From 89e004ea55abe201b29e2d6e35124101f1288ef7 Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Sat, 18 Oct 2008 20:26:43 -0700 Subject: SHM_LOCKED pages are unevictable Shmem segments locked into memory via shmctl(SHM_LOCKED) should not be kept on the normal LRU, since scanning them is a waste of time and might throw off kswapd's balancing algorithms. Place them on the unevictable LRU list instead. Use the AS_UNEVICTABLE flag to mark address_space of SHM_LOCKed shared memory regions as unevictable. Then these pages will be culled off the normal LRU lists during vmscan. Add new wrapper function to clear the mapping's unevictable state when/if shared memory segment is munlocked. Add 'scan_mapping_unevictable_page()' to mm/vmscan.c to scan all pages in the shmem segment's mapping [struct address_space] for evictability now that they're no longer locked. If so, move them to the appropriate zone lru list. Changes depend on [CONFIG_]UNEVICTABLE_LRU. [kosaki.motohiro@jp.fujitsu.com: revert shm change] Signed-off-by: Lee Schermerhorn Signed-off-by: Rik van Riel Signed-off-by: Kosaki Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/shm.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index e77ec698cf40..0add3fa5f547 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -737,6 +737,10 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf) case SHM_LOCK: case SHM_UNLOCK: { + struct file *uninitialized_var(shm_file); + + lru_add_drain_all(); /* drain pagevecs to lru lists */ + shp = shm_lock_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); -- cgit v1.2.3