From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.120 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793004600; b=fY/VtZuIHKncAQ4ZLw4jbmfdfNN2SY9QE07XCM7dMUZkvz2YqtJwonZrSnVHbyXPuhQO ZnA9MmyFfK0Sp6/az4r5c+c7E0wvT5n2p1gOCCgO0UHThUM5F2tCPDvYxTFOghKlSKWih 8wqC+Y3JAVXEZ0rZpLYeVGTa4i4fMz5rDvpVw7ll++mHVgVFurE51YuNGQjdgpnIMt1e4 EtLjlqsWJoBjPj0A07MSX3+9mO4pAprd6yi4aCcLgK1dU6OaO0jGFKtEh3+03VIYWVJxd PVz6VIDfF8KMmySEQCOKQC82mmdn+vRoHw64IQLtEKYG09FdSlTtCNWdUAjpY/Qby/Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793004600; 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:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=xTCncqWwkGyvWmFCnNOjI4Ctl5a4Y1hNNgZFEF7i6Sc=; b=Va2gzubKSdy/nMiIvsh09zzdqgUqofdumyTfQ3BSmrb2PdzXH12TxDoqtULvWTyqOR3T Cx8TzYTnsbUneCeNQkV0zdbBNhwS6N7L5G3vWg846hVRep9DpNKOn/9u5zi1LFqW7KVUM dzu5zXqhLnxqBhkgdO/q2+5sqe6/XyT/iWbCftkVMUxob/rU1sCFr1qlOWbShMqTN3Zcx nzwclij/aaH+oM+uBJLjA1hmuyjFyhWbOfvPv9g1Tx/GE2ob5A6pz5WiP4lLASPGFVcOC FK8n0r/5TQNuH2uQJzZa51MyYno7RD6aZ7JZNDdfv4vghWfKMEeLGaiybLwraOmTQ4Q== 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=Fcvbt7V2; arc=none smtp.remote-ip=91.218.175.120 Received: from mta0.migadu.com (out-120.mta0.migadu.com [91.218.175.120]) (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 A4484606A31A for ; Mon, 26 Oct 2026 08:49:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A4484606A31A 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=Fcvbt7V2 X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=aJ85KleHsdb6375xJChkcgqa/AGS2OmDzCxBgEDf+QY=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793004596; v=1; x=1793609396; b=Fcvbt7V2CoxVpw3hYaKc20x1nauvHcffAQmhCiSBDPlGF/NmM2kd4ly/D9/cTWMM+OhREaZm HPvmkpT2UNoi2ZOSaCjFZuSwHqdYaaJXZMKtO7grmILazMGiLYeaze2Z44D655UtpU/YpT7FlSy 77fKpKLUMid7BPCuJgxX9118= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 7f4f4f5d460e380d; Mon, 26 Oct 2026 08:49:56 +0000 X-Mizu-Trace-ID: 7f4f4f5d460e380d X-Migadu-Flow: FLOW_OUT Message-ID: Date: Mon, 26 Oct 2026 16:49:36 +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 v3 08/11] cgroup/cpuset: Release invalid isolated CPUs in compute_partition_effective_cpumask() To: Waiman Long , Ridong Chen , 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 References: <20261025214449.310715-1-longman@redhat.com> <20261025214449.310715-9-longman@redhat.com> Content-Language: en-US From: Guopeng Zhang In-Reply-To: <20261025214449.310715-9-longman@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 在 2026/10/26 05:44, Waiman Long 写道: > It is found by sashiko that when a child isolated partition with parent > root partition is invalidated in compute_partition_effective_cpumask(), > the switching of the isolated exclusive CPUs from child to parent will > not be reflected in isolated_cpus leading to CPU leakage. Fix that by > calling isolated_cpus_update() when that happens. > > Also simplify compute_partition_effective_cpumask() by doing > child partition invalidation only for the special case of no more > effective_cpus left in a populated parent. The other case doesn't > actually warrant invalidation at this stage and subsequent iteration > in update_cpumasks_hier() and update_parent_effective_cpumask() for > that child should handle that. > > Also drop the make_partition_invalid() helper by inlining it into > compute_partition_effective_cpumask() as it is the only caller. > > A new test case is add to test_cpuset_prs.sh to verify this. > > Fixes: 11e5f407b64a ("cgroup/cpuset: Keep track of CPUs in isolated partitions") > Signed-off-by: Waiman Long > --- > kernel/cgroup/cpuset.c | 46 +++++++------------ > .../selftests/cgroup/test_cpuset_prs.sh | 4 ++ > 2 files changed, 21 insertions(+), 29 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 53fa3970946e..6d224e614e74 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -254,15 +254,6 @@ static inline bool cs_is_member(const struct cpuset *cs) > return cs->partition_root_state == PRS_MEMBER; > } > > -/* > - * Callers should hold callback_lock to modify partition_root_state. > - */ > -static inline void make_partition_invalid(struct cpuset *cs) > -{ > - if (cs->partition_root_state > 0) > - cs->partition_root_state = -cs->partition_root_state; > -} > - > /* > * Send notification event of whenever partition_root_state changes. > */ > @@ -2153,8 +2144,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, > * or update_cpumasks_hier() where parent and children are modified > * successively, we don't need to call update_parent_effective_cpumask() > * and the child's effective_cpus will be updated in later iterations. > - * > - * Note that rcu_read_lock() is assumed to be held. > */ > static void compute_partition_effective_cpumask(struct cpuset *cs, > struct cpumask *new_ecpus) > @@ -2166,15 +2155,16 @@ static void compute_partition_effective_cpumask(struct cpuset *cs, > WARN_ON_ONCE(!is_partition_valid(cs)); > > /* > - * Check child partition roots to see if they should be > - * invalidated when > - * 1) child effective_xcpus not a subset of new > - * excluisve_cpus > - * 2) All the effective_cpus will be used up and cp > - * has tasks > + * Check child partition roots to see if they should be invalidated > + * when all the effective_cpus will be used up and cs is populated. > + * It is better to sacrifice a child partition root than invalidating > + * the whole subtree. > + * > + * Return early if the effective_cpus is already empty. > */ > compute_excpus(cs, new_ecpus); > - cpumask_and(new_ecpus, new_ecpus, cpu_active_mask); > + if (!cpumask_and(new_ecpus, new_ecpus, cpu_active_mask)) > + return; > > rcu_read_lock(); > cpuset_for_each_child(child, css, cs) { > @@ -2186,22 +2176,20 @@ static void compute_partition_effective_cpumask(struct cpuset *cs, > * partition root. > */ > WARN_ON_ONCE(is_remote_partition(child)); > - WRITE_ONCE(child->prs_err, 0); > - if (!cpumask_subset(child->effective_xcpus, > - cs->effective_xcpus)) > - WRITE_ONCE(child->prs_err, PERR_INVCPUS); > - else if (populated && > - cpumask_subset(new_ecpus, child->effective_xcpus)) > - WRITE_ONCE(child->prs_err, PERR_NOCPUS); > - > - if (child->prs_err) { > + if (populated && cpumask_subset(new_ecpus, child->effective_xcpus)) { > int old_prs = child->partition_root_state; > + int parent_prs = cs->partition_root_state; > > /* > - * Invalidate child partition > + * Invalidate child partition and update isolated_cpus > + * if necessary. > */ > spin_lock_irq(&callback_lock); > - make_partition_invalid(child); > + WRITE_ONCE(child->prs_err, PERR_NOCPUS); > + if ((old_prs == PRS_ISOLATED) && (parent_prs == PRS_ROOT)) > + isolated_cpus_update(PRS_ISOLATED, PRS_ROOT, > + child->effective_xcpus); > + child->partition_root_state = -old_prs; > spin_unlock_irq(&callback_lock); > notify_partition_change(child, old_prs); > continue; > diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > index f0d98da3cfd8..d7d0bef0a17a 100755 > --- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh > +++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh > @@ -518,6 +518,10 @@ TEST_MATRIX=( > " CX0-4:P2 CX2-4:P2 CX3-4:P2 . . X2 . . 0 A1:0-1,3-4|A2:2|A3:2 \ > A1:P2|A2:P2|A3:P-2 0-4" > > + # When an isolated partition child with root partition parent is invalidated, > + # its effective xcpus will be removed from isolated_cpus. > + " C1-4:P1 C3-4:P2 . . T:C3-4 . . . 0 A1:3-4|A2:3-4 A1:P1|A2:P-2 ." > + > # > # old-A1 old-A2 old-A3 old-B1 new-A1 new-A2 new-A3 new-B1 fail ECPUs Pstate ISOLCPUS > # ------ ------ ------ ------ ------ ------ ------ ------ ---- ----- ------ -------- Reviewed-by: Guopeng Zhang Tested-by: Guopeng Zhang Thanks, Guopeng