From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.40 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792739294; b=Ctya/ahmQiOWMXLUa8yg3K39B3NWdCJ006PKr8O9FoIoPWwXqIZOnguAfIZ11eBztigL 3SToJNUcPwh5c53AcAPOw8+/Vs8n80X95KbxDzydwvvLN6avNxnrfb1wkFkbP7aS8C/Me sTDLEqvigoi4tJsLU+5UmjXCXdxGCw3a/3qWeZ0baOjAVQA3JPJJ1CkfSNo2saiwXm2L0 EopCBrnLc0VUGjCXmKlhn0ydtw0xjYWpCFG2jHWbOJUMvrVtQ33HOz+YlFA+cJVxYe9nD j7r2nL5D4rEP1CBRUd94rNM3KLYlAOpT7LeRVd1+lXexE9OxRHyXbK6Olm6+KZX9P0w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792739294; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=7Bi9zppZM2yD7mKvBKUrbEl0+w7X4vbpIcDv6FIEg8c=; b=elAGYIIG9m7TS9RlQlkXDoCEarc+e3dxEnLYCFeisHu8bIksum8iOrx3go7dItHoFD+j 9pqYIfpThSmvf60GcN8gxQfbFDR0nNyzz87ykBbtllMCQquPhxlsqA8p6zeJkUii8AjRB EW3f4TVHFOsZSWzV/4DbdXbVHe9zY+2ukVMf7vd8652x9iP5ibvHjM9ai5NvueiUN8+hu 0NPyrmVRN8QAikX2hEfksgty6Fi1asLwKSzdW2I5KRNsuCzS8CbvRpJk9PT/SH+mBWgku Nfnczjyqo7iy1oIeZOvjEsV3emIhy9klHG1PV2rJo4Uv7kwECV4ZgQecq7YOE3+D+UQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=BfVmx2X2; arc=none smtp.remote-ip=91.218.175.40 Received: from mta0.migadu.com (out-40.mta0.migadu.com [91.218.175.40]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4B27B606A31A for ; Fri, 23 Oct 2026 07:08:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 4B27B606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=BfVmx2X2 X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=pAq3+l4oQM0fA1DixnIYuWfCLcca2gf22KdWyl5gugU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792739290; v=1; x=1793344090; b=BfVmx2X2no0q+x03VvQeQWxeu/iN3eilcKjpyVvq5L7XlcnMpxGwGQIJGBfq+Ig7qU0GbB47 8nfym7Pvpz79jCjRzm51rP395RH38wgMeyQmwTivmfgPwJk1KTq88LjG4x6xoCzkcLs2wvHkjH5 49dfSBzBwmLCHr72bFyHTg2c= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id f7e879e1153112cc; Fri, 23 Oct 2026 07:08:10 +0000 X-Mizu-Trace-ID: f7e879e1153112cc X-Migadu-Flow: FLOW_OUT Message-ID: Date: Fri, 23 Oct 2026 15:07:59 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH-next 3/6] cgroup/cpuset: Fix incorrect effective_cpus bug in update_cpumasks_hier() To: Waiman Long , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Shuah Khan Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Guopeng Zhang References: <20261022031643.1351877-1-longman@redhat.com> <20261022031643.1351877-4-longman@redhat.com> From: Ridong Chen In-Reply-To: <20261022031643.1351877-4-longman@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/22/2026 11:16 AM, Waiman Long wrote: > With the introduction of cpuset.cpus.exclusive, the computation of > effective_cpus differs depending on if a cpuset is a valid partition > root or not. > > In update_cpumasks_hier(), effective_cpus is computed early > to check if the current subtree can be skipped. Later on > update_parent_effective_cpumask() may be called which can change the > partition state from valid to invalid or vice versa. If the partition > state changes, the previously computed effective_cpus may no longer be > valid. Fix that by recomputing effective_cpus again when that happens. > > Also add a new test case into test_cpuset_prs.sh to verify this change. > > Fixes: e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2") > Signed-off-by: Waiman Long > --- > kernel/cgroup/cpuset.c | 10 ++++++++-- > tools/testing/selftests/cgroup/test_cpuset_prs.sh | 3 +++ > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index db6e4663f4be..7b9062326f35 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -2316,10 +2316,16 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, > if (update_parent) { > update_parent_effective_cpumask(cp, partcmd_update, NULL, tmp); > /* > - * The cpuset partition_root_state may become > - * invalid. Capture it. > + * Capture current partition_root_state as it may have > + * changed. Recompute effective cpumask if changed. > */ > new_prs = cp->partition_root_state; > + if (new_prs != old_prs) { > + if (new_prs > 0) > + compute_partition_effective_cpumask(cp, tmp->new_cpus); > + else > + compute_effective_cpumask(tmp->new_cpus, cp, parent); > + } > } > If cs is a partition (remote or local), we call compute_partition_effective_cpumask to compute the effective cpumask; otherwise we should call compute_effective_cpumask. Wouldn't it be better to call compute_partition_effective_cpumask whenever cs is a valid partition, so we can eliminate the branch outside? ``` static void compute_effective_cpumask(struct cpumask *new_cpus, struct cpuset *cs, struct cpuset *parent) { bool has_cpus; if (is_remote_partition (cs) || (is_partition_valid(cs) && is_partition_valid(parent))) return compute_partition_effective_cpumask(cs, &new_cpus); has_cpus = cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus); if (!has_cpus && is_in_v2_mode()) cpumask_copy(new_cpus, parent->effective_cpus); } ``` > spin_lock_irq(&callback_lock); > diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > index 47791591002f..8595b6b4b7bf 100755 > --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh > +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > @@ -364,6 +364,9 @@ TEST_MATRIX=( > " C1-4:X2-4 C2-4:X3-4:P1 C3-4:X4:P2 \ > . . X5 . . 0 A1:1-4|A2:2-4|A3:3-4 \ > A1:P0|A2:P-1|A3:P-2 ." > + " C1-5:X3-5:P2 C3-5:X4-5:P2 C4-5:X5:P2 \ > + . X1-4 . . . 0 A1:1-3|A2:4|A3:4 \ > + A1:P2|A2:P2|A3:P-2 1-4" > " C1-4:X2-4 C1-4:X3-4:P1 C3-4:X4:P2 \ > . . . X1 . 0 A1:1-2|A2:3-4|A3:3-4 \ > A1:P0|A2:P1|A3:P-2 ." -- Best regards Ridong