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b=PKdLCznUNvmoLEXURIe3C2Io56en/ndlC7EUq0Vox+Ad3Mw9eFb/A8LWbwDX6bFCLD BEzSADmzEkmLvEw9dqdlaKGVpSqZJobla+eZperJebIZgBD70V2x920Q7NvI/eQRqfVn q5+TbgSb3sRA1LiLPM/fkuDcr6uO2JIQi7m8eERqEs9eA2hALvktmnxI3ygmx0msH0zf X/cOGq3oeDhekfq8vkjRZ22npe3RmFlJcTlzvoK2GGksyxyNGdfVNrrwl2/ptIGS9urV QRyDwsXLMsyWWnIRPh42/sp53yXmRCBu0aPWSMTu6qVrENOUj71R3ikqnO/iSbRsW6pZ MHLA== X-Gm-Message-State: AFuF++lW49IGy29E4ZYUTn3QJBW0eB5+MxHs8SFtWuKy56MSUKe412jJ 0jNJgt76xjQGzHbAjRbxi3kmHnlh66Ox7ou/91RlnNzYwdT+EJEXWpgDck/Bb1ZkWTo3xeV13vM vJ/0kLaBOvQ== X-Received: from plbjy16.prod.google.com ([2002:a17:903:42d0:b0:2d9:1541:2cac]) (user=wfelipe job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ef52:b0:2d9:383a:30f1 with SMTP id d9443c01a7336-2d9383a326bmr129023445ad.4.1788240173018; Mon, 31 Aug 2026 22:22:53 -0700 (PDT) Date: Tue, 1 Sep 2026 05:22:26 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.970.g62bdec98f9-goog Message-ID: <20260901052250.154532-1-wfelipe@google.com> Subject: [PATCH v5 0/2] selftests/cgroup: fixes for test_zswap on single core VM From: Wilson Felipe Pereira To: Andrew Morton , Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , Tejun Heo , "=?UTF-8?q?Michal=20Koutn=C3=BD?=" , Shuah Khan Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Wilson Felipe Pereira Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 75B7D180002 X-Stat-Signature: nuhc4as8w377ycx1spa131pgrbz13qqw X-Rspam-User: X-HE-Tag: 1788240174-713950 X-HE-Meta: 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 KPBs54Q0 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This series fixes two test failures in test_zswap observed when running on a single-core VM (-smp 1) with 4GB of RAM. Patch 1 addresses a race condition in test_zswap_writeback() where waitpid() returns before the exiting child process is switched away by the kernel, causing an immediate write of "+memory" to cgroup.subtree_control to fail with -EBUSY. We fix this by waiting for cgroup.events to report "populated 0". Patch 2 fixes an implicit unsigned conversion bug in test_no_kmem_bypass() where small negative timing differences between debugfs stored_pages and cgroup zswapped bytes caused the comparison to falsely fail due to unsigned promotion. v4 -> v5: - Patch 2: Introduce `cg_read_key_long_long()` to return a `long long` value, and have `cg_read_key_long` use it and convert to `long`. - Patch 2: Make `zswapped` a `long long`. This prevents a overflow on 32-bit platforms (Andrew Morton, Sashiko). v3 -> v4: - Patch 2: Use `long long` for `delta` and `max_delta` and explicitly cast `stored_pages` to avoid integer overflow and implicit unsigned promotion warnings on 32-bit platforms (Andrew Morton, Sashiko). v2 -> v3: - Patch 1: Collect Acked-by from Michal Koutn=C3=BD. - Patch 2: Explicitly cast stored_pages to (long) in delta calculation and inline the return comparison (Michal Koutn=C3=BD). v1 -> v2: - Patch 1: Replace EBUSY retry loop with cg_read_strcmp_wait() waiting for cgroup.events "populated 0" (Michal Koutn=C3=BD). - Patch 1: Clarify task lifecycle in commit description (Yosry Ahmed). - Patch 2: Remove abs() and declare delta/zswapped as signed longs with a signed threshold comparison (Michal Koutn=C3=BD). - Patch 2: Add Fixes tag (Michal Koutn=C3=BD). v4: https://lore.kernel.org/all/20260828033741.2184560-1-wfelipe@google.com= / v3: https://lore.kernel.org/all/20260827034807.2822234-1-wfelipe@google.com= / v2: https://lore.kernel.org/all/20260824033533.2147900-1-wfelipe@google.com= / v1: https://lore.kernel.org/all/20260804042053.56940-1-wfelipe@google.com/ Wilson Felipe Pereira (2): selftests/cgroup: test_zswap: wait for cgroup to unpopulate in test_zswap_writeback selftests/cgroup: test_zswap: fix implicit unsigned promotion bug in test_no_kmem_bypass tools/testing/selftests/cgroup/lib/cgroup_util.c | 17 ++++++++++++--= --- tools/testing/selftests/cgroup/lib/include/cgroup_util.h | 1 + tools/testing/selftests/cgroup/test_zswap.c | 13 ++++++++----- 3 files changed, 21 insertions(+), 10 deletions(-) --