From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFE7F5D477; Sun, 24 Mar 2024 22:35:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711319719; cv=none; b=Wo925uK1cHg8gaJzdsHjGRaz4GOSlD+eHBlUBV9m6sQo010kY3Nq9pFh6oo5w4q+0k0iFlrVs0JZLO3FNFmd2xgH6rPqPn1Xk6L9jZHMrVAUSgdaCU4n/DnmAlJd86ORba8UNSOCxb1xi5g44MmIXwiJzVyU9lRuArVE9Bnpvg4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711319719; c=relaxed/simple; bh=85vqVoxtI42H/ALYmgrcO3An3l6bGc3itYafrMJW/oc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gY7e4rA7gdkGtyqnarZGQEdjqUAhJ7EkGdyTg9K7MDpRZEVDgW3qH81nvopTqMwXYFlwredMAiEoF+yFv76dz23aXeeIX3T7L/NdQgc2MmFXTsTSuVyR1iYhuXNGFOaVkBh30ojrtfi0EnZ+1AWXCdGSeaEf5WbML5EEtl0tUbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jnIq1OuU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jnIq1OuU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09BD2C43394; Sun, 24 Mar 2024 22:35:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711319718; bh=85vqVoxtI42H/ALYmgrcO3An3l6bGc3itYafrMJW/oc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jnIq1OuUe26o0Iz2M6CLuXP0Gb/uidr57ZSsu5XbTz2UOHyiSnN0hxGKR9x9e+mow AZi4xrqIY4xqQEr3vUovygvEtl/jVrbApiVdSRl49LY5sNXwiUooWb2iZhOjfsMA9O 0j3JzHPcz6vGRvbIYgCWEyt7YKdkBIysxhJE2OJWEqa6O79B5dLyJVpWdWwyPEj5OO 1NVIER/AP2nJOI6CD6Uk6weo/OE1qXcQl+ari4u7UZ53LKKN0XMS4MNNdtc8kkR+iI 6E3VTk+eXEf3Q/I5LE9kFQIH7yP47xCe92w4ptjixAu7OMyw8msb7CWMgPxYtieCiT w46ZQWTbFQjBw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Frederic Weisbecker , Kalesh Singh , "Paul E . McKenney" , Boqun Feng , Sasha Levin Subject: [PATCH 6.8 021/715] rcu/exp: Handle RCU expedited grace period kworker allocation failure Date: Sun, 24 Mar 2024 18:23:20 -0400 Message-ID: <20240324223455.1342824-22-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240324223455.1342824-1-sashal@kernel.org> References: <20240324223455.1342824-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Frederic Weisbecker [ Upstream commit e7539ffc9a770f36bacedcf0fbfb4bf2f244f4a5 ] Just like is done for the kworker performing nodes initialization, gracefully handle the possible allocation failure of the RCU expedited grace period main kworker. While at it perform a rename of the related checking functions to better reflect the expedited specifics. Reviewed-by: Kalesh Singh Fixes: 9621fbee44df ("rcu: Move expedited grace period (GP) work to RT kthread_worker") Signed-off-by: Frederic Weisbecker Reviewed-by: Paul E. McKenney Signed-off-by: Boqun Feng Signed-off-by: Sasha Levin --- kernel/rcu/tree.c | 2 ++ kernel/rcu/tree_exp.h | 25 +++++++++++++++++++------ 2 files changed, 21 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 38c86f2c040b5..f2c10d351b597 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4743,6 +4743,7 @@ static void __init rcu_start_exp_gp_kworkers(void) rcu_exp_gp_kworker = kthread_create_worker(0, gp_kworker_name); if (IS_ERR_OR_NULL(rcu_exp_gp_kworker)) { pr_err("Failed to create %s!\n", gp_kworker_name); + rcu_exp_gp_kworker = NULL; return; } @@ -4751,6 +4752,7 @@ static void __init rcu_start_exp_gp_kworkers(void) pr_err("Failed to create %s!\n", par_gp_kworker_name); rcu_exp_par_gp_kworker = NULL; kthread_destroy_worker(rcu_exp_gp_kworker); + rcu_exp_gp_kworker = NULL; return; } diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 2ac440bc7e10b..8107f818455da 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -428,7 +428,12 @@ static void sync_rcu_exp_select_node_cpus(struct kthread_work *wp) __sync_rcu_exp_select_node_cpus(rewp); } -static inline bool rcu_gp_par_worker_started(void) +static inline bool rcu_exp_worker_started(void) +{ + return !!READ_ONCE(rcu_exp_gp_kworker); +} + +static inline bool rcu_exp_par_worker_started(void) { return !!READ_ONCE(rcu_exp_par_gp_kworker); } @@ -478,7 +483,12 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp) __sync_rcu_exp_select_node_cpus(rewp); } -static inline bool rcu_gp_par_worker_started(void) +static inline bool rcu_exp_worker_started(void) +{ + return !!READ_ONCE(rcu_gp_wq); +} + +static inline bool rcu_exp_par_worker_started(void) { return !!READ_ONCE(rcu_par_gp_wq); } @@ -541,7 +551,7 @@ static void sync_rcu_exp_select_cpus(void) rnp->exp_need_flush = false; if (!READ_ONCE(rnp->expmask)) continue; /* Avoid early boot non-existent wq. */ - if (!rcu_gp_par_worker_started() || + if (!rcu_exp_par_worker_started() || rcu_scheduler_active != RCU_SCHEDULER_RUNNING || rcu_is_last_leaf_node(rnp)) { /* No worker started yet or last leaf, do direct call. */ @@ -956,7 +966,7 @@ static void rcu_exp_print_detail_task_stall_rnp(struct rcu_node *rnp) */ void synchronize_rcu_expedited(void) { - bool boottime = (rcu_scheduler_active == RCU_SCHEDULER_INIT); + bool use_worker; unsigned long flags; struct rcu_exp_work rew; struct rcu_node *rnp; @@ -967,6 +977,9 @@ void synchronize_rcu_expedited(void) lock_is_held(&rcu_sched_lock_map), "Illegal synchronize_rcu_expedited() in RCU read-side critical section"); + use_worker = (rcu_scheduler_active != RCU_SCHEDULER_INIT) && + rcu_exp_worker_started(); + /* Is the state is such that the call is a grace period? */ if (rcu_blocking_is_gp()) { // Note well that this code runs with !PREEMPT && !SMP. @@ -996,7 +1009,7 @@ void synchronize_rcu_expedited(void) return; /* Someone else did our work for us. */ /* Ensure that load happens before action based on it. */ - if (unlikely(boottime)) { + if (unlikely(!use_worker)) { /* Direct call during scheduler init and early_initcalls(). */ rcu_exp_sel_wait_wake(s); } else { @@ -1014,7 +1027,7 @@ void synchronize_rcu_expedited(void) /* Let the next expedited grace period start. */ mutex_unlock(&rcu_state.exp_mutex); - if (likely(!boottime)) + if (likely(use_worker)) synchronize_rcu_expedited_destroy_work(&rew); } EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); -- 2.43.0