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Sun, 08 Feb 2026 13:59:14 -0800 (PST) Received: from localhost ([2a03:2880:10ff:8::]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-66d391ae639sm4737086eaf.7.2026.02.08.13.59.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Feb 2026 13:59:12 -0800 (PST) From: Nhat Pham To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, hughd@google.com, yosry.ahmed@linux.dev, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, len.brown@intel.com, chengming.zhou@linux.dev, kasong@tencent.com, chrisl@kernel.org, huang.ying.caritas@gmail.com, ryan.roberts@arm.com, shikemeng@huaweicloud.com, viro@zeniv.linux.org.uk, baohua@kernel.org, bhe@redhat.com, osalvador@suse.de, lorenzo.stoakes@oracle.com, christophe.leroy@csgroup.eu, pavel@kernel.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-pm@vger.kernel.org, peterx@redhat.com, riel@surriel.com, joshua.hahnjy@gmail.com, npache@redhat.com, gourry@gourry.net, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, rafael@kernel.org, jannh@google.com, pfalcato@suse.de, zhengqi.arch@bytedance.com Subject: [PATCH v3 15/20] zswap: do not start zswap shrinker if there is no physical swap slots Date: Sun, 8 Feb 2026 13:58:28 -0800 Message-ID: <20260208215839.87595-16-nphamcs@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260208215839.87595-1-nphamcs@gmail.com> References: <20260208215839.87595-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam11 X-Stat-Signature: nqu4apztznr7wf4mnkxptfbfjdqfdkd6 X-Rspam-User: X-Rspamd-Queue-Id: ED808140008 X-HE-Tag: 1770587954-938493 X-HE-Meta: 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 sXVz0fsv YIBTg+VvafralhybXfoZ5PUPB2Onbse+UpExqHVXR5bYc+4LRe9rzy1E9PjTTIjqJmTCbW7hCrW4rpooxtQDRqoLfWkhueNVbA1LDyu2jpmzSsIUicFZv0MO2b3w4IE2wwy3PzdbqG45jTbjryOcw36seVGK1if6hDYK8Hc2L5RtR9zTodXnrffYGAiaVDO/wPId1NU6yk/mcI6iMEsX2H9iiqvAj+DLY4MqD6EXZYVz/BMiDTUwZIPdAOSTxsp1gWLtQPvI/d4/EQ2CZShdjRaAAOipe5yWFgA4YjR/YqWB1ZZA1XnvY+FzR5gO6/HKmL7hETR78j4BLrIsI4Ta3ZHEV2GOApFEO/QNTEOpNZZ+XZMWq/t90SZt3/9lQjOurMqLPElWReQI4sBXKWO/5MKCScHmDOGSQnn28E5cai4kiAwXZd3N8dioeEuxiLDYr53n8vLvbfrJJqtXXoeZ5JPh8s5xG0bNjt9UqsiSS7/mzOd6cSnSGc82atWPYK5FO04mYMZEWv1/MTGL77YshMRWl6RrTqinhr7gQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 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 -- 2.47.3