From nobody Mon Feb 9 14:44:09 2026 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (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 DF3A221D3C5 for ; Tue, 30 Dec 2025 09:17:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767086235; cv=none; b=o69OhzqZwozloV+EEMiW10k3sUroa7XI/Q2SaLISmowbX2I5845vUF+BAhhtb/07EJlboRQvlW/xdZI8NJee2Lsxg0g7wrKYmpSRj/SHwO5WUEwAkSYkI/w1E3yY5RJ/EXWxjmBhFd0/HeFzYOsBQLBqXP1b4P05su69JGySpo0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767086235; c=relaxed/simple; bh=OEFP+R5W0TdmFr38wbq8rdvuZ0rIdRq2p8OrrwrGuOc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=IbQ66+sUgfrwDnTjqZgTgUQEi7XEnT1kZyCy/MLOpcFoBxLL6dEUZjBNdRpzdrkdYbf7lfCED1eDajKChlKMz4kAQ8VsDVjO1J2HCs6FtFeph5FKT55Vdrk/peXu4JIj1SOd1SUSYn1+BfQOkoHLBXAbGmgbwxlth6OC92ZCstk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=dYIdQQmm; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=J6XHg3xc; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="dYIdQQmm"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="J6XHg3xc" Received: from pps.filterd (m0279866.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 5BU3hspH2547842 for ; Tue, 30 Dec 2025 09:17:13 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=qcppdkim1; bh=Y2H9HrTByKwVMEK6NHL3zd BV54N35hz6e6E0f8xL6x8=; b=dYIdQQmmcoLWFb1sLjtzdeDIrykgslgyLkNDZn Hx295L6i/hDvKqpK147JbGJtnmidHpJwkV0whUiL8z51n911JoRvKt0fLNg44h28 JC3f+5su+uLVh55vOcKsUSUzKuO6YGu3VrT7W5qU9kXfaXXxRM+ee1rZYcsadzOM JJjdz+EcnjHH4rb4jmMdRyrlPiOM7umNY1KfgMuWBvHJywc8sqAP4OPC8Ivy/321 rQY72810RkjGQvNk9YR+juSFlAzodf7QxLGAx1j6J2OuNW03swFi/NX4RanRm2J8 vukQWAjW5AdO4zzhdU3LLqPn+/VSttFplB6iC1pG2C8yJYHw== Received: from mail-pl1-f198.google.com (mail-pl1-f198.google.com [209.85.214.198]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4bc7398q6g-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Tue, 30 Dec 2025 09:17:13 +0000 (GMT) Received: by mail-pl1-f198.google.com with SMTP id d9443c01a7336-2a0a0bad5dfso204289765ad.0 for ; Tue, 30 Dec 2025 01:17:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1767086232; x=1767691032; darn=vger.kernel.org; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=Y2H9HrTByKwVMEK6NHL3zdBV54N35hz6e6E0f8xL6x8=; b=J6XHg3xcylCxLUqqH5J8CXZQdI9hwVDOKrClxjuOMt3Fv1C9FmIT2g/e3LTTEYS/+Q mll5+/Q0Z8HG3wm9qYPz2RJu5yq9L7vANqPk/mWYa8Hi3T4H7O+9EDtfQC2cKocjrtZ9 79dIJN52rpUyHb7mTDyBAvaQuVIMrjYFZrvhyVgH4BiQSxRRlT+/PjXxacuiCgH4LE0C 2ld53Y/IVUv10Ymf4YQ4wg88otQZD84vqqAfu2V2YgOYfjYyPwVqj5p22PKFPsIKqKpb JZsxyKy21a/OElyw4+b+UCOpf+KJc0LEEYC4062wdaSxYNH/fe5mHpDNUpSHhMm692Sg aIrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767086232; x=1767691032; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Y2H9HrTByKwVMEK6NHL3zdBV54N35hz6e6E0f8xL6x8=; b=v7C6ZJQobm3oaHWvUXRbc3Wvek7lpv4Mkf6i5xgfi2eOhYnvu7lQ678DBxnNIayMA2 m/Pz30YxP9thCoMzNiinPFZ2F6hPp+5EfDeVnHL0h6YyK0qhnCaVTl0lfqFexKhnNNuu iGdR/r84bVWqa9veamuXKTrPPpFyyXHRjyBcwfIVXO/XZqg76OPDKtCs/5HURP5yC5VQ Jk4hnUkSlINrxKZdIJ6R5ZwfLpLwjxtxmpBE6+REol+GCYZP9DbjBuNnvE5oXZHeoztT TybY65VM6f25UABWZoav8SSuhfjpLn35kiuxkDRfALHCv1rJomWgIudOKI7JLp11oIyv jpcw== X-Forwarded-Encrypted: i=1; AJvYcCWA06d6pPEFpZZYf3uHE/5YWGTsBKeYLK7JTiPHTSNx1CO9M2bOEPS7z8alq3cRsnHTPrFmjZGCEqAztIY=@vger.kernel.org X-Gm-Message-State: AOJu0YwbsuMiR4q/DgegSPlom6lKFaU+iTOHB0N7064NyX6yPSGNNvmU Ii6jwofhCIiOcydaO61i3YVZxcpyt5Ld+KqvOeMBYF0wE3GFZENlUFuMEHVaSDi7gbRTWxVLitH W3efkjCN2JFoFYDwxnvivgWPzY6ea52xANVMdqqlk8lItYSit+/u0zdM4fg1Jg7hYJ5Y= X-Gm-Gg: AY/fxX5BOwK1ZTvYVrTDWELjDfzf8/+lccWoQLCWDYNIEOhViUdQg9oI20qEfCYQ18N 4SQ3Ql9Knw0dYueqrh07kAzs7sJTgkhe7DQZFE/fie+83/rwK0Aaaz5sxCOrTl3a7WEKqlHM+tQ yoe7viN6ut3QsIU3vKsnGNYtAKHtCg1D4RVsGREdaMxZekJKebyiitVlAoy5RWhghHezI1JUdO1 YzkfeemecTocMnQ4cj+amrobe1lYoEuQhIeMKsnQ7Ti+6Vqej1dY186WKSmdxKO0YaRNsNiFGa3 zWCK8qivIumwzr3U7LQ1ygHWG5XGvdCMjXai5ysuEoPE5CXWeI9cBioPwX61LQX3X+hS9bDx4PX t9tAr5WwfJZxVnuWB+8IdFpt3eX9rXoQDNQ5C6htbKaTkR2dQu1sBDS5j7KI4qhg+oj3QUjjqnU zBKp4EI4E= X-Received: by 2002:a17:902:e74c:b0:298:5fde:5a93 with SMTP id d9443c01a7336-2a2f2a354c9mr339312395ad.32.1767086232420; Tue, 30 Dec 2025 01:17:12 -0800 (PST) X-Google-Smtp-Source: AGHT+IFu0YURIBL2I5NuLZPSURk18DQXRfkY6JIrOopCNmJ9kAdUTUUIYFgMkA3tVNzOdopoingwyQ== X-Received: by 2002:a17:902:e74c:b0:298:5fde:5a93 with SMTP id d9443c01a7336-2a2f2a354c9mr339312115ad.32.1767086231852; Tue, 30 Dec 2025 01:17:11 -0800 (PST) Received: from congzhan02.ap.qualcomm.com (tpe-colo-wan-fw-bordernet.qualcomm.com. [103.229.16.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a2f3c6661esm289208185ad.2.2025.12.30.01.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Dec 2025 01:17:11 -0800 (PST) From: Cong Zhang Date: Tue, 30 Dec 2025 17:17:05 +0800 Subject: [PATCH] blk-mq: skip CPU offline notify on unmapped hctx Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251230-blk_mq_no_ctx_checking-v1-1-2168131383e6@oss.qualcomm.com> X-B4-Tracking: v=1; b=H4sIAJCYU2kC/x3MQQqAIBBA0avErBNUMKqrREjaVIOlpRFBdPek5 Vv8/0DCSJigLR6IeFGi4DNEWYBdBj8jozEbJJdKSFkxszq9HdoHbc9b2wWtIz8zrkxVT8rUphk hx3vEie5/3PXv+wHGx2XWaAAAAA== X-Change-ID: 20251226-blk_mq_no_ctx_checking-05b68f5b8b9d To: Jens Axboe Cc: linux-arm-msm@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Cong Zhang X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1767086230; l=1670; i=cong.zhang@oss.qualcomm.com; s=20250926; h=from:subject:message-id; bh=OEFP+R5W0TdmFr38wbq8rdvuZ0rIdRq2p8OrrwrGuOc=; b=ttI4m9W/1jpUSabnmV7CDfIDqysMDbcEQyd1gfWm3Pe7Irj/LaC+uu7KBnnn27xVW4TUQdKPc fTB6oMnCLMRCR6ZmX0AoPW63DNW4QRRF7aw80K8IP9Poo4djahtorV5 X-Developer-Key: i=cong.zhang@oss.qualcomm.com; a=ed25519; pk=8SBh3ey5igz2nlW+UFC6khFvaNPgG7MmbWtAeO2s6n8= X-Proofpoint-GUID: 6wsmYcvyPYBR7LjBGnLjyaUsbwF6pbqp X-Authority-Analysis: v=2.4 cv=HrV72kTS c=1 sm=1 tr=0 ts=69539899 cx=c_pps a=MTSHoo12Qbhz2p7MsH1ifg==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=wP3pNCr1ah4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=X6FGcEPeVORPTCNb1acA:9 a=QEXdDO2ut3YA:10 a=GvdueXVYPmCkWapjIL-Q:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjMwMDA4MyBTYWx0ZWRfX1Xa6N56YV0oi YLq18ETokgXzrjQcjTW85XW6/ah83UB478FSeEt2tqWthh8/oODWxkg5OZyR7mjhlxH62dOhqmj cq2s5nt3DMWpM3VLq21RHqVbggyvCa4MSDPbxZxUt+32/dWvnT1bnlAVsKsVtLsYYP0CGdBAQ4S XmfQwKtcXuNvWk7VvKyJz3zrvC2uj5yVeWxgiwspnRTEveP4bEKO6qbZ2C+pDyBzsyvc/OxOvrh +VtxMg7LNmSOqLTvrAcMJSJKXq4jt05i/1liFf4ZjC7uzSfJfSyD7Fk5AZXlfj6vYMO2tBt2Krf Karadb1bUd/3Ot52QBw5duODIm7tbjbjHxmPzW63886WO++zPmQRNrebfdzvkI9yfbVk+9Lbw9n L55OuDsOX2nGLHX0XntTIuuMEwfX2hVF7Rr5lBZt3BR9s25jjiuFkWxL3c2leP9WFZr3cqYOD9q a+6XZaQS2nSMH4ZNYLw== X-Proofpoint-ORIG-GUID: 6wsmYcvyPYBR7LjBGnLjyaUsbwF6pbqp X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-29_07,2025-12-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 adultscore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 priorityscore=1501 bulkscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2512120000 definitions=main-2512300083 If an hctx has no software ctx mapped, blk_mq_map_swqueue() never allocates tags and leaves hctx->tags NULL. The CPU hotplug offline notifier can still run for that hctx, return early since hctx cannot hold any requests. Signed-off-by: Cong Zhang Reviewed-by: Ming Lei --- This issue was observed during CPU hotplug. If an hctx is not mapped, offlining a CPU can trigger a kernel crash. When a block device does not map all hctx, some hctx instances may remain unused. These unused hctx can still receive CPU offline notifications and enter blk_mq_hctx_notify_offline(). blk_mq_hctx_notify_offline() calls blk_mq_hctx_has_requests() to check whether there are pending requests on the hctx. However, unused hctx do not have tags allocated, which leads to a crash. Since an unused hctx cannot have any requests, fix this by returning early when nr_ctx is zero, skipping blk_mq_hctx_notify_offline(). --- block/blk-mq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 1978eef95dca3fb332a73aeff7b9613ee770a8a3..eff4f72ce83be80aac9da86aab3= 5079be7d2b5e4 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3721,7 +3721,7 @@ static int blk_mq_hctx_notify_offline(unsigned int cp= u, struct hlist_node *node) struct blk_mq_hw_ctx, cpuhp_online); int ret =3D 0; =20 - if (blk_mq_hctx_has_online_cpu(hctx, cpu)) + if (!hctx->nr_ctx || blk_mq_hctx_has_online_cpu(hctx, cpu)) return 0; =20 /* --- base-commit: cc3aa43b44bdb43dfbac0fcb51c56594a11338a8 change-id: 20251226-blk_mq_no_ctx_checking-05b68f5b8b9d Best regards, --=20 Cong Zhang