[PATCH 8/9] mm: add API for setting a grace period cookie on compound pages
From: Michel Lespinasse <hidden>
Date: 2011-08-19 07:49:39
Also in:
lkml
Subsystem:
memory management, memory management - core, memory management - page allocator, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Linus Torvalds
This commit adds the page_get_gp_cookie() / page_gp_cookie_elapsed() API to be used on compound pages. page_get_gp_cookie() sets a cookie on a page and page_gp_cookie_elapsed() returns true if an rcu grace period has elapsed since the cookie was set. page_clear_gp_cookie() is called before freeing compound pages so that their state is always returned to a given standard (as enforced by free_pages_check() in mm/page_alloc.c) Signed-off-by: Michel Lespinasse <redacted> --- include/linux/mm.h | 22 ++++++++++++++++++++++ include/linux/mm_types.h | 6 +++++- mm/page_alloc.c | 1 + 3 files changed, 28 insertions(+), 1 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9ff5f2d..2649b59 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -494,6 +494,28 @@ static inline void set_compound_order(struct page *page, unsigned long order) page[1].lru.prev = (void *)order; } +static inline void page_get_gp_cookie(struct page *page) +{ + VM_BUG_ON(!PageHead(page)); + rcu_get_gp_cookie(&page[1].thp_create_timestamp); +} + +static inline bool page_gp_cookie_elapsed(struct page *page) +{ + VM_BUG_ON(!PageHead(page)); + return rcu_gp_cookie_elapsed(&page[1].thp_create_timestamp); +} + +static inline void page_clear_gp_cookie(struct page *page) +{ + VM_BUG_ON(!PageHead(page)); + VM_BUG_ON(offsetof(struct page, thp_create_timestamp) != + offsetof(struct page, mapping)); + VM_BUG_ON(sizeof(page->thp_create_timestamp) != + sizeof(page->mapping)); + page[1].mapping = 0; +} + #ifdef CONFIG_MMU /* * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 027935c..a6f99aa 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h@@ -12,6 +12,7 @@ #include <linux/completion.h> #include <linux/cpumask.h> #include <linux/page-debug-flags.h> +#include <linux/rcupdate.h> #include <asm/page.h> #include <asm/mmu.h>
@@ -66,7 +67,10 @@ struct page { spinlock_t ptl; #endif struct kmem_cache *slab; /* SLUB: Pointer to slab */ - struct page *first_page; /* Compound tail pages */ + struct { /* Compound tail pages */ + struct page *first_page; + struct rcu_cookie thp_create_timestamp; + }; }; union { pgoff_t index; /* Our offset within mapping. */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4e8985a..dc42355 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c@@ -342,6 +342,7 @@ out: static void free_compound_page(struct page *page) { + page_clear_gp_cookie(page); __free_pages_ok(page, compound_order(page)); }
--
1.7.3.1
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