From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f170.google.com (mail-qk1-f170.google.com [209.85.222.170]) (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 8BE7D274FDF for ; Tue, 6 Jan 2026 01:07:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767661633; cv=none; b=LLLf3nPJQamt7/MI8FHT40aQg7T4pJsuuqmdzM3/ASq3fPXLWp8smPP1oVFlYfaLoW3BycdIFULex8lvjMKuYYfg1Vl7ARAskR1G/N72SiwIl9fco0y1dfMLZc4po6J/Oq5BM0bK6v0RwJB7IHDCb+Y+qHQ4pjkrJmz75whCIU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767661633; c=relaxed/simple; bh=TtpdHbukwEFQnmz3ckdmLHSJzLrBUAxVPaYrmXbSQQs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=j+jcJTgQ4LIa9pdTwkQpjQAPECvhN1GlRlCIYhTUTyBL8lR2Cy4vT4WrPX2MRglpSFJXp+9ZlZxzOL6Zjd0SFDonVzRbcfQe5U89BMr6oUDySIUzd6Tfn7zNDSUTEJMklVzRMQ04faUutn9JzAiMDtPM0+1gBeeLZajyIHD+x6c= 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=WAdXLdY+; arc=none smtp.client-ip=209.85.222.170 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="WAdXLdY+" Received: by mail-qk1-f170.google.com with SMTP id af79cd13be357-8ba0d6c68a8so47226585a.1 for ; Mon, 05 Jan 2026 17:07:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1767661630; x=1768266430; 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=drgdDcwNGsxFqgCONrNiAAW6lMSwQ04qtIUzzps58Z0=; b=WAdXLdY+xsEq2Bwew26X6rHqoYm3Pt7kjVpfN05xaN7KMcpaCSc/24JwE0MlDhyfRa kxby86ilhfrQcBEGcsS8eU0htnXqV+EDYYpgh5ppHUOQvPv9YdCOZ73qHSDDVQRfYDLu jU1Yn96W1X6YUmjgrL1pGRLS5Lc9CV38EATlORx1kN3PvpHTl/cwXS/YSZoBdTVvGEpM EQw4SDeQx0p7wVDlCJPx+4/hfrLPoq/rF76S5rg1KN6USUyV6C7ZTsO5zlxN5U/6ABNZ f8TFLiKRddC51Oh34ebZauDsvFdtBDGpyjbbjvzWQcP4U9IKk47Yl7/OAG/YDV2Z2TP5 AVQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767661630; x=1768266430; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=drgdDcwNGsxFqgCONrNiAAW6lMSwQ04qtIUzzps58Z0=; b=Z8BqKuvv+KhrOmTeLzVibNlPuaTgzHcKc/3kbhZbd+KDLLyBgro9T4EywAkuNIRNbW gv5vVardjj9/3NXMkSKHGME4O+xLhYyB1OppFobonwCxA6TevY53iVDZ/6rdPCS6QQLQ wMR87kWpHaL3jxIPRfW0Iy4czElb6JT0F6msIM0Q67R34tvGyUJrQ1wToIG1UGtcN2Jy CfsyySU8V4jT3iETjNlJsZjON79UoznVNUWXdSP1vwG7gET6bLcPO0R8UDP0kgoxGb9M 5A5WxZL+UgWgy432rdIztCNVQAeR43Wy1gCIlKHIvn/ePTyVqBu71EXXDne4KkHfzkwe 1+fw== X-Gm-Message-State: AOJu0YxaoUs/rUrvFHuskCuW9t3fwexwzyoZE19kCQI+nNZvPtVzDzp6 0H2VnQzRhxf2LNLznaIzO0w+qV34AphzSwHkvY9P9XZ2uJd8XGhbKH4a/CkEjoQsmKM= X-Gm-Gg: AY/fxX7ScfxtvPtQhsTTZuVL4FhGgVVHtBsx/D+3+bGmsn1hIpz8oSQzRs68NhlRi/8 4emPXefF9Zzjw8VsxcQV7ia5TLcTY1BcD9J3EIMcshD5lRKFavUsLDofSLIeITYdZ23gOxYV/V4 U3DS0KUTXV7tKCCeemZGdLMveVKLYOTTNHixRyq8bFbdv+2GCS6E/G0YmGl0g7XsFVyr0XrR2Rd DlHerqjvYu2ZBNEaP736C8tgZBmZddLgxpNjJE5gO/pN78e2ohfDdIAo7MN2uCiNgKZRFTN46yB 21QIV0B2PAkKKbNblvsQU3PNOb83JKZwv9+FpNNgAUOTH392TMQUEAHyuPb+feGu31qgau+1tNJ YYX+iY1ACLXeAUWZ06uCv4hvq3cMN9ZOMut3YyL+T981o4l6YEGayXUIEeEfuY4NE0LnEAqJLww sfw6Omm8nECTEg/VHqV3Azq5p7ESrHulgBdbALormtQacjVRzwNrogNSU+81cTU0T/09w/g1jpn jMq8w== X-Google-Smtp-Source: AGHT+IHhT1NOnu42pNSz12y0NefP0H/0F1k0TtCk86h7IFq9pIdlZ9qXpmEGoKQZYUBTJdVBDiNU1A== X-Received: by 2002:a05:620a:708b:b0:8c2:2b5c:6bb3 with SMTP id af79cd13be357-8c37ec03772mr174404885a.85.1767661630435; Mon, 05 Jan 2026 17:07:10 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-112-119.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.112.119]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c37f4a97fesm67018585a.4.2026.01.05.17.07.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jan 2026 17:07:09 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vcvXR-00000001Eb9-164U; Mon, 05 Jan 2026 21:07:09 -0400 Date: Mon, 5 Jan 2026 21:07:09 -0400 From: Jason Gunthorpe To: "Zhijian Li (Fujitsu)" Cc: "linux-rdma@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "zyjzyj2000@gmail.com" , "leon@kernel.org" , Yi Zhang , Bob Pearson Subject: Re: [PATCH RFC] rxe: Fix iova-to-va conversion for MR page sizes != PAGE_SIZE Message-ID: <20260106010709.GO125261@ziepe.ca> References: <20251226095237.3047496-1-lizhijian@fujitsu.com> 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: On Mon, Jan 05, 2026 at 06:55:22AM +0000, Zhijian Li (Fujitsu) wrote: > After digging into the behavior during the srp/012 test again, it > turns out this fix is incomplete. The current xarray page_list > approach cannot correctly map memory regions composed of two or more > scatter-gather segments. I seem to recall there are DMA API functions that can control what kinds of scatterlists the block stack will push down. For real HW we already cannot support less than 4K alignment of interior SGL segments. Maybe rxe can tell the block stack it can only support PAGE_SIZE alignment of interior SGL segments? If not then this would be the reason rxe needs mr->page_size, to support 4k. And obviously if the mr->page size is less than PAGE_SIZE the xarray datastructure does not work. You'd have to store physical addresses instead.. Jason