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Wed, 18 Mar 2026 15:30:19 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:58::]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-67c0d88c5bbsm2544446eaf.10.2026.03.18.15.30.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 15:30:18 -0700 (PDT) From: Nhat Pham To: kasong@tencent.com Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, apopple@nvidia.com, axelrasmussen@google.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, bhe@redhat.com, byungchul@sk.com, cgroups@vger.kernel.org, chengming.zhou@linux.dev, chrisl@kernel.org, corbet@lwn.net, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jannh@google.com, joshua.hahnjy@gmail.com, lance.yang@linux.dev, lenb@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, mhocko@suse.com, muchun.song@linux.dev, npache@redhat.com, nphamcs@gmail.com, pavel@kernel.org, peterx@redhat.com, peterz@infradead.org, pfalcato@suse.de, rafael@kernel.org, rakie.kim@sk.com, roman.gushchin@linux.dev, rppt@kernel.org, ryan.roberts@arm.com, shakeel.butt@linux.dev, shikemeng@huaweicloud.com, surenb@google.com, tglx@kernel.org, vbabka@suse.cz, weixugc@google.com, ying.huang@linux.alibaba.com, yosry.ahmed@linux.dev, yuanchu@google.com, zhengqi.arch@bytedance.com, ziy@nvidia.com, kernel-team@meta.com, riel@surriel.com Subject: [PATCH v4 15/21] zswap: do not start zswap shrinker if there is no physical swap slots Date: Wed, 18 Mar 2026 15:29:46 -0700 Message-ID: <20260318222953.441758-16-nphamcs@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260318222953.441758-1-nphamcs@gmail.com> References: <20260318222953.441758-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: oydbjodrfg3qobme7rq4w9qxpyobfka6 X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 352C8160003 X-HE-Tag: 1773873020-560992 X-HE-Meta: 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 2J6mim4e 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When swap is virtualized, we no longer pre-allocate a slot on swapfile for each zswap entry. Do not start the zswap shrinker if there is no physical swap slots available. Signed-off-by: Nhat Pham --- mm/zswap.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index c5e1d252cb463..9d1822753d321 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1211,6 +1211,14 @@ static unsigned long zswap_shrinker_count(struct shrinker *shrinker, if (!zswap_shrinker_enabled || !mem_cgroup_zswap_writeback_enabled(memcg)) return 0; + /* + * When swap is virtualized, we do not have any swap slots on swapfile + * preallocated for zswap objects. If there is no slot available, we + * cannot writeback and should just bail out here. + */ + if (!get_nr_swap_pages()) + return 0; + /* * The shrinker resumes swap writeback, which will enter block * and may enter fs. XXX: Harmonize with vmscan.c __GFP_FS -- 2.52.0