From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f42.google.com (mail-qv1-f42.google.com [209.85.219.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CABB1DC73E for ; Wed, 4 Sep 2024 16:05:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725465903; cv=none; b=OE3VNd224PLMF786XAyl9JP7bCbNTOn0qvX/3kgZc7bsh35a91mX9YpfHrp5eUc74BfJw+jVGuGTNlnlzRhctz0KnjckLbUHSN/BJ9VmVZ8gUv++qOB7FajW43AcpBNKUNjXJ1SLudMBQKG5vwbg/MXIA1AeoKeBl/rf17XLvDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725465903; c=relaxed/simple; bh=DvLfTv5X8abSMYa7gU+hARytb8ZhyJi6DaoaNLUA+bM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Tcswg5+NFAD/B9dzX4mjjbRyizVdqH6MpyYrtiLLwpPQFxupM5r53Ho1dK0VxEYISsq1saFf46ff8JSDhFVWT/x1tEts5z2dbsiFa+KYHLmkDSen7bKkFwEO5djDLcvW6JUHrqTC4xxko6NM3s2cg9klNIkZCh9x5Qg+gw4PGnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=Fkr0MA3S; arc=none smtp.client-ip=209.85.219.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="Fkr0MA3S" Received: by mail-qv1-f42.google.com with SMTP id 6a1803df08f44-6c51d1df755so3077586d6.1 for ; Wed, 04 Sep 2024 09:05:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1725465900; x=1726070700; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=9YeCpUy4sVnINWC6Xk3yK4/LX4CcZsc10wOEHsII+8k=; b=Fkr0MA3SNxfj08T5z6oxJ0pUIDXR5BNYdocreBLOoMFhxmvTYNn5wVqfqhQACvrnmb jKtPb7TFbx7WfBpHv0uFXYnHD7GpfwbsOKx2DgtHx/vPLB9bvx+l1lY7fU+sYLFxKqVQ 79sQ4wwcDifdAFJGAN4udW6bhhYdHwsTrJx9mdlSFgDtjBf70gjucT2lHkkyHxfUhGYX fhdYibdmoyHYaq6gQToj50JNfvFHiCIc4de8rRjNNUXaMoETd4Kh482vVIA2slGCPsR/ m1iqKmXlUSRstdWasRiIUV6YFyjd34BnR1bcvcMVsNRZGiD1jGja33qoh7PNAFOVQg0/ CZog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725465900; x=1726070700; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=9YeCpUy4sVnINWC6Xk3yK4/LX4CcZsc10wOEHsII+8k=; b=ioIVZJXWWEoHOnYWetMdVg79sM3W2+EpsDQJoJkFQzYUKm0EmzkpCac5m515oqV6NG U7EtC6RndiC5s8CxYWJSaSUqhSkTRHBe5u4AWLUWDbZNfSFX1CVZV0tFd6due5OR1juj oWKJF86+yF9fbF74NGTxzBXCOFbomeGjMA6CB0rHNt0M40gas2t2OStNtmCzTKvcgJXk ZpWp5ZRGpNUqrr2if115pJ0gik6N+Ra8ssyZpQpeE8Ogd8hpsTM+/4wBNMZLAuZ8tGDB VrCAxbkrAMse1xPLltCEBjHLLZKME16iI9FUGoMCq8keckGerD72HOaXE9/Wb0/v+kIc 9PWA== X-Forwarded-Encrypted: i=1; AJvYcCXR8BMPTZDzkf7hTSoMFNlsLY7NS8ejgdZIwrlqTtrlmAw/u5cSs2arcNAHxs7Eb+pGea3pTZMgm/FP@vger.kernel.org X-Gm-Message-State: AOJu0YyEfeU9b59/3F8B/uuy9HCQsYgaB5NIDuq55p+buoua9F6pH/TL 83Puh2bk5trpi1l1au9ls/mfe2DeAaoUpDslHw5knjfueGWAMviQVo5QflQERwJQlAomwiUqBU2 v X-Google-Smtp-Source: AGHT+IFz5XTr3EIROtIPpFoKHylvL1QdVJcWXNO7nykeyPKX/xmocaToBUHmUscO0mtRSXqS4prCDA== X-Received: by 2002:a05:6214:2e44:b0:6bf:79e5:b129 with SMTP id 6a1803df08f44-6c3554a7863mr160315666d6.49.1725465900182; Wed, 04 Sep 2024 09:05:00 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-68-80-239.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.80.239]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6c340c3a6a2sm64790326d6.58.2024.09.04.09.04.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2024 09:04:59 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1slsV8-004iPn-SJ; Wed, 04 Sep 2024 13:04:58 -0300 Date: Wed, 4 Sep 2024 13:04:58 -0300 From: Jason Gunthorpe To: Leon Romanovsky Cc: Junxian Huang , linux-rdma@vger.kernel.org, linuxarm@huawei.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 for-next 1/2] RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages Message-ID: <20240904160458.GB1909087@ziepe.ca> References: <20240828064605.887519-1-huangjunxian6@hisilicon.com> <20240828064605.887519-2-huangjunxian6@hisilicon.com> <20240902065726.GA4026@unreal> <20240903070922.GI4026@unreal> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240903070922.GI4026@unreal> On Tue, Sep 03, 2024 at 10:09:22AM +0300, Leon Romanovsky wrote: > > The original thought was that ib_uverbs_mmap() reads ufile->disassociated while > > uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried > > to use atomic_t to avoid racing without adding locks. > > atomic_t is never a replacement for locks. It is a way to provide > coherent view of the data between CPUs and makes sure that write/read is > not interrupted. Yes, add a lock, like I said Jason