From 0139aa7b7fa12ceef095d99dc36606a5b10ab83a Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 19 May 2016 17:10:49 -0700 Subject: mm: rename _count, field of the struct page, to _refcount Many developers already know that field for reference count of the struct page is _count and atomic type. They would try to handle it directly and this could break the purpose of page reference count tracepoint. To prevent direct _count modification, this patch rename it to _refcount and add warning message on the code. After that, developer who need to handle reference count will find that field should not be accessed directly. [akpm@linux-foundation.org: fix comments, per Vlastimil] [akpm@linux-foundation.org: Documentation/vm/transhuge.txt too] [sfr@canb.auug.org.au: sync ethernet driver changes] Signed-off-by: Joonsoo Kim Signed-off-by: Stephen Rothwell Cc: Vlastimil Babka Cc: Hugh Dickins Cc: Johannes Berg Cc: "David S. Miller" Cc: Sunil Goutham Cc: Chris Metcalf Cc: Manish Chopra Cc: Yuval Mintz Cc: Tariq Toukan Cc: Saeed Mahameed Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 4 ++-- mm/internal.h | 2 +- mm/page_alloc.c | 4 ++-- mm/slub.c | 4 ++-- mm/vmscan.c | 4 ++-- 5 files changed, 9 insertions(+), 9 deletions(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b49ee12..f8ac8f5 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3113,7 +3113,7 @@ static void __split_huge_page_tail(struct page *head, int tail, VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); /* - * tail_page->_count is zero and not changing from under us. But + * tail_page->_refcount is zero and not changing from under us. But * get_page_unless_zero() may be running from under us on the * tail_page. If we used atomic_set() below instead of atomic_inc(), we * would then run atomic_set() concurrently with @@ -3340,7 +3340,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) if (mlocked) lru_add_drain(); - /* Prevent deferred_split_scan() touching ->_count */ + /* Prevent deferred_split_scan() touching ->_refcount */ spin_lock_irqsave(&pgdata->split_queue_lock, flags); count = page_count(head); mapcount = total_mapcount(head); diff --git a/mm/internal.h b/mm/internal.h index b79abb6..098a89e 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -58,7 +58,7 @@ static inline unsigned long ra_submit(struct file_ra_state *ra, } /* - * Turn a non-refcounted page (->_count == 0) into refcounted with + * Turn a non-refcounted page (->_refcount == 0) into refcounted with * a count of one. */ static inline void set_page_refcounted(struct page *page) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index c1069ef..4ce57f9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -794,7 +794,7 @@ static inline int free_pages_check(struct page *page) if (unlikely(page->mapping != NULL)) bad_reason = "non-NULL mapping"; if (unlikely(page_ref_count(page) != 0)) - bad_reason = "nonzero _count"; + bad_reason = "nonzero _refcount"; if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) { bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set"; bad_flags = PAGE_FLAGS_CHECK_AT_FREE; @@ -6864,7 +6864,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, * We can't use page_count without pin a page * because another CPU can free compound page. * This check already skips compound tails of THP - * because their page->_count is zero at all time. + * because their page->_refcount is zero at all time. */ if (!page_ref_count(page)) { if (PageBuddy(page)) diff --git a/mm/slub.c b/mm/slub.c index 8671de2..cf1faa4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -329,8 +329,8 @@ static inline void set_page_slub_counters(struct page *page, unsigned long count tmp.counters = counters_new; /* * page->counters can cover frozen/inuse/objects as well - * as page->_count. If we assign to ->counters directly - * we run the risk of losing updates to page->_count, so + * as page->_refcount. If we assign to ->counters directly + * we run the risk of losing updates to page->_refcount, so * be careful and only assign to the fields we need. */ page->frozen = tmp.frozen; diff --git a/mm/vmscan.c b/mm/vmscan.c index 142cb61..d3a02ac 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -633,7 +633,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, * * Reversing the order of the tests ensures such a situation cannot * escape unnoticed. The smp_rmb is needed to ensure the page->flags - * load is not satisfied before that of page->_count. + * load is not satisfied before that of page->_refcount. * * Note that if SetPageDirty is always performed via set_page_dirty, * and thus under tree_lock, then this ordering is not required. @@ -1720,7 +1720,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, * It is safe to rely on PG_active against the non-LRU pages in here because * nobody will play with that bit on a non-LRU page. * - * The downside is that we have to touch page->_count against each page. + * The downside is that we have to touch page->_refcount against each page. * But we had to alter page->flags anyway. */ -- cgit v1.1