From 769848c03895b63e5662eb7e4ec8c4866f7d0183 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 17 Jul 2007 04:03:05 -0700 Subject: Add __GFP_MOVABLE for callers to flag allocations from high memory that may be migrated It is often known at allocation time whether a page may be migrated or not. This patch adds a flag called __GFP_MOVABLE and a new mask called GFP_HIGH_MOVABLE. Allocations using the __GFP_MOVABLE can be either migrated using the page migration mechanism or reclaimed by syncing with backing storage and discarding. An API function very similar to alloc_zeroed_user_highpage() is added for __GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable(). The flags used by alloc_zeroed_user_highpage() are not changed because it would change the semantics of an existing API. After this patch is applied there are no in-kernel users of alloc_zeroed_user_highpage() so it probably should be marked deprecated if this patch is merged. Note that this patch includes a minor cleanup to the use of __GFP_ZERO in shmem.c to keep all flag modifications to inode->mapping in the shmem_dir_alloc() helper function. This clean-up suggestion is courtesy of Hugh Dickens. Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the concept. Credit to Hugh Dickens for catching issues with shmem swap vector and ramfs allocations. [akpm@linux-foundation.org: build fix] [hugh@veritas.com: __GFP_ZERO cleanup] Signed-off-by: Mel Gorman Cc: Andy Whitcroft Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'mm/shmem.c') diff --git a/mm/shmem.c b/mm/shmem.c index 0493e4d0bca..e49181d9d89 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -93,8 +93,11 @@ static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) * The above definition of ENTRIES_PER_PAGE, and the use of * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: * might be reconsidered if it ever diverges from PAGE_SIZE. + * + * __GFP_MOVABLE is masked out as swap vectors cannot move */ - return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); + return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __GFP_ZERO, + PAGE_CACHE_SHIFT-PAGE_SHIFT); } static inline void shmem_dir_free(struct page *page) @@ -372,7 +375,7 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long } spin_unlock(&info->lock); - page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); + page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); if (page) set_page_private(page, 0); spin_lock(&info->lock); -- cgit v1.2.3-70-g09d2