From: Johannes Weiner Date: Tue, 15 Mar 2016 21:57:25 +0000 (-0700) Subject: mm: remove unnecessary uses of lock_page_memcg() X-Git-Tag: v4.6-rc1~137^2~28 X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=fdf1cdb91b6ab7a8a91df68c384f36b8a0909cab;p=cascardo%2Flinux.git mm: remove unnecessary uses of lock_page_memcg() There are several users that nest lock_page_memcg() inside lock_page() to prevent page->mem_cgroup from changing. But the page lock prevents pages from moving between cgroups, so that is unnecessary overhead. Remove lock_page_memcg() in contexts with locked contexts and fix the debug code in the page stat functions to be okay with the page lock. Signed-off-by: Johannes Weiner Acked-by: Vladimir Davydov Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index d560c9a3cadf..f0c4bec6565b 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -28,6 +28,7 @@ #include #include #include +#include struct mem_cgroup; struct page; @@ -464,18 +465,19 @@ void unlock_page_memcg(struct page *page); * @idx: page state item to account * @val: number of pages (positive or negative) * - * Callers must use lock_page_memcg() to prevent double accounting - * when the page is concurrently being moved to another memcg: + * The @page must be locked or the caller must use lock_page_memcg() + * to prevent double accounting when the page is concurrently being + * moved to another memcg: * - * lock_page_memcg(page); + * lock_page(page) or lock_page_memcg(page) * if (TestClearPageState(page)) * mem_cgroup_update_page_stat(page, state, -1); - * unlock_page_memcg(page); + * unlock_page(page) or unlock_page_memcg(page) */ static inline void mem_cgroup_update_page_stat(struct page *page, enum mem_cgroup_stat_index idx, int val) { - VM_BUG_ON(!rcu_read_lock_held()); + VM_BUG_ON(!(rcu_read_lock_held() || PageLocked(page))); if (page->mem_cgroup) this_cpu_add(page->mem_cgroup->stat->count[idx], val); diff --git a/mm/filemap.c b/mm/filemap.c index 8e629c4ef0c8..61b441b191ad 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -176,8 +176,7 @@ static void page_cache_tree_delete(struct address_space *mapping, /* * Delete a page from the page cache and free it. Caller has to make * sure the page is locked and that nobody else uses it - or that usage - * is safe. The caller must hold the mapping's tree_lock and - * lock_page_memcg(). + * is safe. The caller must hold the mapping's tree_lock. */ void __delete_from_page_cache(struct page *page, void *shadow) { @@ -260,11 +259,9 @@ void delete_from_page_cache(struct page *page) freepage = mapping->a_ops->freepage; - lock_page_memcg(page); spin_lock_irqsave(&mapping->tree_lock, flags); __delete_from_page_cache(page, NULL); spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); if (freepage) freepage(page); @@ -557,7 +554,6 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) new->mapping = mapping; new->index = offset; - lock_page_memcg(old); spin_lock_irqsave(&mapping->tree_lock, flags); __delete_from_page_cache(old, NULL); error = radix_tree_insert(&mapping->page_tree, offset, new); @@ -572,7 +568,6 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) if (PageSwapBacked(new)) __inc_zone_page_state(new, NR_SHMEM); spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(old); mem_cgroup_migrate(old, new); radix_tree_preload_end(); if (freepage) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d7cf2c53d125..11ff8f758631 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2700,7 +2700,6 @@ int clear_page_dirty_for_io(struct page *page) * always locked coming in here, so we get the desired * exclusion. */ - lock_page_memcg(page); wb = unlocked_inode_to_wb_begin(inode, &locked); if (TestClearPageDirty(page)) { mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_DIRTY); @@ -2709,7 +2708,6 @@ int clear_page_dirty_for_io(struct page *page) ret = 1; } unlocked_inode_to_wb_end(inode, locked); - unlock_page_memcg(page); return ret; } return TestClearPageDirty(page); diff --git a/mm/truncate.c b/mm/truncate.c index 87311af936f2..7598b552ae03 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -527,7 +527,6 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) return 0; - lock_page_memcg(page); spin_lock_irqsave(&mapping->tree_lock, flags); if (PageDirty(page)) goto failed; @@ -535,7 +534,6 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) BUG_ON(page_has_private(page)); __delete_from_page_cache(page, NULL); spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); if (mapping->a_ops->freepage) mapping->a_ops->freepage(page); @@ -544,7 +542,6 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) return 1; failed: spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); return 0; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 34f7e2dae0a0..dd984470248f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -607,7 +607,6 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); - lock_page_memcg(page); spin_lock_irqsave(&mapping->tree_lock, flags); /* * The non racy check for a busy page. @@ -647,7 +646,6 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page); spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); swapcache_free(swap); } else { void (*freepage)(struct page *); @@ -675,7 +673,6 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, shadow = workingset_eviction(mapping, page); __delete_from_page_cache(page, shadow); spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); if (freepage != NULL) freepage(page); @@ -685,7 +682,6 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, cannot_free: spin_unlock_irqrestore(&mapping->tree_lock, flags); - unlock_page_memcg(page); return 0; }