[PATCHv1, RFC 13/33] filemap: allocate huge page in page_cache_read(), if allowed
From: Kirill A. Shutemov <hidden>
Date: 2016-07-26 00:35:15
Also in:
linux-ext4, linux-fsdevel, linux-mm, lkml
Subsystem:
filesystems (vfs and infrastructure), memory management, page cache, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Matthew Wilcox, Linus Torvalds
This patch adds basic functionality to put huge page into page cache. At the moment we only put huge pages into radix-tree if the range covered by the huge page is empty. Handling of shadow entires will be added later. Signed-off-by: Kirill A. Shutemov <redacted> --- include/linux/fs.h | 5 +++ include/linux/pagemap.h | 21 +++++++-- mm/filemap.c | 113 ++++++++++++++++++++++++++++++++++++++++++------ 3 files changed, 122 insertions(+), 17 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b7c9198d3f54..0208b41d8de2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -1861,6 +1861,11 @@ struct super_operations { #else #define S_DAX 0 /* Make all the DAX code disappear */ #endif +#define S_HUGE_MODE 0xc000 +#define S_HUGE_NEVER 0x0000 +#define S_HUGE_ALWAYS 0x4000 +#define S_HUGE_WITHIN_SIZE 0x8000 +#define S_HUGE_ADVISE 0xc000 /* * Note that nosuid etc flags are inode-specific: setting some file-system
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 81363b834900..d9cf4e0f35dc 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h@@ -191,14 +191,20 @@ static inline int page_cache_add_speculative(struct page *page, int count) } #ifdef CONFIG_NUMA -extern struct page *__page_cache_alloc(gfp_t gfp); +extern struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order); #else -static inline struct page *__page_cache_alloc(gfp_t gfp) +static inline struct page *__page_cache_alloc_order(gfp_t gfp, + unsigned int order) { - return alloc_pages(gfp, 0); + return alloc_pages(gfp, order); } #endif +static inline struct page *__page_cache_alloc(gfp_t gfp) +{ + return __page_cache_alloc_order(gfp, 0); +} + static inline struct page *page_cache_alloc(struct address_space *x) { return __page_cache_alloc(mapping_gfp_mask(x));
@@ -215,6 +221,15 @@ static inline gfp_t readahead_gfp_mask(struct address_space *x) __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN; } +extern bool __page_cache_allow_huge(struct address_space *x, pgoff_t offset); +static inline bool page_cache_allow_huge(struct address_space *x, + pgoff_t offset) +{ + if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) + return false; + return __page_cache_allow_huge(x, offset); +} + typedef int filler_t(void *, struct page *); pgoff_t page_cache_next_hole(struct address_space *mapping,
diff --git a/mm/filemap.c b/mm/filemap.c
index 7daedd910cf4..a3183e688718 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -636,14 +636,14 @@ static int __add_to_page_cache_locked(struct page *page, pgoff_t offset, gfp_t gfp_mask, void **shadowp) { - int huge = PageHuge(page); + int hugetlb = PageHuge(page); struct mem_cgroup *memcg; int error; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageSwapBacked(page), page); - if (!huge) { + if (!hugetlb) { error = mem_cgroup_try_charge(page, current->mm, gfp_mask, &memcg, false); if (error)
@@ -652,7 +652,7 @@ static int __add_to_page_cache_locked(struct page *page, error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM); if (error) { - if (!huge) + if (!hugetlb) mem_cgroup_cancel_charge(page, memcg, false); return error; }
@@ -662,16 +662,30 @@ static int __add_to_page_cache_locked(struct page *page, page->index = offset; spin_lock_irq(&mapping->tree_lock); - error = page_cache_tree_insert(mapping, page, shadowp); + if (PageTransHuge(page)) { + /* TODO: shadow handling */ + error = __radix_tree_insert(&mapping->page_tree, offset, + compound_order(page), page); + + if (!error) { + count_vm_event(THP_FILE_ALLOC); + mapping->nrpages += HPAGE_PMD_NR; + *shadowp = NULL; + __inc_node_page_state(page, NR_FILE_THPS); + } + } else { + error = page_cache_tree_insert(mapping, page, shadowp); + } radix_tree_preload_end(); if (unlikely(error)) goto err_insert; /* hugetlb pages do not participate in page cache accounting. */ - if (!huge) - __inc_node_page_state(page, NR_FILE_PAGES); + if (!hugetlb) + __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, + hpage_nr_pages(page)); spin_unlock_irq(&mapping->tree_lock); - if (!huge) + if (!hugetlb) mem_cgroup_commit_charge(page, memcg, false, false); trace_mm_filemap_add_to_page_cache(page); return 0;
@@ -679,7 +693,7 @@ err_insert: page->mapping = NULL; /* Leave page->index set: truncation relies upon it */ spin_unlock_irq(&mapping->tree_lock); - if (!huge) + if (!hugetlb) mem_cgroup_cancel_charge(page, memcg, false); put_page(page); return error;
@@ -736,7 +750,7 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping, EXPORT_SYMBOL_GPL(add_to_page_cache_lru); #ifdef CONFIG_NUMA -struct page *__page_cache_alloc(gfp_t gfp) +struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order) { int n; struct page *page;
@@ -746,14 +760,14 @@ struct page *__page_cache_alloc(gfp_t gfp) do { cpuset_mems_cookie = read_mems_allowed_begin(); n = cpuset_mem_spread_node(); - page = __alloc_pages_node(n, gfp, 0); + page = __alloc_pages_node(n, gfp, order); } while (!page && read_mems_allowed_retry(cpuset_mems_cookie)); return page; } - return alloc_pages(gfp, 0); + return alloc_pages(gfp, order); } -EXPORT_SYMBOL(__page_cache_alloc); +EXPORT_SYMBOL(__page_cache_alloc_order); #endif /*
@@ -1148,6 +1162,59 @@ repeat: } EXPORT_SYMBOL(find_lock_entry); +bool __page_cache_allow_huge(struct address_space *mapping, pgoff_t offset) +{ + struct inode *inode = mapping->host; + void __rcu **results; + unsigned long idx; + + offset = round_down(offset, HPAGE_PMD_NR); + + switch (inode->i_flags & S_HUGE_MODE) { + case S_HUGE_NEVER: + return false; + case S_HUGE_ALWAYS: + break; + case S_HUGE_WITHIN_SIZE: + if (DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) < + offset + HPAGE_PMD_NR) + return false; + break; + case S_HUGE_ADVISE: + /* TODO */ + return false; + default: + WARN_ON_ONCE(1); + return false; + } + + rcu_read_lock(); + if (radix_tree_gang_lookup_slot(&mapping->page_tree, &results, &idx, + offset, 1) && idx < offset + HPAGE_PMD_NR) { + rcu_read_unlock(); + return false; + } + rcu_read_unlock(); + + return true; + +} + +static struct page *page_cache_alloc_huge(struct address_space *mapping, + pgoff_t offset, gfp_t gfp_mask) +{ + struct page *page; + + if (!page_cache_allow_huge(mapping, offset)) + return NULL; + + gfp_mask |= __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN; + page = __page_cache_alloc_order(gfp_mask, HPAGE_PMD_ORDER); + if (page) + prep_transhuge_page(page); + return page; +} + /** * pagecache_get_page - find and get a page reference * @mapping: the address_space to search
@@ -2016,19 +2083,37 @@ static int page_cache_read(struct file *file, pgoff_t offset, gfp_t gfp_mask) { struct address_space *mapping = file->f_mapping; struct page *page; + pgoff_t hoffset; int ret; do { - page = __page_cache_alloc(gfp_mask|__GFP_COLD); + page = page_cache_alloc_huge(mapping, offset, gfp_mask); +no_huge: + if (!page) + page = __page_cache_alloc(gfp_mask|__GFP_COLD); if (!page) return -ENOMEM; - ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask & GFP_KERNEL); + if (PageTransHuge(page)) + hoffset = round_down(offset, HPAGE_PMD_NR); + else + hoffset = offset; + + ret = add_to_page_cache_lru(page, mapping, hoffset, + gfp_mask & GFP_KERNEL); if (ret == 0) ret = mapping->a_ops->readpage(file, page); else if (ret == -EEXIST) ret = 0; /* losing race to add is OK */ + if (ret && PageTransHuge(page)) { + delete_from_page_cache(page); + unlock_page(page); + put_page(page); + page = NULL; + goto no_huge; + } + put_page(page); } while (ret == AOP_TRUNCATED_PAGE);
--
2.8.1