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Tue, 30 Jan 2024 08:31:32 -0800 (PST) MIME-Version: 1.0 References: <20240130014208.565554-1-hannes@cmpxchg.org> <20240130014208.565554-6-hannes@cmpxchg.org> In-Reply-To: From: Nhat Pham Date: Tue, 30 Jan 2024 08:31:22 -0800 Message-ID: Subject: Re: [PATCH 05/20] mm: zswap: clean up zswap_entry_put() To: Yosry Ahmed Cc: Johannes Weiner , Andrew Morton , Chengming Zhou , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: D7FB44001F X-Rspam-User: X-Stat-Signature: w98rj55wt6gsa1httt46akn6g9bqk4zh X-Rspamd-Server: rspam03 X-HE-Tag: 1706632293-608454 X-HE-Meta: U2FsdGVkX18yBw3aZhf7BvFJDPZFF/++7khGeLrOPwpWiD2FvgL6Iq4i+wEAu/q4/V2hwkdI48V9kSiYt5o0fFwIgDcZAjvmQVO3E1jUBXo9cJ06UsiV6P1kCX/H4MG5JNp+4AUsfpkukn/jCgxdQZhSZqs16WgX0xyqNcLMVmveghVK7In7BxOlnc2ATCp5FDGpGktXFth3pEKVDqf6w1LJxmdzUHJbP9MuuRG2K5AAZETxn38Y2Cef8o1Rv/rNV7dt6mIjWmv+/6YAINMCsqigROMfxEm5ucTmOUBO3HMepJL8occVDUaKiP2BjV2E9S4qO1hd8zGlozRvb10pHRlLOyjFI1J9vpXl47ZQ5nvv3QDVZJhp58RxEOnG2XV17DsilWK3F7S4XzquFNLOjX4dAFJuiMHa+Yj1MqbXlu5v2B9vzG6iiE4fu1UEi4w4sXrur8kl0OvqONcbx6PS0NRmEfff371o+p7jqX1+ZXhGAJjdALr6dkmhQ9J6CA9AAl+00CnT7hGhCwT2hI1VtXtnZN9HukIcTiy+TpmmumJNDYCMAwtY5iSa7vofPvbIa1owWEd2tWK9kNt7Vl+lK+8mBYy2fnhUIknaLBxfjNUA4/zN2QQemyib9jU6O+k7X6DOGyaeOqrGq83a+x30Za3CVRX/Ke0Z8kxb9HqGTIxVNIpRRQw23vY7+97GqK3ST4g21kyzAMqz8776JKCG/uv0Xoh3F0SGjrQfHa1V6btXWUMx3vxfFqLyExQdKrdqQfs6eiICoLPhlF+YymBqjIvHknGawEMGbw1Rt68W3MSdUmGIaFDa9c992h4AQZ1Geqw1jlaOs3vBuKHwWLbjwAiviTRzoQQfSVMK1Zfjnup6d8dOHsawEhhpMECZx7yBnNCdKgrn6hFaXu+RYXLuwmq9k4ezalteGjB3Ge0uZeTZ3y/MpaJkCk1NTXMf5pQpg2sivTiYznWKsU6HVBd mLnpX17L 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000193, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jan 29, 2024 at 11:51=E2=80=AFPM Yosry Ahmed 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 > > --- > > 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 *e= ntry) > > 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 :) > > > static void zswap_entry_put(struct zswap_entry *entry) > > { > > - int refcount =3D --entry->refcount; > > - > > - WARN_ON_ONCE(refcount < 0); > > - if (refcount =3D=3D 0) { > > + WARN_ON_ONCE(!entry->refcount); > > + if (--entry->refcount =3D=3D 0) { > > WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode)); > > zswap_entry_free(entry); > > } > > -- > > 2.43.0 > > Reviewed-by: Nhat Pham