rmap_walk_locked() is the same as rmap_walk(), but caller takes care about relevant rmap lock. It only supports anonymous pages for now.
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 | 25 +++++++++++++++++++++---- 2 files changed, 22 insertions(+), 4 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index bdf597c4f0be..23a03fbeef61 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -280,6 +280,7 @@ 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 79f3bf047f38..a9cffb784502 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1719,14 +1719,21 @@ 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; @@ -1746,7 +1753,9 @@ 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; } @@ -1808,11 +1817,19 @@ 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); } +/* Like rmap_walk, but caller holds relevant rmap lock */ +int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) +{ + /* only for anon pages for now */ + VM_BUG_ON_PAGE(!PageAnon(page) || PageKsm(page), page); + return rmap_walk_anon(page, rwc, true); +} + #ifdef CONFIG_HUGETLB_PAGE /* * The following three functions are for anonymous (private mapped) hugepages. -- 2.7.0
