From cd39d4e9e71c5437b67c819c3d53032145bf2879 Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:47:09 -0700 Subject: mm: hugetlb: gather discrete indexes of tail page For HugeTLB page, there are more metadata to save in the struct page. But the head struct page cannot meet our needs, so we have to abuse other tail struct page to store the metadata. In order to avoid conflicts caused by subsequent use of more tail struct pages, we can gather these discrete indexes of tail struct page. In this case, it will be easier to add a new tail page index later. Link: https://lkml.kernel.org/r/20210510030027.56044-4-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Oscar Salvador Reviewed-by: Miaohe Lin Tested-by: Chen Huang Tested-by: Bodeddula Balasubramaniam Acked-by: Michal Hocko Reviewed-by: Mike Kravetz Cc: Alexander Viro Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Balbir Singh Cc: Barry Song Cc: Borislav Petkov Cc: Dave Hansen Cc: David Hildenbrand Cc: David Rientjes Cc: HORIGUCHI NAOYA Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joao Martins Cc: Joerg Roedel Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Mina Almasry Cc: Oliver Neukum Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 3c0117656745..0c8c96481259 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -29,6 +29,23 @@ typedef struct { unsigned long pd; } hugepd_t; #include #include +/* + * For HugeTLB page, there are more metadata to save in the struct page. But + * the head struct page cannot meet our needs, so we have to abuse other tail + * struct page to store the metadata. In order to avoid conflicts caused by + * subsequent use of more tail struct pages, we gather these discrete indexes + * of tail struct page here. + */ +enum { + SUBPAGE_INDEX_SUBPOOL = 1, /* reuse page->private */ +#ifdef CONFIG_CGROUP_HUGETLB + SUBPAGE_INDEX_CGROUP, /* reuse page->private */ + SUBPAGE_INDEX_CGROUP_RSVD, /* reuse page->private */ + __MAX_CGROUP_SUBPAGE_INDEX = SUBPAGE_INDEX_CGROUP_RSVD, +#endif + __NR_USED_SUBPAGE, +}; + struct hugepage_subpool { spinlock_t lock; long count; @@ -635,13 +652,13 @@ extern unsigned int default_hstate_idx; */ static inline struct hugepage_subpool *hugetlb_page_subpool(struct page *hpage) { - return (struct hugepage_subpool *)(hpage+1)->private; + return (void *)page_private(hpage + SUBPAGE_INDEX_SUBPOOL); } static inline void hugetlb_set_page_subpool(struct page *hpage, struct hugepage_subpool *subpool) { - set_page_private(hpage+1, (unsigned long)subpool); + set_page_private(hpage + SUBPAGE_INDEX_SUBPOOL, (unsigned long)subpool); } static inline struct hstate *hstate_file(struct file *f) -- cgit v1.2.3 From ad2fa3717b74994a22519dbe045757135db00dbb Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:47:21 -0700 Subject: mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.com Signed-off-by: Muchun Song Signed-off-by: Mike Kravetz Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Mike Kravetz Reviewed-by: Oscar Salvador Cc: Alexander Viro Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Balbir Singh Cc: Barry Song Cc: Bodeddula Balasubramaniam Cc: Borislav Petkov Cc: Chen Huang Cc: Dave Hansen Cc: David Hildenbrand Cc: David Rientjes Cc: HORIGUCHI NAOYA Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joao Martins Cc: Joerg Roedel Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Michal Hocko Cc: Mina Almasry Cc: Oliver Neukum Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/admin-guide/mm/hugetlbpage.rst | 8 ++ Documentation/admin-guide/mm/memory-hotplug.rst | 13 ++++ include/linux/hugetlb.h | 3 + include/linux/mm.h | 2 + mm/hugetlb.c | 98 +++++++++++++++++++++---- mm/hugetlb_vmemmap.c | 34 +++++++++ mm/hugetlb_vmemmap.h | 6 ++ mm/migrate.c | 5 +- mm/sparse-vmemmap.c | 75 ++++++++++++++++++- 9 files changed, 227 insertions(+), 17 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index f7b1c7462991..6988895d09a8 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -60,6 +60,10 @@ HugePages_Surp the pool above the value in ``/proc/sys/vm/nr_hugepages``. The maximum number of surplus huge pages is controlled by ``/proc/sys/vm/nr_overcommit_hugepages``. + Note: When the feature of freeing unused vmemmap pages associated + with each hugetlb page is enabled, the number of surplus huge pages + may be temporarily larger than the maximum number of surplus huge + pages when the system is under memory pressure. Hugepagesize is the default hugepage size (in Kb). Hugetlb @@ -80,6 +84,10 @@ returned to the huge page pool when freed by a task. A user with root privileges can dynamically allocate more or free some persistent huge pages by increasing or decreasing the value of ``nr_hugepages``. +Note: When the feature of freeing unused vmemmap pages associated with each +hugetlb page is enabled, we can fail to free the huge pages triggered by +the user when ths system is under memory pressure. Please try again later. + Pages that are used as huge pages are reserved inside the kernel and cannot be used for other purposes. Huge pages cannot be swapped out under memory pressure. diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst index 05d51d2d8beb..c6bae2d77160 100644 --- a/Documentation/admin-guide/mm/memory-hotplug.rst +++ b/Documentation/admin-guide/mm/memory-hotplug.rst @@ -357,6 +357,19 @@ creates ZONE_MOVABLE as following. Unfortunately, there is no information to show which memory block belongs to ZONE_MOVABLE. This is TBD. + Memory offlining can fail when dissolving a free huge page on ZONE_MOVABLE + and the feature of freeing unused vmemmap pages associated with each hugetlb + page is enabled. + + This can happen when we have plenty of ZONE_MOVABLE memory, but not enough + kernel memory to allocate vmemmmap pages. We may even be able to migrate + huge page contents, but will not be able to dissolve the source huge page. + This will prevent an offline operation and is unfortunate as memory offlining + is expected to succeed on movable zones. Users that depend on memory hotplug + to succeed for movable zones should carefully consider whether the memory + savings gained from this feature are worth the risk of possibly not being + able to offline memory in certain situations. + .. note:: Techniques that rely on long-term pinnings of memory (especially, RDMA and vfio) are fundamentally problematic with ZONE_MOVABLE and, therefore, memory diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 0c8c96481259..3578d9d708fe 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -532,12 +532,14 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, * modifications require hugetlb_lock. * HPG_freed - Set when page is on the free lists. * Synchronization: hugetlb_lock held for examination and modification. + * HPG_vmemmap_optimized - Set when the vmemmap pages of the page are freed. */ enum hugetlb_page_flags { HPG_restore_reserve = 0, HPG_migratable, HPG_temporary, HPG_freed, + HPG_vmemmap_optimized, __NR_HPAGEFLAGS, }; @@ -583,6 +585,7 @@ HPAGEFLAG(RestoreReserve, restore_reserve) HPAGEFLAG(Migratable, migratable) HPAGEFLAG(Temporary, temporary) HPAGEFLAG(Freed, freed) +HPAGEFLAG(VmemmapOptimized, vmemmap_optimized) #ifdef CONFIG_HUGETLB_PAGE diff --git a/include/linux/mm.h b/include/linux/mm.h index 3437aa7c6c91..706bee98d965 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3078,6 +3078,8 @@ static inline void print_vma_addr(char *prefix, unsigned long rip) void vmemmap_remap_free(unsigned long start, unsigned long end, unsigned long reuse); +int vmemmap_remap_alloc(unsigned long start, unsigned long end, + unsigned long reuse, gfp_t gfp_mask); void *sparse_buffer_alloc(unsigned long size); struct page * __populate_section_memmap(unsigned long pfn, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index e7eb1ab8c78a..778db5de6232 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1376,6 +1376,39 @@ static void remove_hugetlb_page(struct hstate *h, struct page *page, h->nr_huge_pages_node[nid]--; } +static void add_hugetlb_page(struct hstate *h, struct page *page, + bool adjust_surplus) +{ + int zeroed; + int nid = page_to_nid(page); + + VM_BUG_ON_PAGE(!HPageVmemmapOptimized(page), page); + + lockdep_assert_held(&hugetlb_lock); + + INIT_LIST_HEAD(&page->lru); + h->nr_huge_pages++; + h->nr_huge_pages_node[nid]++; + + if (adjust_surplus) { + h->surplus_huge_pages++; + h->surplus_huge_pages_node[nid]++; + } + + set_compound_page_dtor(page, HUGETLB_PAGE_DTOR); + set_page_private(page, 0); + SetHPageVmemmapOptimized(page); + + /* + * This page is now managed by the hugetlb allocator and has + * no users -- drop the last reference. + */ + zeroed = put_page_testzero(page); + VM_BUG_ON_PAGE(!zeroed, page); + arch_clear_hugepage_flags(page); + enqueue_huge_page(h, page); +} + static void __update_and_free_page(struct hstate *h, struct page *page) { int i; @@ -1384,6 +1417,18 @@ static void __update_and_free_page(struct hstate *h, struct page *page) if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) return; + if (alloc_huge_page_vmemmap(h, page)) { + spin_lock_irq(&hugetlb_lock); + /* + * If we cannot allocate vmemmap pages, just refuse to free the + * page and put the page back on the hugetlb free list and treat + * as a surplus page. + */ + add_hugetlb_page(h, page, true); + spin_unlock_irq(&hugetlb_lock); + return; + } + for (i = 0; i < pages_per_huge_page(h); i++, subpage = mem_map_next(subpage, page, i)) { subpage->flags &= ~(1 << PG_locked | 1 << PG_error | @@ -1450,7 +1495,7 @@ static inline void flush_free_hpage_work(struct hstate *h) static void update_and_free_page(struct hstate *h, struct page *page, bool atomic) { - if (!free_vmemmap_pages_per_hpage(h) || !atomic) { + if (!HPageVmemmapOptimized(page) || !atomic) { __update_and_free_page(h, page); return; } @@ -1806,10 +1851,14 @@ static struct page *remove_pool_huge_page(struct hstate *h, * nothing for in-use hugepages and non-hugepages. * This function returns values like below: * - * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use - * (allocated or reserved.) - * 0: successfully dissolved free hugepages or the page is not a - * hugepage (considered as already dissolved) + * -ENOMEM: failed to allocate vmemmap pages to free the freed hugepages + * when the system is under memory pressure and the feature of + * freeing unused vmemmap pages associated with each hugetlb page + * is enabled. + * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use + * (allocated or reserved.) + * 0: successfully dissolved free hugepages or the page is not a + * hugepage (considered as already dissolved) */ int dissolve_free_huge_page(struct page *page) { @@ -1851,19 +1900,38 @@ retry: goto retry; } - /* - * Move PageHWPoison flag from head page to the raw error page, - * which makes any subpages rather than the error page reusable. - */ - if (PageHWPoison(head) && page != head) { - SetPageHWPoison(page); - ClearPageHWPoison(head); - } remove_hugetlb_page(h, head, false); h->max_huge_pages--; spin_unlock_irq(&hugetlb_lock); - update_and_free_page(h, head, false); - return 0; + + /* + * Normally update_and_free_page will allocate required vmemmmap + * before freeing the page. update_and_free_page will fail to + * free the page if it can not allocate required vmemmap. We + * need to adjust max_huge_pages if the page is not freed. + * Attempt to allocate vmemmmap here so that we can take + * appropriate action on failure. + */ + rc = alloc_huge_page_vmemmap(h, head); + if (!rc) { + /* + * Move PageHWPoison flag from head page to the raw + * error page, which makes any subpages rather than + * the error page reusable. + */ + if (PageHWPoison(head) && page != head) { + SetPageHWPoison(page); + ClearPageHWPoison(head); + } + update_and_free_page(h, head, false); + } else { + spin_lock_irq(&hugetlb_lock); + add_hugetlb_page(h, head, false); + h->max_huge_pages++; + spin_unlock_irq(&hugetlb_lock); + } + + return rc; } out: spin_unlock_irq(&hugetlb_lock); diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index cb28c5b6c9ff..a897c7778246 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -185,6 +185,38 @@ static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h) return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; } +/* + * Previously discarded vmemmap pages will be allocated and remapping + * after this function returns zero. + */ +int alloc_huge_page_vmemmap(struct hstate *h, struct page *head) +{ + int ret; + unsigned long vmemmap_addr = (unsigned long)head; + unsigned long vmemmap_end, vmemmap_reuse; + + if (!HPageVmemmapOptimized(head)) + return 0; + + vmemmap_addr += RESERVE_VMEMMAP_SIZE; + vmemmap_end = vmemmap_addr + free_vmemmap_pages_size_per_hpage(h); + vmemmap_reuse = vmemmap_addr - PAGE_SIZE; + /* + * The pages which the vmemmap virtual address range [@vmemmap_addr, + * @vmemmap_end) are mapped to are freed to the buddy allocator, and + * the range is mapped to the page which @vmemmap_reuse is mapped to. + * When a HugeTLB page is freed to the buddy allocator, previously + * discarded vmemmap pages must be allocated and remapping. + */ + ret = vmemmap_remap_alloc(vmemmap_addr, vmemmap_end, vmemmap_reuse, + GFP_KERNEL | __GFP_NORETRY | __GFP_THISNODE); + + if (!ret) + ClearHPageVmemmapOptimized(head); + + return ret; +} + void free_huge_page_vmemmap(struct hstate *h, struct page *head) { unsigned long vmemmap_addr = (unsigned long)head; @@ -203,4 +235,6 @@ void free_huge_page_vmemmap(struct hstate *h, struct page *head) * which the range [@vmemmap_addr, @vmemmap_end] is mapped to. */ vmemmap_remap_free(vmemmap_addr, vmemmap_end, vmemmap_reuse); + + SetHPageVmemmapOptimized(head); } diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index 01f8637adbe0..a37771b0b82a 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -11,6 +11,7 @@ #include #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +int alloc_huge_page_vmemmap(struct hstate *h, struct page *head); void free_huge_page_vmemmap(struct hstate *h, struct page *head); /* @@ -25,6 +26,11 @@ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) return 0; } #else +static inline int alloc_huge_page_vmemmap(struct hstate *h, struct page *head) +{ + return 0; +} + static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } diff --git a/mm/migrate.c b/mm/migrate.c index 380ca57b9031..cc4d6af41683 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -626,7 +626,10 @@ void migrate_page_states(struct page *newpage, struct page *page) if (PageSwapCache(page)) ClearPageSwapCache(page); ClearPagePrivate(page); - set_page_private(page, 0); + + /* page->private contains hugetlb specific flags */ + if (!PageHuge(page)) + set_page_private(page, 0); /* * If any waiters have accumulated on the new page then diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 3ec5488c815c..a3aa275e2668 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -40,7 +40,8 @@ * @remap_pte: called for each lowest-level entry (PTE). * @reuse_page: the page which is reused for the tail vmemmap pages. * @reuse_addr: the virtual address of the @reuse_page page. - * @vmemmap_pages: the list head of the vmemmap pages that can be freed. + * @vmemmap_pages: the list head of the vmemmap pages that can be freed + * or is mapped from. */ struct vmemmap_remap_walk { void (*remap_pte)(pte_t *pte, unsigned long addr, @@ -224,6 +225,78 @@ void vmemmap_remap_free(unsigned long start, unsigned long end, free_vmemmap_page_list(&vmemmap_pages); } +static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, + struct vmemmap_remap_walk *walk) +{ + pgprot_t pgprot = PAGE_KERNEL; + struct page *page; + void *to; + + BUG_ON(pte_page(*pte) != walk->reuse_page); + + page = list_first_entry(walk->vmemmap_pages, struct page, lru); + list_del(&page->lru); + to = page_to_virt(page); + copy_page(to, (void *)walk->reuse_addr); + + set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot)); +} + +static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, + gfp_t gfp_mask, struct list_head *list) +{ + unsigned long nr_pages = (end - start) >> PAGE_SHIFT; + int nid = page_to_nid((struct page *)start); + struct page *page, *next; + + while (nr_pages--) { + page = alloc_pages_node(nid, gfp_mask, 0); + if (!page) + goto out; + list_add_tail(&page->lru, list); + } + + return 0; +out: + list_for_each_entry_safe(page, next, list, lru) + __free_pages(page, 0); + return -ENOMEM; +} + +/** + * vmemmap_remap_alloc - remap the vmemmap virtual address range [@start, end) + * to the page which is from the @vmemmap_pages + * respectively. + * @start: start address of the vmemmap virtual address range that we want + * to remap. + * @end: end address of the vmemmap virtual address range that we want to + * remap. + * @reuse: reuse address. + * @gfp_mask: GFP flag for allocating vmemmap pages. + */ +int vmemmap_remap_alloc(unsigned long start, unsigned long end, + unsigned long reuse, gfp_t gfp_mask) +{ + LIST_HEAD(vmemmap_pages); + struct vmemmap_remap_walk walk = { + .remap_pte = vmemmap_restore_pte, + .reuse_addr = reuse, + .vmemmap_pages = &vmemmap_pages, + }; + + /* See the comment in the vmemmap_remap_free(). */ + BUG_ON(start - reuse != PAGE_SIZE); + + might_sleep_if(gfpflags_allow_blocking(gfp_mask)); + + if (alloc_vmemmap_page_list(start, end, gfp_mask, &vmemmap_pages)) + return -ENOMEM; + + vmemmap_remap_range(reuse, end, &walk); + + return 0; +} + /* * Allocate a block of memory to be used to back the virtual memory map * or to back the page tables that are used to create the mapping. -- cgit v1.2.3 From e9fdff87e893ec5b7c32836675db80cf691b2a8b Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:47:25 -0700 Subject: mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap Add a kernel parameter hugetlb_free_vmemmap to enable the feature of freeing unused vmemmap pages associated with each hugetlb page on boot. We disable PMD mapping of vmemmap pages for x86-64 arch when this feature is enabled. Because vmemmap_remap_free() depends on vmemmap being base page mapped. Link: https://lkml.kernel.org/r/20210510030027.56044-8-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Oscar Salvador Reviewed-by: Barry Song Reviewed-by: Miaohe Lin Tested-by: Chen Huang Tested-by: Bodeddula Balasubramaniam Reviewed-by: Mike Kravetz Cc: Alexander Viro Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Balbir Singh Cc: Borislav Petkov Cc: Dave Hansen Cc: David Hildenbrand Cc: David Rientjes Cc: HORIGUCHI NAOYA Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joao Martins Cc: Joerg Roedel Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Michal Hocko Cc: Mina Almasry Cc: Oliver Neukum Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++++ Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ arch/x86/mm/init_64.c | 8 ++++++-- include/linux/hugetlb.h | 19 +++++++++++++++++++ mm/hugetlb_vmemmap.c | 24 ++++++++++++++++++++++++ 5 files changed, 69 insertions(+), 2 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 566c4b9af3cd..b787a9953f2e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1567,6 +1567,23 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + enabled. + Allows heavy hugetlb users to free up some more + memory (6 * PAGE_SIZE for each 2MB hugetlb page). + This feauture is not free though. Large page + tables are not used to back vmemmap pages which + can lead to a performance degradation for some + workloads. Also there will be memory allocation + required when hugetlb pages are freed from the + pool which can lead to corner cases under heavy + memory pressure. + Format: { on | off (default) } + + on: enable the feature + off: disable the feature + hung_task_panic= [KNL] Should the hung task detector generate panics. Format: 0 | 1 diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index 6988895d09a8..8abaeb144e44 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -153,6 +153,9 @@ default_hugepagesz will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. +hugetlb_free_vmemmap + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing + unused vmemmap pages associated with each HugeTLB page. When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` indicates the current number of pre-allocated huge pages of the default size. diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 65ea58527176..9d9d18d0c2a1 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -1609,7 +1610,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE)); VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE)); - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) + if ((is_hugetlb_free_vmemmap_enabled() && !altmap) || + end - start < PAGES_PER_SECTION * sizeof(struct page)) err = vmemmap_populate_basepages(start, end, node, NULL); else if (boot_cpu_has(X86_FEATURE_PSE)) err = vmemmap_populate_hugepages(start, end, node, altmap); @@ -1637,6 +1639,8 @@ void register_page_bootmem_memmap(unsigned long section_nr, pmd_t *pmd; unsigned int nr_pmd_pages; struct page *page; + bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || + is_hugetlb_free_vmemmap_enabled(); for (; addr < end; addr = next) { pte_t *pte = NULL; @@ -1662,7 +1666,7 @@ void register_page_bootmem_memmap(unsigned long section_nr, } get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); - if (!boot_cpu_has(X86_FEATURE_PSE)) { + if (base_mapping) { next = (addr + PAGE_SIZE) & PAGE_MASK; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 3578d9d708fe..9ad99848f9f0 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -892,6 +892,20 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, } #endif +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +extern bool hugetlb_free_vmemmap_enabled; + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return hugetlb_free_vmemmap_enabled; +} +#else +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} +#endif + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; @@ -1046,6 +1060,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr pte_t *ptep, pte_t pte, unsigned long sz) { } + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} #endif /* CONFIG_HUGETLB_PAGE */ static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index a897c7778246..3070e1465b1b 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -168,6 +168,8 @@ * (last) level. So this type of HugeTLB page can be optimized only when its * size of the struct page structs is greater than 2 pages. */ +#define pr_fmt(fmt) "HugeTLB: " fmt + #include "hugetlb_vmemmap.h" /* @@ -180,6 +182,28 @@ #define RESERVE_VMEMMAP_NR 2U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) +bool hugetlb_free_vmemmap_enabled; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + /* We cannot optimize if a "struct page" crosses page boundaries. */ + if ((!is_power_of_2(sizeof(struct page)))) { + pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n"); + return 0; + } + + if (!buf) + return -EINVAL; + + if (!strcmp(buf, "on")) + hugetlb_free_vmemmap_enabled = true; + else if (strcmp(buf, "off")) + return -EINVAL; + + return 0; +} +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); + static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h) { return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; -- cgit v1.2.3 From 774905878fc9b0b9a5ee4a889b97f773a077aeee Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:47:33 -0700 Subject: mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate All the infrastructure is ready, so we introduce nr_free_vmemmap_pages field in the hstate to indicate how many vmemmap pages associated with a HugeTLB page that can be freed to buddy allocator. And initialize it in the hugetlb_vmemmap_init(). This patch is actual enablement of the feature. There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct page structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so add a BUILD_BUG_ON to catch invalid usage of the tail struct page. Link: https://lkml.kernel.org/r/20210510030027.56044-10-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Kravetz Reviewed-by: Oscar Salvador Reviewed-by: Miaohe Lin Tested-by: Chen Huang Tested-by: Bodeddula Balasubramaniam Cc: Alexander Viro Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Balbir Singh Cc: Barry Song Cc: Borislav Petkov Cc: Dave Hansen Cc: David Hildenbrand Cc: David Rientjes Cc: HORIGUCHI NAOYA Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Joao Martins Cc: Joerg Roedel Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Michal Hocko Cc: Mina Almasry Cc: Oliver Neukum Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 3 +++ mm/hugetlb.c | 1 + mm/hugetlb_vmemmap.c | 33 +++++++++++++++++++++++++++++++++ mm/hugetlb_vmemmap.h | 10 ++++++---- 4 files changed, 43 insertions(+), 4 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 9ad99848f9f0..8c1920844236 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -608,6 +608,9 @@ struct hstate { unsigned int nr_huge_pages_node[MAX_NUMNODES]; unsigned int free_huge_pages_node[MAX_NUMNODES]; unsigned int surplus_huge_pages_node[MAX_NUMNODES]; +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + unsigned int nr_free_vmemmap_pages; +#endif #ifdef CONFIG_CGROUP_HUGETLB /* cgroup control files */ struct cftype cgroup_files_dfl[7]; diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 778db5de6232..dd9c90c082fc 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3585,6 +3585,7 @@ void __init hugetlb_add_hstate(unsigned int order) h->next_nid_to_free = first_memory_node; snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", huge_page_size(h)/1024); + hugetlb_vmemmap_init(h); parsed_hstate = h; } diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 3070e1465b1b..f9f9bb212319 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -262,3 +262,36 @@ void free_huge_page_vmemmap(struct hstate *h, struct page *head) SetHPageVmemmapOptimized(head); } + +void __init hugetlb_vmemmap_init(struct hstate *h) +{ + unsigned int nr_pages = pages_per_huge_page(h); + unsigned int vmemmap_pages; + + /* + * There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct + * page structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, + * so add a BUILD_BUG_ON to catch invalid usage of the tail struct page. + */ + BUILD_BUG_ON(__NR_USED_SUBPAGE >= + RESERVE_VMEMMAP_SIZE / sizeof(struct page)); + + if (!hugetlb_free_vmemmap_enabled) + return; + + vmemmap_pages = (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; + /* + * The head page and the first tail page are not to be freed to buddy + * allocator, the other pages will map to the first tail page, so they + * can be freed. + * + * Could RESERVE_VMEMMAP_NR be greater than @vmemmap_pages? It is true + * on some architectures (e.g. aarch64). See Documentation/arm64/ + * hugetlbpage.rst for more details. + */ + if (likely(vmemmap_pages > RESERVE_VMEMMAP_NR)) + h->nr_free_vmemmap_pages = vmemmap_pages - RESERVE_VMEMMAP_NR; + + pr_info("can free %d vmemmap pages for %s\n", h->nr_free_vmemmap_pages, + h->name); +} diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index a37771b0b82a..cb2bef8f9e73 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -13,17 +13,15 @@ #ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP int alloc_huge_page_vmemmap(struct hstate *h, struct page *head); void free_huge_page_vmemmap(struct hstate *h, struct page *head); +void hugetlb_vmemmap_init(struct hstate *h); /* * How many vmemmap pages associated with a HugeTLB page that can be freed * to the buddy allocator. - * - * Todo: Returns zero for now, which means the feature is disabled. We will - * enable it once all the infrastructure is there. */ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { - return 0; + return h->nr_free_vmemmap_pages; } #else static inline int alloc_huge_page_vmemmap(struct hstate *h, struct page *head) @@ -35,6 +33,10 @@ static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head) { } +static inline void hugetlb_vmemmap_init(struct hstate *h) +{ +} + static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { return 0; -- cgit v1.2.3 From 79c1c594f49a88fba9744cb5c85978c6b1b365ec Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 30 Jun 2021 18:48:00 -0700 Subject: mm/hugetlb: change parameters of arch_make_huge_pte() Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu Signed-off-by: Christophe Leroy Acked-by: Mike Kravetz Cc: Nicholas Piggin Cc: Mike Kravetz Cc: Mike Rapoport Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Uladzislau Rezki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm64/include/asm/hugetlb.h | 3 +-- arch/arm64/mm/hugetlbpage.c | 5 ++--- arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h | 5 ++--- arch/sparc/include/asm/pgtable_64.h | 3 +-- arch/sparc/mm/hugetlbpage.c | 6 ++---- include/linux/hugetlb.h | 4 ++-- mm/hugetlb.c | 6 ++++-- mm/migrate.c | 4 +++- 8 files changed, 17 insertions(+), 19 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h index 5abf91e3494c..1242f71937f8 100644 --- a/arch/arm64/include/asm/hugetlb.h +++ b/arch/arm64/include/asm/hugetlb.h @@ -23,8 +23,7 @@ static inline void arch_clear_hugepage_flags(struct page *page) } #define arch_clear_hugepage_flags arch_clear_hugepage_flags -extern pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writable); +pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags); #define arch_make_huge_pte arch_make_huge_pte #define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT extern void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 58987a98e179..23505fc35324 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -339,10 +339,9 @@ pte_t *huge_pte_offset(struct mm_struct *mm, return NULL; } -pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writable) +pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags) { - size_t pagesize = huge_page_size(hstate_vma(vma)); + size_t pagesize = 1UL << shift; if (pagesize == CONT_PTE_SIZE) { entry = pte_mkcont(entry); diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h index 39be9aea86db..64b6c608eca4 100644 --- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h @@ -66,10 +66,9 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm, } #ifdef CONFIG_PPC_4K_PAGES -static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writable) +static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags) { - size_t size = huge_page_size(hstate_vma(vma)); + size_t size = 1UL << shift; if (size == SZ_16K) return __pte(pte_val(entry) & ~_PAGE_HUGE); diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h index 550d3904de65..2cd80a0a9795 100644 --- a/arch/sparc/include/asm/pgtable_64.h +++ b/arch/sparc/include/asm/pgtable_64.h @@ -377,8 +377,7 @@ static inline pgprot_t pgprot_noncached(pgprot_t prot) #define pgprot_noncached pgprot_noncached #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) -extern pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writable); +pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags); #define arch_make_huge_pte arch_make_huge_pte static inline unsigned long __pte_default_huge_mask(void) { diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c index 04d8790f6c32..0f49fada2093 100644 --- a/arch/sparc/mm/hugetlbpage.c +++ b/arch/sparc/mm/hugetlbpage.c @@ -177,10 +177,8 @@ static pte_t hugepage_shift_to_tte(pte_t entry, unsigned int shift) return sun4u_hugepage_shift_to_tte(entry, shift); } -pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writeable) +pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags) { - unsigned int shift = huge_page_shift(hstate_vma(vma)); pte_t pte; pte = hugepage_shift_to_tte(entry, shift); @@ -188,7 +186,7 @@ pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, #ifdef CONFIG_SPARC64 /* If this vma has ADI enabled on it, turn on TTE.mcd */ - if (vma->vm_flags & VM_SPARC_ADI) + if (flags & VM_SPARC_ADI) return pte_mkmcd(pte); else return pte_mknotmcd(pte); diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8c1920844236..cfde3bec2261 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -741,8 +741,8 @@ static inline void arch_clear_hugepage_flags(struct page *page) { } #endif #ifndef arch_make_huge_pte -static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, - struct page *page, int writable) +static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, + vm_flags_t flags) { return entry; } diff --git a/mm/hugetlb.c b/mm/hugetlb.c index dd9c90c082fc..88f2178ad7c9 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4060,6 +4060,7 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, int writable) { pte_t entry; + unsigned int shift = huge_page_shift(hstate_vma(vma)); if (writable) { entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page, @@ -4070,7 +4071,7 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, } entry = pte_mkyoung(entry); entry = pte_mkhuge(entry); - entry = arch_make_huge_pte(entry, vma, page, writable); + entry = arch_make_huge_pte(entry, shift, vma->vm_flags); return entry; } @@ -5468,10 +5469,11 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, } if (!huge_pte_none(pte)) { pte_t old_pte; + unsigned int shift = huge_page_shift(hstate_vma(vma)); old_pte = huge_ptep_modify_prot_start(vma, address, ptep); pte = pte_mkhuge(huge_pte_modify(old_pte, newprot)); - pte = arch_make_huge_pte(pte, vma, NULL, 0); + pte = arch_make_huge_pte(pte, shift, vma->vm_flags); huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte); pages++; } diff --git a/mm/migrate.c b/mm/migrate.c index cc4d6af41683..75a15f0a2698 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -226,8 +226,10 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, #ifdef CONFIG_HUGETLB_PAGE if (PageHuge(new)) { + unsigned int shift = huge_page_shift(hstate_vma(vma)); + pte = pte_mkhuge(pte); - pte = arch_make_huge_pte(pte, vma, new, 0); + pte = arch_make_huge_pte(pte, shift, vma->vm_flags); set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); if (PageAnon(new)) hugepage_add_anon_rmap(new, vma, pvmw.address); -- cgit v1.2.3 From 2d7a21715f25122779e2bed17db8c57aa01e922f Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:48:25 -0700 Subject: mm: sparsemem: use huge PMD mapping for vmemmap pages The preparation of splitting huge PMD mapping of vmemmap pages is ready, so switch the mapping from PTE to PMD. Link: https://lkml.kernel.org/r/20210616094915.34432-3-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Cc: Chen Huang Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Michal Hocko Cc: Oscar Salvador Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/admin-guide/kernel-parameters.txt | 7 ------- arch/x86/mm/init_64.c | 8 ++------ include/linux/hugetlb.h | 25 ++++++------------------- mm/memory_hotplug.c | 2 +- 4 files changed, 9 insertions(+), 33 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 597572ceb8ba..7a7da02b3bc6 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1572,13 +1572,6 @@ enabled. Allows heavy hugetlb users to free up some more memory (6 * PAGE_SIZE for each 2MB hugetlb page). - This feauture is not free though. Large page - tables are not used to back vmemmap pages which - can lead to a performance degradation for some - workloads. Also there will be memory allocation - required when hugetlb pages are freed from the - pool which can lead to corner cases under heavy - memory pressure. Format: { on | off (default) } on: enable the feature diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 9d9d18d0c2a1..65ea58527176 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -34,7 +34,6 @@ #include #include #include -#include #include #include @@ -1610,8 +1609,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE)); VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE)); - if ((is_hugetlb_free_vmemmap_enabled() && !altmap) || - end - start < PAGES_PER_SECTION * sizeof(struct page)) + if (end - start < PAGES_PER_SECTION * sizeof(struct page)) err = vmemmap_populate_basepages(start, end, node, NULL); else if (boot_cpu_has(X86_FEATURE_PSE)) err = vmemmap_populate_hugepages(start, end, node, altmap); @@ -1639,8 +1637,6 @@ void register_page_bootmem_memmap(unsigned long section_nr, pmd_t *pmd; unsigned int nr_pmd_pages; struct page *page; - bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || - is_hugetlb_free_vmemmap_enabled(); for (; addr < end; addr = next) { pte_t *pte = NULL; @@ -1666,7 +1662,7 @@ void register_page_bootmem_memmap(unsigned long section_nr, } get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); - if (base_mapping) { + if (!boot_cpu_has(X86_FEATURE_PSE)) { next = (addr + PAGE_SIZE) & PAGE_MASK; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index cfde3bec2261..f11ba701e199 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -895,20 +895,6 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, } #endif -#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP -extern bool hugetlb_free_vmemmap_enabled; - -static inline bool is_hugetlb_free_vmemmap_enabled(void) -{ - return hugetlb_free_vmemmap_enabled; -} -#else -static inline bool is_hugetlb_free_vmemmap_enabled(void) -{ - return false; -} -#endif - #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; @@ -1063,13 +1049,14 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr pte_t *ptep, pte_t pte, unsigned long sz) { } - -static inline bool is_hugetlb_free_vmemmap_enabled(void) -{ - return false; -} #endif /* CONFIG_HUGETLB_PAGE */ +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +extern bool hugetlb_free_vmemmap_enabled; +#else +#define hugetlb_free_vmemmap_enabled false +#endif + static inline spinlock_t *huge_pte_lock(struct hstate *h, struct mm_struct *mm, pte_t *pte) { diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 29d1d742b565..492560b61999 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1056,7 +1056,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size) * populate a single PMD. */ return memmap_on_memory && - !is_hugetlb_free_vmemmap_enabled() && + !hugetlb_free_vmemmap_enabled && IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && size == memory_block_size_bytes() && IS_ALIGNED(vmemmap_size, PMD_SIZE) && -- cgit v1.2.3 From 6acfb5ba150cf75005ce85e0e25d79ef2fec287c Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Wed, 30 Jun 2021 18:51:29 -0700 Subject: mm: migrate: fix missing update page_private to hugetlb_page_subpool Since commit d6995da31122 ("hugetlb: use page.private for hugetlb specific page flags") converts page.private for hugetlb specific page flags. We should use hugetlb_page_subpool() to get the subpool pointer instead of page_private(). This 'could' prevent the migration of hugetlb pages. page_private(hpage) is now used for hugetlb page specific flags. At migration time, the only flag which could be set is HPageVmemmapOptimized. This flag will only be set if the new vmemmap reduction feature is enabled. In addition, !page_mapping() implies an anonymous mapping. So, this will prevent migration of hugetb pages in anonymous mappings if the vmemmap reduction feature is enabled. In addition, that if statement checked for the rare race condition of a page being migrated while in the process of being freed. Since that check is now wrong, we could leak hugetlb subpool usage counts. The commit forgot to update it in the page migration routine. So fix it. [songmuchun@bytedance.com: fix compiler error when !CONFIG_HUGETLB_PAGE reported by Randy] Link: https://lkml.kernel.org/r/20210521022747.35736-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210520025949.1866-1-songmuchun@bytedance.com Fixes: d6995da31122 ("hugetlb: use page.private for hugetlb specific page flags") Signed-off-by: Muchun Song Reported-by: Anshuman Khandual Reviewed-by: Mike Kravetz Acked-by: Michal Hocko Tested-by: Anshuman Khandual [arm64] Cc: Oscar Salvador Cc: David Hildenbrand Cc: Matthew Wilcox Cc: Xiongchun Duan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 5 +++++ mm/migrate.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index f11ba701e199..a58e11f2db15 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -898,6 +898,11 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; +static inline struct hugepage_subpool *hugetlb_page_subpool(struct page *hpage) +{ + return NULL; +} + static inline int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list) { diff --git a/mm/migrate.c b/mm/migrate.c index 8fc766e52e52..9bd6bc12aa72 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1293,7 +1293,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, * page_mapping() set, hugetlbfs specific move page routine will not * be called and we could leak usage counts for subpools. */ - if (page_private(hpage) && !page_mapping(hpage)) { + if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) { rc = -EBUSY; goto out_unlock; } -- cgit v1.2.3