From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 013.lax.mailroute.net (013.lax.mailroute.net [199.89.1.16]) (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 6B7D61624C5; Tue, 6 Jan 2026 12:29:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767702590; cv=none; b=AV5fEhyjOUcwdsOzKKrSTXYQtyuYOjtCvjSeNJbmtowbMnwhEekBbaPVEBEyywBgHexMTGJFWfQyQbO0tGilyUtfeTQGG0aizVbyRG929xgC/nNM6j3V9G5HvuKYUGxK9suzyHezjggHQqnmFsJEORKcp7CC4fylexbzBm9LQkc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767702590; c=relaxed/simple; bh=w8ErrOQEKlfLGXbK2LIOSRpPj12EsGD6jcYl2D59xs0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DILrGnPgHhheX6FGBuNv1mZRi6R5gWXuSSR4zRDV7M3I8E9PcbiRciYkr7/OMaWaFSMm4rntWy5y03URQ6gKaRPDUDPi/l+9dmhkQ10Sc566KMeGXCx3kTN5NCOYqbLJDbiLEAb0RwHON1Zbh+RaxWzU4sRQcRrRUWoiL8aBNwU= 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=YjeXsS+z; arc=none smtp.client-ip=199.89.1.16 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="YjeXsS+z" Received: from localhost (localhost [127.0.0.1]) by 013.lax.mailroute.net (Postfix) with ESMTP id 4dlr8Q2XVvzlvgjk; Tue, 6 Jan 2026 12:29:42 +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=1767702580; x=1770294581; bh=7jHnsEAoTkixr6ViC3i/D2kr OYaTAc7gfumuPM9qGO0=; b=YjeXsS+zGsoMKytfaXuTSv129Gm8NkuvlFXu8diK QBzKwC9ydoGZf+OVWiCmKGGkvs5pUxvuImgQ4/NPvgVS4LQ6kbjTogifSIEnqDrd wujEZ7HSBKiKfPgt+Fg4cbGr9HiueW6Ozq9rn6ivsfalJd59DiPR7okYidnW22ez pVQVl2B/7sB7z315x+JSOKHVF0W7YVjO1tvfLsnS8HZa0eN3FE037anMBbFj4aCV Me0qwlR2viwEbQKbJ10jJYPMS97es68a/7AQxqJdNtYHnr157PsCiXSeu6XTIbSF xIZiwsjsZMZh+2j0A/9iKkgE/fr2QXhenCH6RI/8Ucy9Hw== X-Virus-Scanned: by MailRoute Received: from 013.lax.mailroute.net ([127.0.0.1]) by localhost (013.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id uGgBFtkSTfm0; Tue, 6 Jan 2026 12:29:40 +0000 (UTC) Received: from [192.168.50.14] (c-73-231-117-72.hsd1.ca.comcast.net [73.231.117.72]) (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 013.lax.mailroute.net (Postfix) with ESMTPSA id 4dlr8K1gh6zlfgf6; Tue, 6 Jan 2026 12:29:36 +0000 (UTC) Message-ID: <6eb6abcf-26aa-473d-843e-428ae0f38203@acm.org> Date: Tue, 6 Jan 2026 04:29:36 -0800 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 v2 2/2] block: Fix WARN_ON in blk_mq_run_hw_queue when called from interrupt context To: djiony2011@gmail.com, ming.lei@redhat.com Cc: axboe@kernel.dk, gregkh@linuxfoundation.org, ionut.nechita@windriver.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, muchun.song@linux.dev, sashal@kernel.org, stable@vger.kernel.org References: <20260106111411.6435-1-ionut.nechita@windriver.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: <20260106111411.6435-1-ionut.nechita@windriver.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/6/26 3:14 AM, djiony2011@gmail.com wrote: > [Mon Dec 22 10:18:18 2025] WARNING: CPU: 190 PID: 2041 at block/blk-mq.c:2291 blk_mq_run_hw_queue+0x1fa/0x260 > [Mon Dec 22 10:18:18 2025] Modules linked in: > [Mon Dec 22 10:18:18 2025] CPU: 190 PID: 2041 Comm: kworker/u385:1 Tainted: G W 6.6.0-1-rt-amd64 #1 Debian 6.6.71-1 6.6.71 is pretty far away from Jens' for-next branch. Please use Jens' for-next branch for testing kernel patches intended for the upstream kernel. > [Mon Dec 22 10:18:18 2025] Call Trace: > [Mon Dec 22 10:18:18 2025] > [Mon Dec 22 10:18:18 2025] blk_mq_run_hw_queues+0x6c/0x130 > [Mon Dec 22 10:18:18 2025] blk_queue_start_drain+0x12/0x40 > [Mon Dec 22 10:18:18 2025] blk_mq_destroy_queue+0x37/0x70 > [Mon Dec 22 10:18:18 2025] __scsi_remove_device+0x6a/0x180 > [Mon Dec 22 10:18:18 2025] scsi_alloc_sdev+0x357/0x360 > [Mon Dec 22 10:18:18 2025] scsi_probe_and_add_lun+0x8ac/0xc00 > [Mon Dec 22 10:18:18 2025] __scsi_scan_target+0xf0/0x520 > [Mon Dec 22 10:18:18 2025] scsi_scan_channel+0x57/0x90 > [Mon Dec 22 10:18:18 2025] scsi_scan_host_selected+0xd4/0x110 > [Mon Dec 22 10:18:18 2025] do_scan_async+0x1c/0x190 > [Mon Dec 22 10:18:18 2025] async_run_entry_fn+0x2f/0x130 > [Mon Dec 22 10:18:18 2025] process_one_work+0x175/0x370 > [Mon Dec 22 10:18:18 2025] worker_thread+0x280/0x390 > [Mon Dec 22 10:18:18 2025] kthread+0xdd/0x110 > [Mon Dec 22 10:18:18 2025] ret_from_fork+0x31/0x50 > [Mon Dec 22 10:18:18 2025] ret_from_fork_asm+0x1b/0x30 Where in the above call stack is the code that disables interrupts? > 3. **The actual problem on PREEMPT_RT**: There's a preceding "scheduling while atomic" > error that provides the real context: > > [Mon Dec 22 10:18:18 2025] BUG: scheduling while atomic: kworker/u385:1/2041/0x00000002 > [Mon Dec 22 10:18:18 2025] Call Trace: > [Mon Dec 22 10:18:18 2025] dump_stack_lvl+0x37/0x50 > [Mon Dec 22 10:18:18 2025] __schedule_bug+0x52/0x60 > [Mon Dec 22 10:18:18 2025] __schedule+0x87d/0xb10 > [Mon Dec 22 10:18:18 2025] rt_mutex_schedule+0x21/0x40 > [Mon Dec 22 10:18:18 2025] rt_mutex_slowlock_block.constprop.0+0x33/0x170 > [Mon Dec 22 10:18:18 2025] __rt_mutex_slowlock_locked.constprop.0+0xc4/0x1e0 > [Mon Dec 22 10:18:18 2025] mutex_lock+0x44/0x60 > [Mon Dec 22 10:18:18 2025] __cpuhp_state_add_instance_cpuslocked+0x41/0x110 > [Mon Dec 22 10:18:18 2025] __cpuhp_state_add_instance+0x48/0xd0 > [Mon Dec 22 10:18:18 2025] blk_mq_realloc_hw_ctxs+0x405/0x420 > [Mon Dec 22 10:18:18 2025] blk_mq_init_allocated_queue+0x10a/0x480 How is the above call stack related to the reported problem? The above call stack is about request queue allocation while the reported problem happens during request queue destruction. > I apologize for the confusion in my commit message. Should I: > 1. Revise the commit message to accurately describe the blk_queue_start_drain() path? > 2. Add details about the PREEMPT_RT context causing the atomic state? The answer to both questions is yes. Thanks, Bart.