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b=Dsr9B/z9s78VL5L7neUWaTmYTGAzKs/+9wdBC94e9KNSSSzbdgTMp4i7OmDCKTVJ9B Xo4Q+TGNfC7GcPKSAsWsvx/87+t0oHOltzsaRz2OWGbay8xKT8HI4VdRmPepC4WLeQVC GTxUbqCuvhHUMeGRfts5G4aqeN4QguTb/aCEwVr3GU0vpjMFGFJIOFsd/KdVfgjAkPUz Ar7QQLWYOyoUdeIUxtXvVcsUCVqlk7i85MrQc0+GdVTLE728LBZCfqkZ8Wr/lu0eq7+J pjFOAzRf11UCV56Sh1ymklAB9xxkuZtzATxFBF3OYJviBQCjSAp/n6RrgHQj2Z/wvOJu dIyA== X-Gm-Message-State: AFuF++mZjhSjhH7FQ4tH7VqlJV9Ihpf4e/oiyyV7Ti8uELvOl5Hg5qMD l3XjZ6idV/oGvdOJbuZznW1rDf20yGLK3dse2LxMHokHkLxPVbtQMV8kzsfF/mY/FFEZUjvZUwA 2WCzTVBYyRQ== X-Received: from plbkb13.prod.google.com ([2002:a17:903:338d:b0:2d3:768a:b66c]) (user=wfelipe job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:2392:b0:2d0:cc92:f7a3 with SMTP id d9443c01a7336-2d707a53a0fmr241134785ad.2.1787802497345; Wed, 26 Aug 2026 20:48:17 -0700 (PDT) Date: Thu, 27 Aug 2026 03:47:40 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.887.g758fc8c411-goog Message-ID: <20260827034807.2822234-1-wfelipe@google.com> Subject: [PATCH v3 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-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E0F5B20008 X-Stat-Signature: u8s9jjbocscxbhr3zurm4apa5szsac1o X-HE-Tag: 1787802498-454967 X-HE-Meta: U2FsdGVkX19aIDIVfbIW5zBKQC2PV0cwZoxECKbe6LXPQzzOgP9iajzRBTUpzxdKWjP+CVyW+CGyLGqcho/Fg//KJ19m6seePDA6oIbiKCW33B4qcU+UA59AoSE6rPdCQvlsiM2PtH8D3x1LkCGpprRTXYmHGomrob0ge4BTzItl6Cvqc34cgO+OQkkLY/htSPjtG+Ajsru+SOt/LWk8Kxo7ppEoTms3+xhiGS0TlAVS740CW4tzqT3ZaoyoGFImydeZVRgnwfB8bwbhVVQ6ZghWRz/onbXs8dN1YVvGt3a9LqVFE758oplz0x8dok4Jflu1N70zAZiFDU7frwz+fdqiwoI9vo+pJB05GPw9GogvPwIN6ifVhFe4Yqaavl6hQXRv+bdTLKaCXxuXJ8NDiZ0FHL9VpFk3xyNtcT0kWrlHRFwzpxSpZO3Xr5/FpFtPPsmBGN+rpqpC6dpP/7fae+Nb/otC8BzZn+iNJaxdVpMM9Vy8mSOzP2y56es/XMAxoVvzMl57V6ANyeFRs04aRVw4YR04Lis4dJioj4jf/Abcgz6HvnEi2Cf2ssVNIP5YjQGJkV8HBujuCR4B8qprjsCI2gemkE05KtMYTYLblMvyVCUCGRRxuGjAUMmY0N8TKSf+t1MH2sI7iMuSYQZ2RDLrdZy/Y/yN+jvVBOG/S0lLJYaEJDOhJuoE3lyw7tb5dhZv/kuDmYxHoTGzCjylHK8/YluT9KY9OCatk7wSnQhVr8E1KKuUwezv3wiITDxgyu5rjrkORfs6X/08FwVISJ6fsflSobEhSBcJUqRu9WJo2ByaNTd1VvGh+XbepLU0ZTVha/vH0dbyqTOHa9NHgMsYYwzYZagcgLw1Dv65/pt7HpL7X289ncND5J3KTeXA+nKhtUkP8Dk1Ryor3u78M9HXi2RdV97VHhGlBO9VspXAuk/gTqilol3e8bZC995cuXVAC4aKWDwyOnQILoY d+wQd1N+ 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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. 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). 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 | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) --=20 2.55.0.887.g758fc8c411-goog