diff options
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/transhuge.txt | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/Documentation/vm/transhuge.txt b/Documentation/vm/transhuge.txt index d9cb65cf5cfd..fb0e1f2a19cc 100644 --- a/Documentation/vm/transhuge.txt +++ b/Documentation/vm/transhuge.txt @@ -394,9 +394,9 @@ hugepage natively. Once finished you can drop the page table lock. Refcounting on THP is mostly consistent with refcounting on other compound pages: - - get_page()/put_page() and GUP operate in head page's ->_count. + - get_page()/put_page() and GUP operate in head page's ->_refcount. - - ->_count in tail pages is always zero: get_page_unless_zero() never + - ->_refcount in tail pages is always zero: get_page_unless_zero() never succeed on tail pages. - map/unmap of the pages with PTE entry increment/decrement ->_mapcount @@ -426,15 +426,15 @@ requests to split pinned huge page: it expects page count to be equal to sum of mapcount of all sub-pages plus one (split_huge_page caller must have reference for head page). -split_huge_page uses migration entries to stabilize page->_count and +split_huge_page uses migration entries to stabilize page->_refcount and page->_mapcount. We safe against physical memory scanners too: the only legitimate way scanner can get reference to a page is get_page_unless_zero(). -All tail pages has zero ->_count until atomic_add(). It prevent scanner +All tail pages has zero ->_refcount until atomic_add(). It prevent scanner from geting reference to tail page up to the point. After the atomic_add() -we don't care about ->_count value. We already known how many references +we don't care about ->_refcount value. We already known how many references with should uncharge from head page. For head page get_page_unless_zero() will succeed and we don't mind. It's |