linux-kernel - Re: [PATCH 05/20] mm: zswap: clean up zswap_entry

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Message-ID: <Zbkrms4k100Hdu7Q@google.com>
Date: Tue, 30 Jan 2024 17:02:18 +0000
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Nhat Pham <nphamcs@...il.com>
Cc: Johannes Weiner <hannes@...xchg.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	Chengming Zhou <zhouchengming@...edance.com>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/20] mm: zswap: clean up zswap_entry_put()

On Tue, Jan 30, 2024 at 08:31:22AM -0800, Nhat Pham wrote:
> On Mon, Jan 29, 2024 at 11:51 PM Yosry Ahmed <yosryahmed@...gle.com> wrote:
> >
> > On Mon, Jan 29, 2024 at 08:36:41PM -0500, Johannes Weiner wrote:
> > > Remove stale comment and unnecessary local variable.
> > >
> > > Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> > > ---
> > >  mm/zswap.c | 10 +++-------
> > >  1 file changed, 3 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/mm/zswap.c b/mm/zswap.c
> > > index 0c6adaf2fdb6..7a7e8da2b4f8 100644
> > > --- a/mm/zswap.c
> > > +++ b/mm/zswap.c
> > > @@ -546,15 +546,11 @@ static void zswap_entry_get(struct zswap_entry *entry)
> > >       entry->refcount++;
> > >  }
> > >
> > > -/* caller must hold the tree lock
> > > -* remove from the tree and free it, if nobody reference the entry
> > > -*/
> > > +/* caller must hold the tree lock */
> >
> > We should replace all those "caller must hold the tree lock" comments
> > with lockdep_assert_held() or assert_spin_locked() or something.
> >
> > I can send follow up patches on top if you don't want to resend this
> > series.
> 
> Agree. There's also this:
> 
> /* should be called under RCU */
> #ifdef CONFIG_MEMCG
> static inline struct mem_cgroup *mem_cgroup_from_entry(struct
> zswap_entry *entry)
> {
> return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
> }
> 
> which you pointed out in the per-cgroup zswap LRU review :)

I will send out a patch this week or so.