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Howlett" , Usama Arif , Kiryl Shutsemau , Dave Chinner , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 5/7] mm: list_lru: introduce caller locking for additions and deletions Message-ID: References: <20260312205321.638053-1-hannes@cmpxchg.org> <20260312205321.638053-6-hannes@cmpxchg.org> <46d9173e-98cd-4f59-b0f3-e477afd5283b@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46d9173e-98cd-4f59-b0f3-e477afd5283b@kernel.org> On Tue, Mar 17, 2026 at 11:00:59AM +0100, David Hildenbrand (Arm) wrote: > On 3/12/26 21:51, Johannes Weiner wrote: > > -/* The caller must ensure the memcg lifetime. */ > > -bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, > > - struct mem_cgroup *memcg) > > +struct list_lru_one *list_lru_lock(struct list_lru *lru, int nid, > > + struct mem_cgroup *memcg) > > { > > - struct list_lru_node *nlru = &lru->node[nid]; > > - struct list_lru_one *l; > > + return lock_list_lru_of_memcg(lru, nid, memcg, false, NULL, false); > > The two "bool" parameters really are ugly. Fortunately this is only an > internal function. Yeah, I absolutely hate this too. I only didn't look further because it's internal, but... > The callers are still a bit hard to read; we could add /*skip=empty=*/true). > > like > > return lock_list_lru_of_memcg(lru, nid, memcg, /* irq= */false, NULL, > /* skip_empty= */false); > > Like we do in other code. But I guess we should do it consistently then > (or better add some proper flags). > > Anyhow, something that could be cleaned up later. This is a great idea. I have to send a v3 for the fix in __folio_freeze_and_split_unmapped() and the lockdep key, so I'll make this change along with it. > > +void list_lru_unlock(struct list_lru_one *l) > > +{ > > + unlock_list_lru(l, false, NULL); > > +} > > + > > +struct list_lru_one *list_lru_lock_irqsave(struct list_lru *lru, int nid, > > + struct mem_cgroup *memcg, > > + unsigned long *flags) > > +{ > > + return lock_list_lru_of_memcg(lru, nid, memcg, true, flags, false); > > And here it gets really confusing. true false false ... am I reading > binary code? > > I guess the second "false" should actually be "NULL" :) Good catch, I'll fix that. > > +/* The caller must ensure the memcg lifetime. */ > > +bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, > > + struct mem_cgroup *memcg) > > +{ > > + struct list_lru_one *l; > > + bool ret; > > + > > + l = list_lru_lock(lru, nid, memcg); > > + ret = __list_lru_add(lru, l, item, nid, memcg); > > + list_lru_unlock(l); > > + return ret; > > +} > > Nice. > > Reviewed-by: David Hildenbrand (Arm) Thanks for your review!