memcg: fold mem_cgroup_stolen
It is only used in __mem_cgroup_begin_update_page_stat(), the name is confusing and 2 routines for one thing also confuse people, so fold this function seems more clear. [akpm@linux-foundation.org: fix typo, per Michal] Signed-off-by: Qiang Huang <h.huangqiang@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -1594,23 +1594,12 @@ static void mem_cgroup_end_move(struct mem_cgroup *memcg)
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}
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}
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/*
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/*
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* 2 routines for checking "mem" is under move_account() or not.
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* A routine for checking "mem" is under move_account() or not.
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*
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*
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* mem_cgroup_stolen() - checking whether a cgroup is mc.from or not. This
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* Checking a cgroup is mc.from or mc.to or under hierarchy of
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* is used for avoiding races in accounting. If true,
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* moving cgroups. This is for waiting at high-memory pressure
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* pc->mem_cgroup may be overwritten.
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* caused by "move".
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*
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* mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
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* under hierarchy of moving cgroups. This is for
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* waiting at hith-memory prressure caused by "move".
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*/
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*/
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static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
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{
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VM_BUG_ON(!rcu_read_lock_held());
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return atomic_read(&memcg->moving_account) > 0;
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}
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static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
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static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
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{
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{
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struct mem_cgroup *from;
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struct mem_cgroup *from;
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@ -1653,7 +1642,6 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
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* Take this lock when
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* Take this lock when
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* - a code tries to modify page's memcg while it's USED.
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* - a code tries to modify page's memcg while it's USED.
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* - a code tries to modify page state accounting in a memcg.
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* - a code tries to modify page state accounting in a memcg.
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* see mem_cgroup_stolen(), too.
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*/
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*/
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static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
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static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
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unsigned long *flags)
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unsigned long *flags)
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@ -2326,9 +2314,10 @@ again:
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* If this memory cgroup is not under account moving, we don't
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* If this memory cgroup is not under account moving, we don't
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* need to take move_lock_mem_cgroup(). Because we already hold
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* need to take move_lock_mem_cgroup(). Because we already hold
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* rcu_read_lock(), any calls to move_account will be delayed until
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* rcu_read_lock(), any calls to move_account will be delayed until
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* rcu_read_unlock() if mem_cgroup_stolen() == true.
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* rcu_read_unlock().
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*/
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*/
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if (!mem_cgroup_stolen(memcg))
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VM_BUG_ON(!rcu_read_lock_held());
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if (atomic_read(&memcg->moving_account) <= 0)
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return;
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return;
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move_lock_mem_cgroup(memcg, flags);
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move_lock_mem_cgroup(memcg, flags);
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