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Tue, 05 May 2026 08:39:30 -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, haowenchao22@gmail.com Subject: [PATCH v6 15/22] zswap: do not start zswap shrinker if there is no physical swap slots Date: Tue, 5 May 2026 08:38:44 -0700 Message-ID: <20260505153854.1612033-16-nphamcs@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260505153854.1612033-1-nphamcs@gmail.com> References: <20260505153854.1612033-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 3469680013 X-Stat-Signature: jgkuobgh9ryhd9s3r76ddcdqdoggdyjs X-Rspam-User: X-HE-Tag: 1777995572-87936 X-HE-Meta: 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 s11dWFRr 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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 e8aa9201ea30..751687b7e2b9 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1214,6 +1214,14 @@ 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