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Fri, 20 Mar 2026 12:27:59 -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 v5 15/21] zswap: do not start zswap shrinker if there is no physical swap slots Date: Fri, 20 Mar 2026 12:27:29 -0700 Message-ID: <20260320192735.748051-16-nphamcs@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260320192735.748051-1-nphamcs@gmail.com> References: <20260320192735.748051-1-nphamcs@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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