From 83cde9e8ba95d180eaefefe834958fbf7008cf39 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:54:21 -0800 Subject: mm: use new helper functions around the i_mmap_mutex Convert all open coded mutex_lock/unlock calls to the i_mmap_[lock/unlock]_write() helpers. Signed-off-by: Davidlohr Bueso Acked-by: Rik van Riel Acked-by: "Kirill A. Shutemov" Acked-by: Hugh Dickins Cc: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Srikar Dronamraju Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index 45eba36fd673..bea03f6bec61 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1690,7 +1690,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) if (!mapping) return ret; - mutex_lock(&mapping->i_mmap_mutex); + i_mmap_lock_write(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { unsigned long address = vma_address(page, vma); @@ -1713,7 +1713,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) ret = rwc->file_nonlinear(page, mapping, rwc->arg); done: - mutex_unlock(&mapping->i_mmap_mutex); + i_mmap_unlock_write(mapping); return ret; } -- cgit v1.2.2 From c8c06efa8b552608493b7066c234cfa82c47fcea Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:54:24 -0800 Subject: mm: convert i_mmap_mutex to rwsem The i_mmap_mutex is a close cousin of the anon vma lock, both protecting similar data, one for file backed pages and the other for anon memory. To this end, this lock can also be a rwsem. In addition, there are some important opportunities to share the lock when there are no tree modifications. This conversion is straightforward. For now, all users take the write lock. [sfr@canb.auug.org.au: update fremap.c] Signed-off-by: Davidlohr Bueso Reviewed-by: Rik van Riel Acked-by: "Kirill A. Shutemov" Acked-by: Hugh Dickins Cc: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Srikar Dronamraju Acked-by: Mel Gorman Signed-off-by: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index bea03f6bec61..18247f89f1a8 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -23,7 +23,7 @@ * inode->i_mutex (while writing or truncating, not reading or faulting) * mm->mmap_sem * page->flags PG_locked (lock_page) - * mapping->i_mmap_mutex + * mapping->i_mmap_rwsem * anon_vma->rwsem * mm->page_table_lock or pte_lock * zone->lru_lock (in mark_page_accessed, isolate_lru_page) @@ -1260,7 +1260,7 @@ out_mlock: /* * We need mmap_sem locking, Otherwise VM_LOCKED check makes * unstable result and race. Plus, We can't wait here because - * we now hold anon_vma->rwsem or mapping->i_mmap_mutex. + * we now hold anon_vma->rwsem or mapping->i_mmap_rwsem. * if trylock failed, the page remain in evictable lru and later * vmscan could retry to move the page to unevictable lru if the * page is actually mlocked. @@ -1684,7 +1684,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) * The page lock not only makes sure that page->mapping cannot * suddenly be NULLified by truncation, it makes sure that the * structure at mapping cannot be freed and reused yet, - * so we can safely take mapping->i_mmap_mutex. + * so we can safely take mapping->i_mmap_rwsem. */ VM_BUG_ON_PAGE(!PageLocked(page), page); -- cgit v1.2.2 From 3dec0ba0be6a532cac949e02b853021bf6d57dad Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:54:27 -0800 Subject: mm/rmap: share the i_mmap_rwsem Similarly to the anon memory counterpart, we can share the mapping's lock ownership as the interval tree is not modified when doing doing the walk, only the file page. Signed-off-by: Davidlohr Bueso Acked-by: Rik van Riel Acked-by: "Kirill A. Shutemov" Acked-by: Hugh Dickins Cc: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Srikar Dronamraju Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index 18247f89f1a8..14ad2b3b0f54 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1690,7 +1690,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) if (!mapping) return ret; - i_mmap_lock_write(mapping); + + i_mmap_lock_read(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { unsigned long address = vma_address(page, vma); @@ -1711,9 +1712,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) goto done; ret = rwc->file_nonlinear(page, mapping, rwc->arg); - done: - i_mmap_unlock_write(mapping); + i_mmap_unlock_read(mapping); return ret; } -- cgit v1.2.2 From b258d860652934b5e014408302335430b81bd7ce Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:55:04 -0800 Subject: mm/rmap: calculate page offset when needed Call page_to_pgoff() to get the page offset once we are sure we actually need it, and any very obvious initial function checks have passed. Trivial micro-optimization, and potentially save some cycles. Signed-off-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'mm/rmap.c') diff --git a/mm/rmap.c b/mm/rmap.c index 14ad2b3b0f54..c52f43a69eea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1635,7 +1635,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page, static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) { struct anon_vma *anon_vma; - pgoff_t pgoff = page_to_pgoff(page); + pgoff_t pgoff; struct anon_vma_chain *avc; int ret = SWAP_AGAIN; @@ -1643,6 +1643,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) if (!anon_vma) return ret; + pgoff = page_to_pgoff(page); 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); @@ -1676,7 +1677,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) { struct address_space *mapping = page->mapping; - pgoff_t pgoff = page_to_pgoff(page); + pgoff_t pgoff; struct vm_area_struct *vma; int ret = SWAP_AGAIN; @@ -1691,6 +1692,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) if (!mapping) return ret; + pgoff = page_to_pgoff(page); i_mmap_lock_read(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { unsigned long address = vma_address(page, vma); -- cgit v1.2.2