From nobody Sun May 10 10:32:58 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BD38C433EF for ; Thu, 5 May 2022 15:59:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1381535AbiEEQDS (ORCPT ); Thu, 5 May 2022 12:03:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239474AbiEEQDQ (ORCPT ); Thu, 5 May 2022 12:03:16 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2A28515A3; Thu, 5 May 2022 08:59:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651766377; x=1683302377; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=4xPb5hYDEuqAvEmIzib3MGbfqSg4B/cO3p6boPn/ylU=; b=BqTAWosly3ieVB3EZ002q1J4C6FzRvEhir7aYD3yAz0ULz7ABCIUvE2K gPoHyCMbH46bfeCHIJ2IIYI9Rww/tkEkLM2BxtnahN95GJTNgRiEpc1bA aCX3YIUZiTRd9OkD6B7EL6NbahdpEMmTJSUJ10IX4e9yyej54zvTITZK6 bRh6Uvi5iVdA/FzIuvCjIS7ODRxKJH97RGyD0z+ekqEVp/oQIoD5Fwt+P YN2SPXyTu3tNNekoZWHMwYxDpvndODyT1VXixRPqBSw1Sfd8wXD94GZ/K 4D+2hguwzUuJCZLhwRGunUT83PEV44jKg/PunNEhpj7pZ+c125e1izWDw w==; X-IronPort-AV: E=McAfee;i="6400,9594,10338"; a="267756537" X-IronPort-AV: E=Sophos;i="5.91,201,1647327600"; d="scan'208";a="267756537" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2022 08:52:27 -0700 X-IronPort-AV: E=Sophos;i="5.91,201,1647327600"; d="scan'208";a="585394297" Received: from zq-optiplex-7090.bj.intel.com ([10.238.156.125]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2022 08:52:26 -0700 From: Zqiang To: paulmck@kernel.org, frederic@kernel.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] rcu: Add rnp->cbovldmask check in rcutree_migrate_callbacks() Date: Thu, 5 May 2022 23:52:36 +0800 Message-Id: <20220505155236.1559619-1-qiang1.zhang@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Currently, the rnp's cbovlmask is set in call_rcu(). when CPU going offline, the outgoing CPU's callbacks is migrated to target CPU, the number of callbacks on the my_rdp may be overloaded, if overload and there is no call_rcu() call on target CPU for a long time, the rnp's cbovldmask is not set in time. in order to fix this situation, add check_cb_ovld_locked() in rcutree_migrate_callbacks() to help CPU more quickly reach quiescent states. Signed-off-by: Zqiang --- kernel/rcu/tree.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 9dc4c4e82db6..bcc5876c9753 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4577,6 +4577,7 @@ void rcutree_migrate_callbacks(int cpu) needwake =3D needwake || rcu_advance_cbs(my_rnp, my_rdp); rcu_segcblist_disable(&rdp->cblist); WARN_ON_ONCE(rcu_segcblist_empty(&my_rdp->cblist) !=3D !rcu_segcblist_n_c= bs(&my_rdp->cblist)); + check_cb_ovld_locked(my_rdp, my_rnp); if (rcu_rdp_is_offloaded(my_rdp)) { raw_spin_unlock_rcu_node(my_rnp); /* irqs remain disabled. */ __call_rcu_nocb_wake(my_rdp, true, flags); --=20 2.25.1