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 A1499246B3C; Wed, 11 Dec 2024 18:51:59 +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=1733943119; cv=none; b=abXGzsoN1G6dI0rLyLu0T7iolEAaGMC/h1VCFmIfVG6uJyOCAWKLDLov9LUKjbaCAdcNlqy1fHk3Pa4iw/WhN6fe0B9r3EeaAgn56UzarLItNcTmcEYBaOzYGnn/QJ9OTFtGepxs1uqdPkJGrTXY4WGsAS/9GDU3n+IDsMxOKaA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733943119; c=relaxed/simple; bh=0ApqLa5ohk2HCuhaPK/iP86UCfKeLgHYSZtpGd/yALg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u6VLRLQ6l9xKFa3gau7ej1U5RM7aNy2aaZ6cCyzjtqAv/RCuGQqZf8KjsmsXFQQNWGt9QMV4TQBARnPwbeRTI7OxAspEGi1vBnteqy1yVsdgh/mq8xVZNWxyNU/2g3vLEipjbldBe34CsnYlEKjWj07tAM16Rx6kBbnnXmkVJjQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fOpaReZU; 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="fOpaReZU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 367CDC4CED2; Wed, 11 Dec 2024 18:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733943119; bh=0ApqLa5ohk2HCuhaPK/iP86UCfKeLgHYSZtpGd/yALg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fOpaReZUKhy+fuXAy+2RsPvfXZE6U3+8nqjBozNG560ApGWbQmmIi6Gts6UfKcdAa VaqTUMZYE0xV13A3Kf4nJAuS9HR07iTlnqo9eIBGB56uxurmSNTVgHZEOqWbWdqJfy 885snMzhfa72aFjp52drRlPg4qLPJibHZBStHt/qvhPW73JG2BseUswGALalaojzG1 2MoxlRXvqzMCnutZlESgp1KBxY45+QZ0PU46XGa0Rn0Gk+PowEXepUBTIu+JuAq/fU koDFz+HKLlQe4cf0hkYuRLtHu1c56HgHHNn26vFOR7UbKSwqmhtG7EIAsQaW9Jseks 69ZE3Mb8ML2Ow== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ming Lei , Reinette Chatre , Fenghua Yu , Peter Newman , Babu Moger , Luck Tony , Jens Axboe , Sasha Levin , linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 36/36] blk-mq: move cpuhp callback registering out of q->sysfs_lock Date: Wed, 11 Dec 2024 13:49:52 -0500 Message-ID: <20241211185028.3841047-36-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241211185028.3841047-1-sashal@kernel.org> References: <20241211185028.3841047-1-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 X-stable-base: Linux 6.12.4 Content-Transfer-Encoding: 8bit From: Ming Lei [ Upstream commit 22465bbac53c821319089016f268a2437de9b00a ] Registering and unregistering cpuhp callback requires global cpu hotplug lock, which is used everywhere. Meantime q->sysfs_lock is used in block layer almost everywhere. It is easy to trigger lockdep warning[1] by connecting the two locks. Fix the warning by moving blk-mq's cpuhp callback registering out of q->sysfs_lock. Add one dedicated global lock for covering registering & unregistering hctx's cpuhp, and it is safe to do so because hctx is guaranteed to be live if our request_queue is live. [1] https://lore.kernel.org/lkml/Z04pz3AlvI4o0Mr8@agluck-desk3/ Cc: Reinette Chatre Cc: Fenghua Yu Cc: Peter Newman Cc: Babu Moger Reported-by: Luck Tony Signed-off-by: Ming Lei Tested-by: Tony Luck Link: https://lore.kernel.org/r/20241206111611.978870-3-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-mq.c | 103 +++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 92 insertions(+), 11 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index c4012cb3adbf1..6dd849d607c03 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -43,6 +43,7 @@ static DEFINE_PER_CPU(struct llist_head, blk_cpu_done); static DEFINE_PER_CPU(call_single_data_t, blk_cpu_csd); +static DEFINE_MUTEX(blk_mq_cpuhp_lock); static void blk_mq_insert_request(struct request *rq, blk_insert_t flags); static void blk_mq_request_bypass_insert(struct request *rq, @@ -3740,13 +3741,91 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) return 0; } -static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx) +static void __blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx) { - if (!(hctx->flags & BLK_MQ_F_STACKING)) + lockdep_assert_held(&blk_mq_cpuhp_lock); + + if (!(hctx->flags & BLK_MQ_F_STACKING) && + !hlist_unhashed(&hctx->cpuhp_online)) { cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE, &hctx->cpuhp_online); - cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD, - &hctx->cpuhp_dead); + INIT_HLIST_NODE(&hctx->cpuhp_online); + } + + if (!hlist_unhashed(&hctx->cpuhp_dead)) { + cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD, + &hctx->cpuhp_dead); + INIT_HLIST_NODE(&hctx->cpuhp_dead); + } +} + +static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx) +{ + mutex_lock(&blk_mq_cpuhp_lock); + __blk_mq_remove_cpuhp(hctx); + mutex_unlock(&blk_mq_cpuhp_lock); +} + +static void __blk_mq_add_cpuhp(struct blk_mq_hw_ctx *hctx) +{ + lockdep_assert_held(&blk_mq_cpuhp_lock); + + if (!(hctx->flags & BLK_MQ_F_STACKING) && + hlist_unhashed(&hctx->cpuhp_online)) + cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE, + &hctx->cpuhp_online); + + if (hlist_unhashed(&hctx->cpuhp_dead)) + cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, + &hctx->cpuhp_dead); +} + +static void __blk_mq_remove_cpuhp_list(struct list_head *head) +{ + struct blk_mq_hw_ctx *hctx; + + lockdep_assert_held(&blk_mq_cpuhp_lock); + + list_for_each_entry(hctx, head, hctx_list) + __blk_mq_remove_cpuhp(hctx); +} + +/* + * Unregister cpuhp callbacks from exited hw queues + * + * Safe to call if this `request_queue` is live + */ +static void blk_mq_remove_hw_queues_cpuhp(struct request_queue *q) +{ + LIST_HEAD(hctx_list); + + spin_lock(&q->unused_hctx_lock); + list_splice_init(&q->unused_hctx_list, &hctx_list); + spin_unlock(&q->unused_hctx_lock); + + mutex_lock(&blk_mq_cpuhp_lock); + __blk_mq_remove_cpuhp_list(&hctx_list); + mutex_unlock(&blk_mq_cpuhp_lock); + + spin_lock(&q->unused_hctx_lock); + list_splice(&hctx_list, &q->unused_hctx_list); + spin_unlock(&q->unused_hctx_lock); +} + +/* + * Register cpuhp callbacks from all hw queues + * + * Safe to call if this `request_queue` is live + */ +static void blk_mq_add_hw_queues_cpuhp(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned long i; + + mutex_lock(&blk_mq_cpuhp_lock); + queue_for_each_hw_ctx(q, hctx, i) + __blk_mq_add_cpuhp(hctx); + mutex_unlock(&blk_mq_cpuhp_lock); } /* @@ -3797,8 +3876,6 @@ static void blk_mq_exit_hctx(struct request_queue *q, if (set->ops->exit_hctx) set->ops->exit_hctx(hctx, hctx_idx); - blk_mq_remove_cpuhp(hctx); - xa_erase(&q->hctx_table, hctx_idx); spin_lock(&q->unused_hctx_lock); @@ -3815,6 +3892,7 @@ static void blk_mq_exit_hw_queues(struct request_queue *q, queue_for_each_hw_ctx(q, hctx, i) { if (i == nr_queue) break; + blk_mq_remove_cpuhp(hctx); blk_mq_exit_hctx(q, set, hctx, i); } } @@ -3838,11 +3916,6 @@ static int blk_mq_init_hctx(struct request_queue *q, if (xa_insert(&q->hctx_table, hctx_idx, hctx, GFP_KERNEL)) goto exit_flush_rq; - if (!(hctx->flags & BLK_MQ_F_STACKING)) - cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE, - &hctx->cpuhp_online); - cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead); - return 0; exit_flush_rq: @@ -3877,6 +3950,8 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set, INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn); spin_lock_init(&hctx->lock); INIT_LIST_HEAD(&hctx->dispatch); + INIT_HLIST_NODE(&hctx->cpuhp_dead); + INIT_HLIST_NODE(&hctx->cpuhp_online); hctx->queue = q; hctx->flags = set->flags & ~BLK_MQ_F_TAG_QUEUE_SHARED; @@ -4415,6 +4490,12 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, xa_for_each_start(&q->hctx_table, j, hctx, j) blk_mq_exit_hctx(q, set, hctx, j); mutex_unlock(&q->sysfs_lock); + + /* unregister cpuhp callbacks for exited hctxs */ + blk_mq_remove_hw_queues_cpuhp(q); + + /* register cpuhp for new initialized hctxs */ + blk_mq_add_hw_queues_cpuhp(q); } int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, -- 2.43.0