return;
pc = lookup_page_cgroup(page);
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
smp_rmb();
/* unused page is not rotated. */
if (!PageCgroupUsed(pc))
if (mem_cgroup_disabled())
return;
pc = lookup_page_cgroup(page);
- /* barrier to sync with "charge" */
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
smp_rmb();
if (!PageCgroupUsed(pc))
return;
return NULL;
pc = lookup_page_cgroup(page);
+ /*
+ * Used bit is set without atomic ops but after smp_wmb().
+ * For making pc->mem_cgroup visible, insert smp_rmb() here.
+ */
+ smp_rmb();
+ if (!PageCgroupUsed(pc))
+ return NULL;
+
mz = page_cgroup_zoneinfo(pc);
if (!mz)
return NULL;
if (pc->mem_cgroup != from)
goto out;
- css_put(&from->css);
res_counter_uncharge(&from->res, PAGE_SIZE);
mem_cgroup_charge_statistics(from, pc, false);
if (do_swap_account)
res_counter_uncharge(&from->memsw, PAGE_SIZE);
+ css_put(&from->css);
+
+ css_get(&to->css);
pc->mem_cgroup = to;
mem_cgroup_charge_statistics(to, pc, true);
- css_get(&to->css);
ret = 0;
out:
unlock_page_cgroup(pc);
if (ret || !parent)
return ret;
- if (!get_page_unless_zero(page))
- return -EBUSY;
+ if (!get_page_unless_zero(page)) {
+ ret = -EBUSY;
+ goto uncharge;
+ }
ret = isolate_lru_page(page);
ret = mem_cgroup_move_account(pc, child, parent);
- /* drop extra refcnt by try_charge() (move_account increment one) */
- css_put(&parent->css);
putback_lru_page(page);
if (!ret) {
put_page(page);
+ /* drop extra refcnt by try_charge() */
+ css_put(&parent->css);
return 0;
}
- /* uncharge if move fails */
+
cancel:
+ put_page(page);
+uncharge:
+ /* drop extra refcnt by try_charge() */
+ css_put(&parent->css);
+ /* uncharge if move fails */
res_counter_uncharge(&parent->res, PAGE_SIZE);
if (do_swap_account)
res_counter_uncharge(&parent->memsw, PAGE_SIZE);
- put_page(page);
return ret;
}