37 +0000 Message-Id: <20240327144537.4165578-7-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240327144537.4165578-1-ryan.roberts@arm.com> References: <20240327144537.4165578-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: C91DD160012 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: z73u4uu4m7k4d746hmxynq7n8hu3dmxs X-HE-Tag: 1711550761-974932 X-HE-Meta: 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 mbRAR3Cy jO1E+5Rs4n+yAM4fEwg9A974ysYE1wQ11Wfyqes0u78TM2x2noq84NQfnQD8h4pPhN9h/yWZTSn6bt+7CEab6Frn5D3PDS/pT98JKUzbyMbo6hPX8KysLyY6uGOmiDZxxOWA4d18CBvuJ0X5aU15CjDXzhRMiCirZw4XCBx1QZUyRdtzuCW7t+ywfroLwzl8mN5PgyQthuBoZkMDd2DQMMrgu69dWR2FALmOPPDmbzWPPhUrw38M0vKI99lO5DuF2T110UCidnKQMTac= 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: Rework madvise_cold_or_pageout_pte_range() to avoid splitting any large folio that is fully and contiguously mapped in the pageout/cold vm range. This change means that large folios will be maintained all the way to swap storage. This both improves performance during swap-out, by eliding the cost of splitting the folio, and sets us up nicely for maintaining the large folio when it is swapped back in (to be covered in a separate series). Folios that are not fully mapped in the target range are still split, but note that behavior is changed so that if the split fails for any reason (folio locked, shared, etc) we now leave it as is and move to the next pte in the range and continue work on the proceeding folios. Previously any failure of this sort would cause the entire operation to give up and no folios mapped at higher addresses were paged out or made cold. Given large folios are becoming more common, this old behavior would have likely lead to wasted opportunities. While we are at it, change the code that clears young from the ptes to use ptep_test_and_clear_young(), via the new mkold_ptes() batch helper function. This is more efficent than get_and_clear/modify/set, especially for contpte mappings on arm64, where the old approach would require unfolding/refolding and the new approach can be done in place. Reviewed-by: Barry Song Signed-off-by: Ryan Roberts --- include/linux/pgtable.h | 30 ++++++++++++++ mm/internal.h | 12 +++++- mm/madvise.c | 88 ++++++++++++++++++++++++----------------- mm/memory.c | 4 +- 4 files changed, 93 insertions(+), 41 deletions(-) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 8185939df1e8..391f56a1b188 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -361,6 +361,36 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, } #endif +#ifndef mkold_ptes +/** + * mkold_ptes - Mark PTEs that map consecutive pages of the same folio as old. + * @vma: VMA the pages are mapped into. + * @addr: Address the first page is mapped at. + * @ptep: Page table pointer for the first entry. + * @nr: Number of entries to mark old. + * + * May be overridden by the architecture; otherwise, implemented as a simple + * loop over ptep_test_and_clear_young(). + * + * Note that PTE bits in the PTE range besides the PFN can differ. For example, + * some PTEs might be write-protected. + * + * Context: The caller holds the page table lock. The PTEs map consecutive + * pages that belong to the same folio. The PTEs are all in the same PMD. + */ +static inline void mkold_ptes(struct vm_area_struct *vma, unsigned long addr, + pte_t *ptep, unsigned int nr) +{ + for (;;) { + ptep_test_and_clear_young(vma, addr, ptep); + if (--nr == 0) + break; + ptep++; + addr += PAGE_SIZE; + } +} +#endif + #ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG) static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, diff --git a/mm/internal.h b/mm/internal.h index eadb79c3a357..efee8e4cd2af 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -130,6 +130,8 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) * @flags: Flags to modify the PTE batch semantics. * @any_writable: Optional pointer to indicate whether any entry except the * first one is writable. + * @any_young: Optional pointer to indicate whether any entry except the + * first one is young. * * Detect a PTE batch: consecutive (present) PTEs that map consecutive * pages of the same large folio. @@ -145,16 +147,18 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) */ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, - bool *any_writable) + bool *any_writable, bool *any_young) { unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio); const pte_t *end_ptep = start_ptep + max_nr; pte_t expected_pte, *ptep; - bool writable; + bool writable, young; int nr; if (any_writable) *any_writable = false; + if (any_young) + *any_young = false; VM_WARN_ON_FOLIO(!pte_present(pte), folio); VM_WARN_ON_FOLIO(!folio_test_large(folio) || max_nr < 1, folio); @@ -168,6 +172,8 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, pte = ptep_get(ptep); if (any_writable) writable = !!pte_write(pte); + if (any_young) + young = !!pte_young(pte); pte = __pte_batch_clear_ignored(pte, flags); if (!pte_same(pte, expected_pte)) @@ -183,6 +189,8 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr, if (any_writable) *any_writable |= writable; + if (any_young) + *any_young |= young; nr = pte_batch_hint(ptep, pte); expected_pte = pte_advance_pfn(expected_pte, nr); diff --git a/mm/madvise.c b/mm/madvise.c index 070bedb4996e..bd00b83e7c50 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -336,6 +336,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, LIST_HEAD(folio_list); bool pageout_anon_only_filter; unsigned int batch_count = 0; + int nr; if (fatal_signal_pending(current)) return -EINTR; @@ -423,7 +424,8 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, return 0; flush_tlb_batched_pending(mm); arch_enter_lazy_mmu_mode(); - for (; addr < end; pte++, addr += PAGE_SIZE) { + for (; addr < end; pte += nr, addr += nr * PAGE_SIZE) { + nr = 1; ptent = ptep_get(pte); if (++batch_count == SWAP_CLUSTER_MAX) { @@ -447,55 +449,67 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, continue; /* - * Creating a THP page is expensive so split it only if we - * are sure it's worth. Split it if we are only owner. + * If we encounter a large folio, only split it if it is not + * fully mapped within the range we are operating on. Otherwise + * leave it as is so that it can be swapped out whole. If we + * fail to split a folio, leave it in place and advance to the + * next pte in the range. */ if (folio_test_large(folio)) { - int err; - - if (folio_likely_mapped_shared(folio)) - break; - if (pageout_anon_only_filter && !folio_test_anon(folio)) - break; - if (!folio_trylock(folio)) - break; - folio_get(folio); - arch_leave_lazy_mmu_mode(); - pte_unmap_unlock(start_pte, ptl); - start_pte = NULL; - err = split_folio(folio); - folio_unlock(folio); - folio_put(folio); - if (err) - break; - start_pte = pte = - pte_offset_map_lock(mm, pmd, addr, &ptl); - if (!start_pte) - break; - arch_enter_lazy_mmu_mode(); - pte--; - addr -= PAGE_SIZE; - continue; + const fpb_t fpb_flags = FPB_IGNORE_DIRTY | + FPB_IGNORE_SOFT_DIRTY; + int max_nr = (end - addr) / PAGE_SIZE; + bool any_young; + + nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, + fpb_flags, NULL, &any_young); + if (any_young) + ptent = pte_mkyoung(ptent); + + if (nr < folio_nr_pages(folio)) { + int err; + + if (folio_likely_mapped_shared(folio)) + continue; + if (pageout_anon_only_filter && !folio_test_anon(folio)) + continue; + if (!folio_trylock(folio)) + continue; + folio_get(folio); + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(start_pte, ptl); + start_pte = NULL; + err = split_folio(folio); + folio_unlock(folio); + folio_put(folio); + if (err) + continue; + start_pte = pte = + pte_offset_map_lock(mm, pmd, addr, &ptl); + if (!start_pte) + break; + arch_enter_lazy_mmu_mode(); + nr = 0; + continue; + } } /* * Do not interfere with other mappings of this folio and - * non-LRU folio. + * non-LRU folio. If we have a large folio at this point, we + * know it is fully mapped so if its mapcount is the same as its + * number of pages, it must be exclusive. */ - if (!folio_test_lru(folio) || folio_mapcount(folio) != 1) + if (!folio_test_lru(folio) || + folio_mapcount(folio) != folio_nr_pages(folio)) continue; if (pageout_anon_only_filter && !folio_test_anon(folio)) continue; - VM_BUG_ON_FOLIO(folio_test_large(folio), folio); - if (!pageout && pte_young(ptent)) { - ptent = ptep_get_and_clear_full(mm, addr, pte, - tlb->fullmm); - ptent = pte_mkold(ptent); - set_pte_at(mm, addr, pte, ptent); - tlb_remove_tlb_entry(tlb, pte, addr); + mkold_ptes(vma, addr, pte, nr); + tlb_remove_tlb_entries(tlb, pte, nr, addr); } /* diff --git a/mm/memory.c b/mm/memory.c index 9d844582ba38..b5b48f4cf2af 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -989,7 +989,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma flags |= FPB_IGNORE_SOFT_DIRTY; nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags, - &any_writable); + &any_writable, NULL); folio_ref_add(folio, nr); if (folio_test_anon(folio)) { if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page, @@ -1553,7 +1553,7 @@ static inline int zap_present_ptes(struct mmu_gather *tlb, */ if (unlikely(folio_test_large(folio) && max_nr != 1)) { nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, fpb_flags, - NULL); + NULL, NULL); zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr, addr, details, rss, force_flush,