rmap_walk_locked() is the same as rmap_walk(), but caller takes care about relevant rmap lock.
It's preparation to switch THP splitting from custom rmap walk in freeze_page()/unfreeze_page() to generic one. Signed-off-by: Kirill A. Shutemov <[email protected]> --- include/linux/rmap.h | 1 + mm/rmap.c | 41 ++++++++++++++++++++++++++++++++--------- 2 files changed, 33 insertions(+), 9 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index a07f42bedda3..a5875e9b4a27 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -266,6 +266,7 @@ struct rmap_walk_control { }; int rmap_walk(struct page *page, struct rmap_walk_control *rwc); +int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); #else /* !CONFIG_MMU */ diff --git a/mm/rmap.c b/mm/rmap.c index 02f0bfc3c80a..30b739ce0ffa 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1715,14 +1715,21 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page, * vm_flags for that VMA. That should be OK, because that vma shouldn't be * LOCKED. */ -static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) +static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc, + bool locked) { struct anon_vma *anon_vma; pgoff_t pgoff; struct anon_vma_chain *avc; int ret = SWAP_AGAIN; - anon_vma = rmap_walk_anon_lock(page, rwc); + if (locked) { + anon_vma = page_anon_vma(page); + /* anon_vma disappear under us? */ + VM_BUG_ON_PAGE(!anon_vma, page); + } else { + anon_vma = rmap_walk_anon_lock(page, rwc); + } if (!anon_vma) return ret; @@ -1742,7 +1749,9 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) if (rwc->done && rwc->done(page)) break; } - anon_vma_unlock_read(anon_vma); + + if (!locked) + anon_vma_unlock_read(anon_vma); return ret; } @@ -1759,9 +1768,10 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) * vm_flags for that VMA. That should be OK, because that vma shouldn't be * LOCKED. */ -static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) +static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, + bool locked) { - struct address_space *mapping = page->mapping; + struct address_space *mapping = page_mapping(page); pgoff_t pgoff; struct vm_area_struct *vma; int ret = SWAP_AGAIN; @@ -1778,7 +1788,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) return ret; pgoff = page_to_pgoff(page); - i_mmap_lock_read(mapping); + if (!locked) + i_mmap_lock_read(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { unsigned long address = vma_address(page, vma); @@ -1795,7 +1806,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) } done: - i_mmap_unlock_read(mapping); + if (!locked) + i_mmap_unlock_read(mapping); return ret; } @@ -1804,9 +1816,20 @@ int rmap_walk(struct page *page, struct rmap_walk_control *rwc) if (unlikely(PageKsm(page))) return rmap_walk_ksm(page, rwc); else if (PageAnon(page)) - return rmap_walk_anon(page, rwc); + return rmap_walk_anon(page, rwc, false); + else + return rmap_walk_file(page, rwc, false); +} + +/* Like rmap_walk, but caller holds relevant rmap lock */ +int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) +{ + /* no ksm support for now */ + VM_BUG_ON_PAGE(PageKsm(page), page); + if (PageAnon(page)) + return rmap_walk_anon(page, rwc, true); else - return rmap_walk_file(page, rwc); + return rmap_walk_file(page, rwc, true); } #ifdef CONFIG_HUGETLB_PAGE -- 2.7.0
