From faecd8dd852d4e4a63a1b8ad43e5df8e41ee0336 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Tue, 21 Jan 2014 15:49:46 -0800 Subject: mm/rmap: factor lock function out of rmap_walk_anon() When we traverse anon_vma, we need to take a read-side anon_lock. But there is subtle difference in the situation so that we can't use same method to take a lock in each cases. Therefore, we need to make rmap_walk_anon() taking difference lock function. This patch is the first step, factoring lock function for anon_lock out of rmap_walk_anon(). It will be used in case of removing migration entry and in default of rmap_walk_anon(). Signed-off-by: Joonsoo Kim Reviewed-by: Naoya Horiguchi Cc: Mel Gorman Cc: Hugh Dickins Cc: Rik van Riel Cc: Ingo Molnar Cc: Hillf Danton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 7eab4ed..5a79bf5 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1684,6 +1684,24 @@ void __put_anon_vma(struct anon_vma *anon_vma) } #ifdef CONFIG_MIGRATION +static struct anon_vma *rmap_walk_anon_lock(struct page *page) +{ + struct anon_vma *anon_vma; + + /* + * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() + * because that depends on page_mapped(); but not all its usages + * are holding mmap_sem. Users without mmap_sem are required to + * take a reference count to prevent the anon_vma disappearing + */ + anon_vma = page_anon_vma(page); + if (!anon_vma) + return NULL; + + anon_vma_lock_read(anon_vma); + return anon_vma; +} + /* * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): * Called by migrate.c to remove migration ptes, but might be used more later. @@ -1696,16 +1714,10 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, struct anon_vma_chain *avc; int ret = SWAP_AGAIN; - /* - * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() - * because that depends on page_mapped(); but not all its usages - * are holding mmap_sem. Users without mmap_sem are required to - * take a reference count to prevent the anon_vma disappearing - */ - anon_vma = page_anon_vma(page); + anon_vma = rmap_walk_anon_lock(page); if (!anon_vma) return ret; - anon_vma_lock_read(anon_vma); + anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { struct vm_area_struct *vma = avc->vma; unsigned long address = vma_address(page, vma); -- cgit v1.1