diff options
Diffstat (limited to 'mm/page_cgroup.c')
| -rw-r--r-- | mm/page_cgroup.c | 34 |
1 files changed, 32 insertions, 2 deletions
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index 3d535d59482..3dd88539a0e 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -335,6 +335,37 @@ not_enough_page: } /** + * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry. + * @end: swap entry to be cmpxchged + * @old: old id + * @new: new id + * + * Returns old id at success, 0 at failure. + * (There is no mem_cgroup useing 0 as its id) + */ +unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, + unsigned short old, unsigned short new) +{ + int type = swp_type(ent); + unsigned long offset = swp_offset(ent); + unsigned long idx = offset / SC_PER_PAGE; + unsigned long pos = offset & SC_POS_MASK; + struct swap_cgroup_ctrl *ctrl; + struct page *mappage; + struct swap_cgroup *sc; + + ctrl = &swap_cgroup_ctrl[type]; + + mappage = ctrl->map[idx]; + sc = page_address(mappage); + sc += pos; + if (cmpxchg(&sc->id, old, new) == old) + return old; + else + return 0; +} + +/** * swap_cgroup_record - record mem_cgroup for this swp_entry. * @ent: swap entry to be recorded into * @mem: mem_cgroup to be recorded @@ -358,8 +389,7 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - old = sc->id; - sc->id = id; + old = xchg(&sc->id, id); return old; } |