From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 011.lax.mailroute.net (011.lax.mailroute.net [199.89.1.14]) (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 431E1345EDF; Wed, 22 Jul 2026 17:44:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784742275; cv=none; b=FyT9oE5IjstXTizek8yQI7rDkoQM3vKpmDXYpePQheGOfdclvyUYMatwItnyNroA9Hc9PmcC4lmfQ+trhDcPSI08ZLgqGPtsuoeKBdaz0BkbBIEHqZB5L8uZUv+R0swCJ+QJYvfkJ7OpWRuhfePiw51J7+BEwSECGUnXFWNnrvk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784742275; c=relaxed/simple; bh=GhXyyqCSbwdPauQCxggFmDGHyi/5SzNmjKhdTF4cp3c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=trlf4mg4u79xOl708kCrzAUVtIqI5BXd91FEci5uvHjhgf4N1YolLApTjTzHPDHEIKbPvQFCvR1bRifh8nPCnaldCEMdSOvOCtEwa345CmYU8G3S2IMLVUL71tYksqtHJb27zT014iaas0LGGjmnVokHsMCj148TxdlgDwJLkfE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=2zI2mLo/; arc=none smtp.client-ip=199.89.1.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="2zI2mLo/" Received: from localhost (localhost [127.0.0.1]) by 011.lax.mailroute.net (Postfix) with ESMTP id 4h51pn5SLqz1XM6JW; Wed, 22 Jul 2026 17:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1784742271; x=1787334272; bh=eCgBdiwHc05/Nzk4yzjAqgnd zMUH/E/riEl947dL7rk=; b=2zI2mLo/pKIhSFbBhCStTKEQwkNtwz8q7ZNIcCmo BIIkIBTQSGxyFR5IGqIARfjz+66RnvPCsYikG+F/HhN92iBzWIuajN4vxQFdxF87 y73nAI0/mg+pKMM/zGW82JBnQvp2kyPdXH9KDKm70kf+bHn71pgfcqhJZaDpUEjG XeCZyIYwDWOKlTkquCRkugE8oRZlTXbIwZkLLVrhLXpT8KgMDw4V7MtoNH4tg4Bb W/8UerAZ6DQX/JIhq9uTuYf8vcgnenxhgjo9+9SnskAnbbpXgR8jWYYyn8gzd0He ImQX1K842qGXMrdaDIYbbWCiYDkSb63+G8dBPhcvmxCL+Q== X-Virus-Scanned: by MailRoute Received: from 011.lax.mailroute.net ([127.0.0.1]) by localhost (011.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id QFyTvQZbBOWt; Wed, 22 Jul 2026 17:44:31 +0000 (UTC) Received: from [100.119.48.131] (unknown [104.135.180.219]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 011.lax.mailroute.net (Postfix) with ESMTPSA id 4h51pk21sJz1XM6JT; Wed, 22 Jul 2026 17:44:29 +0000 (UTC) Message-ID: <84d487e9-8350-4427-8d38-68ff6d0bf17a@acm.org> Date: Wed, 22 Jul 2026 10:44:28 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] block/mq-deadline: hold elevator_lock in debugfs next_rq show To: Xixin Liu , linux-block@vger.kernel.org Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org References: <2e689b2c4021.1784615432.git.liuxixin@kylinos.cn> Content-Language: en-US From: Bart Van Assche In-Reply-To: <2e689b2c4021.1784615432.git.liuxixin@kylinos.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/20/26 11:30 PM, Xixin Liu wrote: > diff --git a/block/mq-deadline.c b/block/mq-deadline.c > index 824bfc17b2c6..e7c4a91b2d08 100644 > --- a/block/mq-deadline.c > +++ b/block/mq-deadline.c > @@ -842,14 +842,22 @@ static int deadline_##name##_next_rq_show(void *data, \ > struct seq_file *m) \ > { \ > struct request_queue *q = data; \ > - struct deadline_data *dd = q->elevator->elevator_data; \ > - struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ > + struct elevator_queue *e; \ > + struct deadline_data *dd; \ > + struct dd_per_prio *per_prio; \ > struct request *rq; \ > + int ret; \ > \ > + ret = mutex_lock_interruptible(&q->elevator_lock); \ > + if (ret) \ > + return ret; \ > + e = q->elevator; \ > + if (!e) \ > + goto unlock; \ > + dd = e->elevator_data; \ > + per_prio = &dd->per_prio[prio]; \ > rq = deadline_from_pos(per_prio, data_dir, \ > per_prio->latest_pos[data_dir]); \ > if (rq) \ > __blk_mq_debugfs_rq_show(m, rq); \ > +unlock: \ > + mutex_unlock(&q->elevator_lock); \ > return 0; \ > } > The above patch uses the wrong lock and brings way too much code under the lock. Please help with testing this patch: diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 6e8f87e07eb9..c52601c1fa13 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -850,6 +850,7 @@ static int deadline_##name##_next_rq_show(void *data, \ struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ struct request *rq; \ \ + guard(spinlock)(&dd->lock); \ rq = deadline_from_pos(per_prio, data_dir, \ per_prio->latest_pos[data_dir]); \ if (rq) \