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[34.127.51.67]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df6a5a4997sm19710685ad.27.2026.09.23.21.27.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 21:27:31 -0700 (PDT) From: Hui Peng To: Waiman Long , Ridong Chen , Guopeng Zhang , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: Shuah Khan , Chen Ridong , cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hui Peng , stable@vger.kernel.org Subject: [PATCH v4 1/3] cgroup/cpuset: return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict Date: Thu, 24 Sep 2026 04:27:27 +0000 Message-ID: <20260924042729.1908863-2-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.310.g51773c2048-goog In-Reply-To: <20260924042729.1908863-1-benquike@gmail.com> References: <20260924042729.1908863-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When a remote partition is created underneath an existing local partition via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees parent->partition_root_state =3D=3D PRS_MEMBER and calls remote_partition_enable(). Commit 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning and proceeds to enable the remote partition on CPUs that are already owned by the ancestor local partition in subpartitions_cpus. This can be reproduced on Linux 7.3.0-rc3 with: mkdir -p /tmp/cg1 mount -t cgroup2 none /tmp/cg1 echo "+cpuset" > /tmp/cg1/cgroup.subtree_control mkdir /tmp/cg1/A echo 1 > /tmp/cg1/A/cpuset.cpus echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive echo root > /tmp/cg1/A/cpuset.cpus.partition echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control mkdir /tmp/cg1/A/B echo 1 > /tmp/cg1/A/B/cpuset.cpus echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control mkdir /tmp/cg1/A/B/D echo 1 > /tmp/cg1/A/B/D/cpuset.cpus echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition which triggers: WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x3= 00 and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions claiming exclusive CPU 1. Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects subpartitions_cpus in remote_partition_enable(), matching the error code used by remote_cpus_update() for the same subpartitions_cpus conflict, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in= exclusive CPUs") Suggested-by: Guopeng Zhang Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- kernel/cgroup/cpuset.c | 3 ++- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 2538faac9aba..7381fa8502e7 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1591,10 +1591,11 @@ static int remote_partition_enable(struct cpuset *c= s, int new_prs, * above it or remote partition root underneath it is not allowed. */ compute_excpus(cs, tmp->new_cpus); - WARN_ON_ONCE(cpumask_intersects(tmp->new_cpus, subpartitions_cpus)); if (!cpumask_intersects(tmp->new_cpus, cpu_active_mask) || cpumask_subset(top_cpuset.effective_cpus, tmp->new_cpus)) return PERR_INVCPUS; + if (cpumask_intersects(tmp->new_cpus, subpartitions_cpus)) + return PERR_NOCPUS; if (((new_prs =3D=3D PRS_ISOLATED) && !isolated_cpus_can_update(tmp->new_cpus, NULL)) || prstate_housekeeping_conflict(new_prs, tmp->new_cpus)) diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/test= ing/selftests/cgroup/test_cpuset_prs.sh index 3f7e81709365..b732078bf319 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -298,6 +298,8 @@ TEST_MATRIX=3D( " C0-4:X2-4 C1-4:X2-4:P2 C2-4:X4:P1 \ . . . X1 . 0 A1:0-1|A2:2-4|A3:2-4 \ A1:P0|A2:P2|A3:P-1 2-4" + " CX1-3:P1 CX1-3 CX1-3 . . . P1 . 0 A1:1-3|A2:= 1-3|A3:1-3 \ + A1:P1|A2:P0|A3:P-1" =20 # Remote partition offline tests " C0-3 C1-3 C2-3 . 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[34.127.51.67]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df6a5a4997sm19710685ad.27.2026.09.23.21.27.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 21:27:32 -0700 (PDT) From: Hui Peng To: Waiman Long , Ridong Chen , Guopeng Zhang , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: Shuah Khan , Chen Ridong , cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hui Peng , stable@vger.kernel.org Subject: [PATCH v4 2/3] cgroup/cpuset: prevent activating local partition over remote one Date: Thu, 24 Sep 2026 04:27:28 +0000 Message-ID: <20260924042729.1908863-3-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.310.g51773c2048-goog In-Reply-To: <20260924042729.1908863-1-benquike@gmail.com> References: <20260924042729.1908863-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Commit 6da580ec656a ("cgroup/cpuset: Don't allow creation of local partition over a remote one") added a check in update_prstate() to reject creating a top-level local partition whose cs->exclusive_cpus intersects subpartitions_cpus. However, if a top-level cgroup A1 has a child A1/A2 enabled as a remote partition on a subset of its exclusive CPUs (X2-3 on A1, CX2-3:P2 on A1/A2), and A1 is then set to "root" (P1, becoming "root invalid" via update_prstate() because its exclusive CPUs intersect subpartitions_cpus) followed by expanding its CPUs to include additional non-remote CPUs (CX1-3), update_cpumask() / update_exclusive_cpumask() calls validate_partition() without going through update_prstate(). Because validate_partition() does not check trialcs->exclusive_cpus against subpartitions_cpus, A1 transitions from "root invalid" to a valid local partition over the existing remote partition A1/A2 and triggers: WARNING: kernel/cgroup/cpuset.c:1943 at update_parent_effective_cpumask+0= x189b/0x1fd0 Check trialcs->exclusive_cpus against subpartitions_cpus in validate_partition() when !is_partition_valid(cs), and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 6da580ec656a ("cgroup/cpuset: Don't allow creation of local partitio= n over a remote one") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- kernel/cgroup/cpuset.c | 4 ++++ tools/testing/selftests/cgroup/test_cpuset_prs.sh | 2 ++ 2 files changed, 6 insertions(+) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 7381fa8502e7..7c5b4a8f1f3a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2415,6 +2415,10 @@ static enum prs_errcode validate_partition(struct cp= uset *cs, struct cpuset *tri if (cpumask_empty(trialcs->effective_xcpus)) return PERR_INVCPUS; =20 + if ((parent =3D=3D &top_cpuset) && !is_partition_valid(cs) && + cpumask_intersects(trialcs->exclusive_cpus, subpartitions_cpus)) + return PERR_REMOTE; + if (prstate_housekeeping_conflict(trialcs->partition_root_state, trialcs->effective_xcpus)) return PERR_HKEEPING; diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/test= ing/selftests/cgroup/test_cpuset_prs.sh index b732078bf319..4a451350ad84 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -321,6 +321,8 @@ TEST_MATRIX=3D( " C1-3:P2 X4:P2 . . . X3:P2 . . 0 A1:1-2|XA1= :1-3|A2:3:XA2:3 A1:P2|A2:P2 1-3" " C0-3:P2 . . C4-6 C0-4 . . . 0 A1:0-4|B1:= 5-6 A1:P2|B1:P0" " C0-3:P2 . . C4-6 C0-4:C0-3 . . . 0 A1:0-3|B1:= 4-6 A1:P2|B1:P0 0-3" + " X2-3 CX2-3:P2 . . P1:CX1-3 . . . 0 A1:1|A2:2-= 3|XA2:2-3 \ + A1:P-1|A2:P2 2-3" =20 # Local partition invalidation tests " C0-3:X1-3:P2 C1-3:X2-3:P2 C2-3:X3:P2 \ --=20 2.49.0 From nobody Thu Sep 24 13:37:13 2026 Received: from mail-pj2-f13.google.com (mail-pj2-f13.google.com [74.125.227.141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4899836F434 for ; Thu, 24 Sep 2026 04:27:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.141 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790224055; cv=none; b=rdcfNBI64xE8IEuxRhRFVevsd1Bi7uDhWf4//fRgW5rHkTgGoYtO6o9/Xmpdt8HG03cSPrioZpBZcuc0oL5L04zb9jGnbEwmz5y3y1p7LOFKNnkUi87xLIr3P933PrEy2h3PXng8/0inxOhWPK6FnzVOmNSRkn7LeiY9PmOcT+w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790224055; c=relaxed/simple; bh=SlPzGPDevJ712yV3K8dLA8Akc44d66oXNW6JLxeKPxg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gSRs4H26qXHpIVznEHD6fJBdM3Owxm48441e8Cjzfvu3uK8lV4cvsr6pifXi2vYvUmH1wmPsdJhIoTR9irF3zU5GwOzjANNgApDhva8rTO+kkhuMlQ+CHS3WOGPW3DXooVPnV71+sz2N85Iu31pL04H7SNZ+s6jiXTmh+5ziO1s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=MR2PlY+h; arc=none smtp.client-ip=74.125.227.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MR2PlY+h" Received: by mail-pj2-f13.google.com with SMTP id d9443c01a7336-2dd88a115ebso10013535ad.2 for ; Wed, 23 Sep 2026 21:27:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1790224053; x=1790828853; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=dF6lxsisMCHm/KxhSC1onb0PhKT95yZ7vVRGieeLH5c=; b=MR2PlY+haYYzIFjabcl3HIPSmBOFopJfZpkMUrd5tIrFmuoOdT/QKNp5mPzvpVfNgZ ck4DOOH8HhQ+l50epqiUcqMmggFbcU2RAQnXCWeqf1YOu2M12EdZW3sDv+voJm3/yXa1 lHGCXBtcyT9Ttwcs25vJFpYdUBzd7QFEHLh3Gr+liLau8VxDgmPI+RK+SfExHiYHGzh1 pvG6Enk5ggT+xdlYAuR0foDzCPqzhmWAFioOCaKMWOy6EZN20X4epoSRroQw6jwAZd3/ kpv1tPoPSry5nXA2Chcfn39m+k655KPVFoHXq88a2QSCAIyeWpZoLsjZXHt9OnRhPtAU zPyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790224053; x=1790828853; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=dF6lxsisMCHm/KxhSC1onb0PhKT95yZ7vVRGieeLH5c=; b=TXEWQAcxkJx9Q+8HnPpWpFQQ6oy2wXoctagl1VNMdNCR4Ycx5Zpg2u4kuUlGhQLNHn JEspuVF3WxFmld9TFNiszqhonaGNyrz30hvS0lnzmRn0z0gyRW5mYT47P05GCRyFfmOa mPad7y1AB6MKoi2zqt1tOculEDLlxd6remYSnx4gcinLR89MlfBewXJGzGKejwNF0kjM 8XQNYpohfsszfaT++VfbPI0uh/WG/UyOmpz8KZJt8mWwNfWpMNoIwCl0cRV9LLox4VLV wlo9zgOqohBC3qIrI26fDOOa8EMsHhIcYWbs7OpfHkioTDwsF4xE22U8CuleGSj2TdQZ D0nA== X-Forwarded-Encrypted: i=1; AKwUvBypL9h0/PW5EEtrNzRfgTrxiSddgfv/TOz/THbk6n68FJNTPB4+CfxJDci/J58mmC7maIKwP4nh1AyJGgg=@vger.kernel.org X-Gm-Message-State: AFuF++m8kgDjCLfxx7xcBnmq4u5BVEFBhuHSJxj22TxeqQ7idFyEEWNP WyJnp8sDkpVJxWc4i42Gn5Z0lZcweSAEQ00Y+SY/e1S4jTIKKPACNTJs X-Gm-Gg: AYBFou3HJcQX+YFOsdnqCNZ6QHJwCwTsAvCjYX+H2+d1eFTOjwEN6JZAfom+vzSHSYy /R0FPpPRPHd5trYYJLK+6Wwfx4cvIEGJPMqwTRrwVrnubwhN8keMfjywsxFYB/A/FWt/y1ZNbGl TlpUNDMDvlaKGnmH3rk3JPcZbA22VU7K2nQqT3ApdW5YGnuSAD5CHZPgNGaDjbERFmTfaPdqoLS TX3yyaHcOJqxybxgkjXN6ysk9Ttolm9gwgHqtK1a1WISIC7Nv5YoQgZRnsVfNUX0FLpm4uc9xUs nPKpACCyOX+px3tgB+TU9G430eZLpupoYAre1zN/ulPADtAdVD3LJJJvwejqThD3zi0P5i3YJ3k 3KYQLpAtqXT5iXCIujqKXW6gOONcSkKEM8AF9F6Lvy3AbyYjRszCXkq2Fsfkv3Se31OEdxwT7A0 nWlw7BefiajFifw/AxOpbIUK3sTsBW7xDSMJjwmdEdFgKhjGPY/0rys7e+25P5745ZtLMLxDsx4 b06iz96RArN/cgyNFwjZ8pkOmyc7SddO+qN2S3rHM18wjsk9fuDovVUaNhLiP0d1W5rd9ERKL1n 6YittizWRw== X-Received: by 2002:a17:902:d481:b0:2dd:b83b:fe1e with SMTP id d9443c01a7336-2df7de9309fmr10196965ad.22.1790224053300; Wed, 23 Sep 2026 21:27:33 -0700 (PDT) Received: from phui-2.c.googlers.com.com (67.51.127.34.bc.googleusercontent.com. [34.127.51.67]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2df6a5a4997sm19710685ad.27.2026.09.23.21.27.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 21:27:33 -0700 (PDT) From: Hui Peng To: Waiman Long , Ridong Chen , Guopeng Zhang , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: Shuah Khan , Chen Ridong , cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hui Peng , stable@vger.kernel.org Subject: [PATCH v4 3/3] cgroup/cpuset: check sibling effective_xcpus in cpus_excl_conflict() Date: Thu, 24 Sep 2026 04:27:29 +0000 Message-ID: <20260924042729.1908863-4-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.310.g51773c2048-goog In-Reply-To: <20260924042729.1908863-1-benquike@gmail.com> References: <20260924042729.1908863-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In cpus_excl_conflict(), when a valid local partition A1 uses implicit exclusive CPUs (cpuset.cpus set without cpuset.cpus.exclusive, so sibling->exclusive_cpus is empty while sibling->effective_xcpus is populated), a sibling cgroup B1 can still set cpuset.cpus.exclusive on the same CPUs because cpus_excl_conflict() only checks sibling->exclusive_cpus. Fall back to sibling->effective_xcpus in cpus_excl_conflict() when sibling->exclusive_cpus is empty, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 2a3602030d80 ("cgroup/cpuset: Don't invalidate sibling partitions on= cpuset.cpus conflict") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- kernel/cgroup/cpuset.c | 5 ++++- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 1 + 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 7c5b4a8f1f3a..f46a51f07938 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -713,7 +713,10 @@ static inline bool cpus_excl_conflict(struct cpuset *t= rial, struct cpuset *sibli return true; =20 /* Exclusive_cpus cannot intersect */ - return cpumask_intersects(trial->exclusive_cpus, sibling->exclusive_cpus); + return cpumask_intersects(trial->exclusive_cpus, + cpumask_empty(sibling->exclusive_cpus) + ? sibling->effective_xcpus + : sibling->exclusive_cpus); } =20 static inline bool mems_excl_conflict(struct cpuset *cs1, struct cpuset *c= s2) diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/test= ing/selftests/cgroup/test_cpuset_prs.sh index f4d1822d4e21..f62155cf6162 100755 --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh @@ -445,6 +445,7 @@ TEST_MATRIX=3D( =20 # Changes to cpuset.cpus.exclusive that violate exclusivity rule is rejec= ted " C0-3 . . C4-5 X0-3 . . X3-5 1 A1:0-3|B1:= 4-5" + " C0-3:P1 . . C4-5 . . . X3-5 1 A1:0-3|B1:= 4-5 A1:P1|B1:P0" =20 # cpuset.cpus.exclusive cannot be set to a superset of sibling's cpuset.c= pus " C0-3 . . C4-5 X3-5 . . . 1 A1:0-3|B1:= 4-5" --=20 2.49.0