Hello Roman Gushchin,
Commit e548ad4a7cbf ("mm: memcg: move charge migration code to
memcontrol-v1.c") from Jun 24, 2024 (linux-next), leads to the
following Smatch static checker warning:
mm/memcontrol-v1.c:609 mem_cgroup_move_charge_write()
warn: was expecting a 64 bit value instead of '~(1 | 2)'
mm/memcontrol-v1.c
599 #ifdef CONFIG_MMU
600 static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
601 struct cftype *cft, u64 val)
602 {
603 struct mem_cgroup *memcg = mem_cgroup_from_css(css);
604
605 pr_warn_once("Cgroup memory moving (move_charge_at_immigrate) is deprecated. "
606 "Please report your usecase to linux-mm@xxxxxxxxx if you "
607 "depend on this functionality.\n");
608
--> 609 if (val & ~MOVE_MASK)
val is a u64 and MOVE_MASK is a u32. This only checks if something in the low
32 bits is set and it ignores the high 32 bits.
610 return -EINVAL;
611
612 /*
613 * No kind of locking is needed in here, because ->can_attach() will
614 * check this value once in the beginning of the process, and then carry
615 * on with stale data. This means that changes to this value will only
616 * affect task migrations starting after the change.
617 */
618 memcg->move_charge_at_immigrate = val;
619 return 0;
620 }
regards,
dan carpenter
