From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 33B478F58 for ; Wed, 30 Oct 2024 04:33:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730262810; cv=none; b=c3Ymr+DtyX8v41VmlpiAyiSkU3CKdtUs8Q3KJ3Q9uqlK5ZkXqmBChYSOE3sfEHelLKxyOXL5SAeCP0ZwFZET9iBOSD6/dzTuQHd/Xhd+df3SBI1/EhdALUkx6VNafnOL+76TojI4/2BwGR3Voh5s8FLErz/xZwUcvyfQY3MfG1U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730262810; c=relaxed/simple; bh=7MYoUADX/p3i4JXe76Yp7utNi3GSHnJGT3PZCpfrgp4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=A7Mwbf3NTdGa9t9EpPLXwzFwMf5Kpx0aJkklgvva+ZdV3QXD20v9PN2wqVbphxXRBYmY6Ard4mLfqc6+0dGTWmQKQbQhu9P/sGaw2gIFDVBIuS5FCn0yOz3ILKydWTpcO8I85igZk+7NImsqrqFWxfqfOH/e2gt6TTphkedvQJU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=nJ8yYR0Y; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nJ8yYR0Y" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ztXonWeHlXSXD26VwgY5O/UQHUJOn+ojrlIUafH4x58=; b=nJ8yYR0YAQvy5Q1/oFYfUYBHRX LI6EO3DygMTZ4Ktsi7bT+fG0e6tsgrMhy2DXxVsRpjogDkK6iMPvTmeqE6UoJ/yvbKJAMhQHUI/H8 9c4voPJL2sH6jDHp904ZI4p3gsp5/f4Z6uuK/d1CmpDtQhA9ClBytDfYGvenXD5CUi2hFT1MNJW2u nFyqI2cwHvox0nWl8Fhc0CUhQavFiwio0RAR8zI8yXP6G41RlLL646RvhewYWfThQgJBp90y8sXfT Z9PMvrlQeAMsbwfflWvT/nebKgIxMe1uYfuODkPhiWWh0p+CzDMRhKt0tGuaiISB3aF7p8yf1s8ni by1OL8qg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1t60Oe-0000000Gg1Q-1E7V; Wed, 30 Oct 2024 04:33:28 +0000 Date: Tue, 29 Oct 2024 21:33:28 -0700 From: Christoph Hellwig To: John Hubbard Cc: Christoph Hellwig , Andrew Morton , LKML , linux-mm@kvack.org, linux-stable@vger.kernel.org, Vivek Kasireddy , David Hildenbrand , Dave Airlie , Gerd Hoffmann , Matthew Wilcox , Jason Gunthorpe , Peter Xu , Arnd Bergmann , Daniel Vetter , Dongwon Kim , Hugh Dickins , Junxiao Chang , Mike Kravetz , Oscar Salvador Subject: Re: [PATCH] mm/gup: restore the ability to pin more than 2GB at a time Message-ID: References: <20241030030116.670307-1-jhubbard@nvidia.com> <249d2614-0bcc-4ca8-b24e-7c0578a81dce@nvidia.com> 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=us-ascii Content-Disposition: inline In-Reply-To: <249d2614-0bcc-4ca8-b24e-7c0578a81dce@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Oct 29, 2024 at 09:30:41PM -0700, John Hubbard wrote: > I do, yes. And what happens is that when you use GPUs, drivers like > to pin system memory, and then point the GPU page tables to that > memory. For older GPUs that don't support replayable page faults, > that's required. > > So this behavior has been around forever. > > The customer was qualifying their software and noticed that before > Linux 6.10, they could allocate >2GB, and with 6.11, they could > not. > > Whether it is "wise" for user space to allocate that much at once > is a reasonable question, but at least one place is (or was!) doing > it. Still missing a callchain, which make me suspect that it is your weird out of tree driver, in which case this simply does not matter.