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Date: Thu, 28 Jan 2021 17:31:49 +0100 From: Uladzislau Rezki <urezki@...il.com> To: qiang.zhang@...driver.com Cc: urezki@...il.com, paulmck@...nel.org, joel@...lfernandes.org, rcu@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] kvfree_rcu: Release page cache under memory pressure Hello, Zqiang. See below some nits: > > Add free per-cpu existing krcp's page cache operation, when > the system is under memory pressure. > > Signed-off-by: Zqiang <qiang.zhang@...driver.com> > --- > kernel/rcu/tree.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index c1ae1e52f638..4e1c14b12bdd 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -3571,17 +3571,41 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > } > EXPORT_SYMBOL_GPL(kvfree_call_rcu); > > +static inline int free_krc_page_cache(struct kfree_rcu_cpu *krcp) Do we need it "inlined"? > +{ > + unsigned long flags; > + struct kvfree_rcu_bulk_data *bnode; > + int i, num = 0; > + > + for (i = 0; i < rcu_min_cached_objs; i++) { > + raw_spin_lock_irqsave(&krcp->lock, flags); > + bnode = get_cached_bnode(krcp); > + raw_spin_unlock_irqrestore(&krcp->lock, flags); > + if (!bnode) > + break; > + free_page((unsigned long)bnode); > + num++; > + } > + > + return num; Get rid of "num" and return i instead? > +} > + > static unsigned long > kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) > { > int cpu; > unsigned long count = 0; > + unsigned long flags; > > /* Snapshot count of all CPUs */ > for_each_possible_cpu(cpu) { > struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); > > count += READ_ONCE(krcp->count); > + > + raw_spin_lock_irqsave(&krcp->lock, flags); > + count += krcp->nr_bkv_objs; > + raw_spin_unlock_irqrestore(&krcp->lock, flags); > } > > return count; > @@ -3604,6 +3628,8 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) > else > raw_spin_unlock_irqrestore(&krcp->lock, flags); > > + count += free_krc_page_cache(krcp); Move it upper right after count = krcp->count;, so a "count" is set in one place what i more readable and clear? Thank you! -- Vlad Rezki
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