From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 8F272255F52 for ; Mon, 12 Oct 2026 04:36:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791779761; cv=none; b=Nob/OjK/fEs5ZQ3TYBvq/93TPXv2FaQQzJRPEUTHeAewG9DxX6U+KD9AWmdx3rU00l7ozb9fd4eBNwePNgc4KPMXc1reKbyKyBnv9qpCnw+AnTkwbUPbq3OoFqAc5K2Q+G9UYG2UxkRTEst6XjnENMhKGV7vbNGonZE0P827KfI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791779761; c=relaxed/simple; bh=rbYdn9GSSo7LCLaVhy9r6E/05l3J2/bCyjtdv9JRI7o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=I7hHcCCaVfg/0UC/J4bs3QnKSZJrTGwPqPvG8PMy3Hk2tsX6tl/ga171HcSKyLk2OwzHOEloW9nixD+JolpBCvh5mO1/vKEEccikl/gXuksA2ZZCmClc8lLRVt5FyNVRXhmeysk+DEOu/fK/iRuGUiI8ad/dmTTSQFCaAWpPUW8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=i6JYfh92; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="i6JYfh92" Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 69C2EcCh2912982; Mon, 12 Oct 2026 04:35:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=9eYTkG l5oo0Kdw3qwx5Z794rZLTMiDY6xjAz4qWiuoM=; b=i6JYfh92WQMOwy73PsLb2/ DuLBqQuGmFqpWq3vFBLMBp/Zs5y4SXiz6GL/N3xZ97WhUuXbJ3hiMX5DwU66UNxU CHrRu46q8ZGC30Bd/9Slbpjq1NRfCg9p3YdOue8GSLukkrqpgM/39Eus8NxSei/P R3rVVuGF0nSIl6bhNvzvrYYgVsCj3cAoS0d01gX81+yGSJmMXPv9QQu6sNat7FpZ ptboZUO1rn6Xa/DLcTNC6VAtqmSGhWsc3q1goKwZ7NupVVr6wDFTGQFN/tNEgF+s 6vz3B2E/QDc58BBs5sbikQCAyDec0NZxLAIMgfSGrdGwqDFKBxVWbACpNAMg5yTg == Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4h7dwhpvq4-1 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 12 Oct 2026 04:35:35 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.11/8.18.1.11) with ESMTP id 69C24o3K563434; Mon, 12 Oct 2026 04:35:35 GMT Received: from smtprelay05.dal12v.mail.ibm.com ([172.16.1.7]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4h802vkthv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 12 Oct 2026 04:35:34 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay05.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 69C4ZYIL33620638 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 12 Oct 2026 04:35:34 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E072858156; Mon, 12 Oct 2026 04:35:33 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C6F6758155; Mon, 12 Oct 2026 04:35:29 +0000 (GMT) Received: from [9.61.185.118] (unknown [9.61.185.118]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 12 Oct 2026 04:35:29 +0000 (GMT) Message-ID: <840fbc39-dbab-45c3-9743-8f21a8259c29@linux.ibm.com> Date: Mon, 12 Oct 2026 10:05:28 +0530 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 v5 2/2] nvme-multipath: add fail_on_ctrl_loss sysfs attribute To: Krishna Iyer , kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, hare@suse.de, saravanand@crusoe.ai, sjpark@crusoe.ai References: <20261008141407.22992-1-kiyer@crusoe.ai> <20261008141407.22992-3-kiyer@crusoe.ai> Content-Language: en-US From: Nilay Shroff In-Reply-To: <20261008141407.22992-3-kiyer@crusoe.ai> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEyMDAxNiBTYWx0ZWRfXzJvBb0I+2nqg ar29cHj4bK3YITyLWcDS0MfhXT9gnfUMcXZT6gEHRHUIMNkXmy8KL9QUmR5K/uAo5qesuiCuerF WnaJgdGB1am1kaPjpSygnNuMf7n54e+Wh5AKRVDPrJqtJY3OKEKiOj0kv0pqNn0TBwW3hNApGUz 61cLPkKaf5RhtzZwKgDzhjVcpiep+EDvZN2Hbzm6ISplDCEf/1ArXVKryTwSEJE1ujZMNcHg1Wh OWYj0n3gLPit4htMfTlMRJ708ZLZCDTL8J8W6LF3SEJZQd7ctfRPBeNTDopVg8BLtTX1+8Wqt+6 Z60H2FHGvhf5EevChhmQnp+YZx7+3nvKvT5eWGfQ7ZBChRZ/HjPAZ3gk5qDGU6ePe2NkfTvj40P 4ewxKRb4YcFrLMjTHFEOBJBWZOxBxYjP6PhVMbzWfwi9v7tf24mgEPG36ycGISauLn9ZGqI/IXI VnDL4/PBHN+V5mMZO/g== X-Proofpoint-GUID: -biNSCGHsiHKTpV0i3But0QLYWUXFc1r X-Proofpoint-ORIG-GUID: -biNSCGHsiHKTpV0i3But0QLYWUXFc1r X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEyMDAxNiBTYWx0ZWRfX0LVwG8BhXBlQ VQEx5KN+HuGt7A7f0VuGv28Gf0zSZdnv01okgmPNwveTVgOXHbuFicD6z4x0RmtdRFU+B6/M/Md RphgcX8Nim3IYg5lKke+GI2fOVYTa1Q= X-Authority-Analysis: v=2.4 cv=btHZl0ai c=1 sm=1 tr=0 ts=6acc6397 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=FMbtR3q6Wjg1j8aBuHgA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-12_01,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 phishscore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610120016 On 10/8/26 7:44 PM, Krishna Iyer wrote: > When no usable path exists, I/O on a multipath namespace is queued > until a path returns. With ctrl_loss_tmo=-1 that can be forever: > during a long fabric outage any process waiting on the I/O is stuck in > D state. We hit this on virtualization hosts, where a SIGKILLed VM > process cannot exit while draining I/O to an unreachable NVMe/TCP > target. > > Nothing can fail this I/O without tearing something down: controller > deletion takes every namespace on the controller with it. > > Add a fail_on_ctrl_loss attribute on the ns-head disk: a persistent > per-namespace policy to fail parked and newly arriving I/O instead of > queueing it when no usable path exists. It is the namespace-scoped > counterpart to the controller-scoped fast_io_fail_tmo: the trigger is > an event userspace observes (a consumer known to be gone, for us a > SIGKILLed VM the host must reap), not a duration picked up front, and > sibling namespaces behind the same controllers keep queueing and ride > out the outage. > > A CONNECTING controller stops counting as an available path, and with > no controllers left the policy overrides the delayed_removal_secs > queue-if-no-path window; the two are opposites, so fail_on_ctrl_loss > takes precedence when both are set. ANA change and controller resetting > still queue, since both are transient. Controller state is untouched and > reconnects continue. Like dm-multipath, the policy is transport > agnostic. > > Assisted-by: Claude:claude-fable-5 > Signed-off-by: Krishna Iyer Looks good to me: Reviewed-by: Nilay Shroff