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b=X5yvvNNVipj0+neA6goBlze68+8yx4VxmCessC1cBVwN/ShvOQZ8b8fSTZpV5Q74+B f1O1c4TDK6/7V5l+Wkdvfb0Vp0Bm1kPc3Tp3WCranaP/XHtZ3BHcojZurQcyr+SGNCnG +oprYS8sSUNvyND9JvWw3EyifZiKubnBe1SOk/FvlOCiIwTzgc1UeVg7JNbS249RtTO2 gRwTJBAzb8sTH98bma0CRyOofhywnjK2SNVjW4Rb04nwZpGmfFRo2/mH1EfFfKK1pTvX HJMAtI6fU7vPje5OhoYzAXnW5aAtKhk9TOdISktxi/sIM9o/bmf24+1hF26+NGLor76M 94/Q== X-Gm-Message-State: AFuF++nsL+VP2DCWDYc1nZonCdaEJc0Xwsx77CwQnUN3PAECy1brgWDD 1mTjTdg7RPzy+0SV0O4X7C9EcqhzcwUgshySoW71cQhNyidKcR7YuDlF7a5UbPArGdh8ZPKmAj/ ipdtBmMDdeQ== X-Received: from pld16.prod.google.com ([2002:a17:903:3550:b0:2ca:ceab:34a3]) (user=wfelipe job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:9cc:b0:2d3:716e:e2ae with SMTP id d9443c01a7336-2d74dc5f3f5mr61909945ad.6.1787888264856; Thu, 27 Aug 2026 20:37:44 -0700 (PDT) Date: Fri, 28 Aug 2026 03:37:30 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.897.gb25b4bd76c-goog Message-ID: <20260828033741.2184560-1-wfelipe@google.com> Subject: [PATCH v4 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: rspam11 X-Rspam-User: X-Stat-Signature: chsnrni6bjesstjr7pzctigcm747ajct X-Rspamd-Queue-Id: 77A0AC0005 X-HE-Tag: 1787888266-996121 X-HE-Meta: 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 PFkA0Co7 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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. v3 -> v4: - Patch 2: Use `long long` for `delta` and `max_delta` to avoid integer overflow 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). 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/test_zswap.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --