From mboxrd@z Thu Jan 1 00:00:00 1970 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 48B5D1E25F9 for ; Wed, 27 Aug 2025 01:55:29 +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=1756259730; cv=none; b=gHXLrCUxxPYqhgkEckHEP/DeK5LVLckprK+Dh+/VyfAkbF4VPhebJ2pIHJjNqnpu8NITJ3xcAtQ/e0CSG6t0LuLLn/qHMnnDvb2N1p8L+2qTX5VAO54H5DId55qILlaKjcqEEmn4XPizUnola1QLeDWGgLp5JxU6zC9w5IBbLqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756259730; c=relaxed/simple; bh=EG/uyqg10U+IFfisvso0bEBlysgxBsgMwVPEVZCea5c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HCwBvwyU1JnClGN5faLP5uxw0QNLiAiYyxvLng4p8GcN0m/0xVZMR51QTIqb+ZiwHVDblgEF611f58aEg9UfKF0jmvedmB3z71pKQhYj6PFouAGyE1d61nm2HXSVZUobkXM+cz3RtFe0YTG3u4VoF/qVMN8hwkyfjb8ODTF0vDM= 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=ETjfHBI8; 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="ETjfHBI8" Received: from pps.filterd (m0279863.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 57QG72MO018862 for ; Wed, 27 Aug 2025 01:55:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= wyZ5iLGjMEfr8zWA8TqBNrggJ/o46idkE8iV1Fg6GHU=; b=ETjfHBI8Qn8OTsO+ LquT8vZTyxHCAsBfmtP94C9F/AqUCa05eBfEf3bXw2cuz5pCbYF3u/FfQ/yKzzEM eGRRPlEZLmwx0urzVzGaZGuWwiCPUmzhwT2lvc2fCqy0YJvQEkiALgJBw2bkbE1J wCB14okLSEbLNgEc7frsGu4wgEsKKcjoFJ9w0Irb8/TBZKt68mPkTuA/KghCTw+j OyIINNc2/gFbNiOb5/rsGBc2qQ4RhQlPgHoJP8+n1wZYv6tvlQANCeW4IfMVgEtf aVmPs/eplCykldzk7tjAQYPqqjPQ1jrnebTK+MTPG6gtHed/VI6AtvYYbEvOR4bi rac9+w== Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 48q5xpu5a9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 27 Aug 2025 01:55:28 +0000 (GMT) Received: by mail-pl1-f200.google.com with SMTP id d9443c01a7336-24896af06a9so5530175ad.3 for ; Tue, 26 Aug 2025 18:55:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756259728; x=1756864528; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=wyZ5iLGjMEfr8zWA8TqBNrggJ/o46idkE8iV1Fg6GHU=; b=we3l66vN78RN1xK0aPP1hrWgynFQofvM3u4zoJF3PDMtALyjraBmNPq8D2zXsxHM/Q HZ/3yoL3cIry0v6NevBS0nGPzCOkOyxS+nQjtNeCgDuxOyjg7NVnYHu9WfH8gRoSglf2 oH4SnG12LYuO2WE1xEdK5tYfEdR8I3xo25/YgQn1iUrGtWQnfVUjfNnQQ6lxj6fL/geF ifrJOi4NJE9JXwJPa4HNCZRDvQfiNKP4UoGJ9WU04y41ZqBmPAvksIE2zpt4pdqK4+lD xZQG80Jz5ayaQuisLXlwxPJBOUrDf9x7P+8cpEYTB+bIgILuOOarVlmFH+6A4YSVN5jc buKw== X-Forwarded-Encrypted: i=1; AJvYcCVFofaQkFhnrcVM64WCCodm5yw58V/5FtM78TMDmOK3trxr83/8VmLoPM1wu8vfjoOB/JeNRrl4C9vat34=@vger.kernel.org X-Gm-Message-State: AOJu0YzkRcNwGMo5bu7olfhCV8YYWsfF1pUtouEmFlyv/2qVA2tot9ft OoS72qGbi1rUIBxACmV++OPXNIpcfoy5wI537k+ibNmspVtr8bZw7Vc5ZLiQN/xp1qOrBYGFOK+ 9cu2qsavLipMzX7GB5xx+G9Zk+NTqkMdVM6XL1jMU/JlC7lM1d3QgwBqjWqnNir5GuH0= X-Gm-Gg: ASbGncuuorQjo24doXkqP7mHI8RPqZRdN3EeI/8szbtw5nSYxu48gpU8Db4bj6YQFkr OZr8NO7TR/i8CH8e7scKeDYku6DwmaSzEPwUMbB+1miSi8gx/eRO506ajZ5IX/yN2hIWptLnphB zjZp5gZu1BKbzZ7gD0DcG/nSpwKnoVuRgztBT912GB9d3QU27SnplUg4gaS5Z+Z69txrOpt27r5 Yh9yVXCTZv7P/vMw0wtZ//dwNpuOvpl/xDPMphRjYbAm4I29uKGew87whkByNGf+4YKSAfrSQy3 b/lsSL2xzBva0E6U6xtT5mo60wrpc4jGaSH+IzxdbajNJ/vfLSxJylF2I3+Pgn/2Prk+8veqhpV C1uHjTR8TgG/PiLoCXVEpEMf2KFiaYf7CY8hqgw== X-Received: by 2002:a17:903:2f44:b0:240:a222:2312 with SMTP id d9443c01a7336-2462eeeca94mr229747285ad.44.1756259727682; Tue, 26 Aug 2025 18:55:27 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH2i5XtdpRUbO/urKMakMgXLRO2eBfmK/dMCP7CKXewUgYFm/OlcVeTpLpdrPdXjPdZowBzJw== X-Received: by 2002:a17:903:2f44:b0:240:a222:2312 with SMTP id d9443c01a7336-2462eeeca94mr229747085ad.44.1756259727126; Tue, 26 Aug 2025 18:55:27 -0700 (PDT) Received: from [10.133.33.184] (tpe-colo-wan-fw-bordernet.qualcomm.com. [103.229.16.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-246687b521bsm108143455ad.60.2025.08.26.18.55.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Aug 2025 18:55:26 -0700 (PDT) Message-ID: Date: Wed, 27 Aug 2025 09:55:20 +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: is dma_mapping_error() check necessary for dma_alloc_noncoherent()? To: Marek Szyprowski , Baochen Qiang , Robin Murphy , Jeff Johnson Cc: iommu@lists.linux.dev, "linux-kernel@vger.kernel.org >> linux-kernel" , "ath11k@lists.infradead.org" References: <89954593-8236-464e-8848-e7cdcf639c0a@samsung.com> Content-Language: en-US From: Baochen Qiang In-Reply-To: <89954593-8236-464e-8848-e7cdcf639c0a@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=KOlaDEFo c=1 sm=1 tr=0 ts=68ae6590 cx=c_pps a=IZJwPbhc+fLeJZngyXXI0A==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=v1NiFcvVahR_jOWWQrIA:9 a=QEXdDO2ut3YA:10 a=uG9DUKGECoFWVXl0Dc02:22 X-Proofpoint-GUID: OJGP6yCd7DRsPUlKHgLwgXOQmNucdcaz X-Proofpoint-ORIG-GUID: OJGP6yCd7DRsPUlKHgLwgXOQmNucdcaz X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAzMyBTYWx0ZWRfX4s7+FEXoamf5 1YPD1mPEoJvPf9GhNEl73uKNMVzcS3s52XnACYlPtVKr97ErWropCoP0exEc/vps8b5+oHst5dm WqvZ3xFtoAWWIeZ8qt6UPOm+MQEDIJnr0eLLH3apng872/VgdX8WLTMrrgKibrcvpVtXEjoNwmZ 6OlmYLp+o7/t+MX65A4DwVU6Lgw94c6nBrxIqfZRs24qmSNls07ElwSNJ7BfnN1XZgoCeYu1GSP mQidlgcDeQpipvttAkwXTqO3XZD8H3HZCyF4aFTey+hkw6uEnGqc7eH9wTA8p3jzyeVTDUEHSrT sXuAez+UV2mzlN4UFiCs5ABPw/uRhBV2ebytDxdl1LsISWv4wrwcCJiqrXmnhZ2YjtbvUu9AjzS UoSCnbp6 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-26_02,2025-08-26_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 bulkscore=0 adultscore=0 phishscore=0 impostorscore=0 spamscore=0 suspectscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508230033 On 8/26/2025 10:09 PM, Marek Szyprowski wrote: > On 26.08.2025 11:44, Baochen Qiang wrote: >> Hi guys, >> >> I have a driver which allocate noncoherent DMA buffer and get the returned CPU addr tested: >> >> vaddr_unaligned = dma_alloc_noncoherent(ab->dev, rx_tid->unaligned_size, &paddr, >> DMA_BIDIRECTIONAL, GFP_ATOMIC); >> if (!vaddr_unaligned) { >> spin_unlock_bh(&ab->base_lock); >> return -ENOMEM; >> } >> >> while free the buffer >> >> dma_free_noncoherent(ab->dev, rx_tid->unaligned_size, >> rx_tid->vaddr_unaligned, >> rx_tid->paddr_unaligned, DMA_BIDIRECTIONAL); >> >> I get below warnings: >> >> DMA-API: ath11k_pci 0000:03:00.0: device driver failed to check map error[device >> address=0x00000000f3ad7000] [size=639 bytes] [mapped as single] >> WARNING: CPU: 15 PID: 64303 at kernel/dma/debug.c:1036 check_unmap+0x7e2/0x950 >> RIP: 0010:check_unmap+0x7e2/0x950 >> Call Trace: >> >> ? free_to_partial_list+0x9d/0x350 >> debug_dma_unmap_page+0xac/0xc0 >> ? debug_smp_processor_id+0x17/0x20 >> ? rcu_is_watching+0x13/0x70 >> dma_free_pages+0x56/0x180 >> [...] >> >> ---[ end trace 0000000000000000 ]--- >> DMA-API: Mapped at: >> debug_dma_map_page+0x7c/0x140 >> dma_alloc_pages+0x74/0x220 >> [...] >> >> Checking code gives me the impression that I should do dma_mapping_error() check as well. >> And indeed with below diff the warning is gone: >> >> + dma_mapping_error(ab->dev, paddr); >> >> However this does not make sense to me since IMO testing the CPU address is good enough, I >> can not imagine a valid case where DMA alloc/map fails while returning a valid CPU >> address, no? >> >> If I was right, should we remove invocation to debug_dma_map_page() in dma_alloc_pages()? > > Simply replace "if (!vaddr_unaligned)" with "if > dma_mapping_error(ab->dev, paddr)" and the debug code will be happy. Thanks, much better! But I am wondering if the debug code is worrying too much? isn't the CPU addr test already good enough? > > Best regards