From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEE86C48BEB for ; Wed, 14 Feb 2024 08:31:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 50E878D0013; Wed, 14 Feb 2024 03:31:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4961E8D0001; Wed, 14 Feb 2024 03:31:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2E86C8D0013; Wed, 14 Feb 2024 03:31:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 19DB78D0001 for ; Wed, 14 Feb 2024 03:31:23 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 9EA5AC06AE for ; Wed, 14 Feb 2024 08:31:22 +0000 (UTC) X-FDA: 81789740004.29.02F27AE Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf18.hostedemail.com (Postfix) with ESMTP id 0A7F51C0007 for ; Wed, 14 Feb 2024 08:31:18 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ia2Ojjg9; spf=none (imf18.hostedemail.com: domain of BATV+637a42b34fbd5d460331+7479+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+637a42b34fbd5d460331+7479+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1707899481; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=IRQIBozged261rwkkkVGGiVN1CesemYgoVID/Sc+Mrs=; b=mis6lIcBzOR46dBYgVXeOlQ8Fx4Av9MXJv7+F/N/ci4+UB2CnPKzKwSORWvoXaSZS3Mz6h DuTxKxfUp0lM+xTeEnBLWXrw8F2RPTh2FEw4nRN2qo40lt3+0GkF6mmNIhjZE782ErpYD9 1mwrh3ljtu2P8JXejW8a4V4/Ib8nehs= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1707899481; a=rsa-sha256; cv=none; b=j4sNFWGPttTiGhZF1+LneaCG+4I03TneYl2tBtOTwk0bxVPQxI6Bub58m/lm2A5jpoABr+ /4H9yZ+ARibKC3FzkQO4zB9b0jBB7ycW7QE9fwliipYSYWCN2qKFzo1HbA3sdEcNigU9oa KNRvE+3rRBy8dOV5t7bUivhrK/nT4f0= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=ia2Ojjg9; spf=none (imf18.hostedemail.com: domain of BATV+637a42b34fbd5d460331+7479+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+637a42b34fbd5d460331+7479+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none 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=IRQIBozged261rwkkkVGGiVN1CesemYgoVID/Sc+Mrs=; b=ia2Ojjg9yxaVw4MvxwuyvgCz49 OhaNuu708nBZziRYAC2QrpbzKhhfp7btsCyzBMWbg12MPenSWhWt5ZS8luEeq/rmgaMtJqa52JKZl ZOr+cdSJR10/Lt0Epbkrj/tA+XU7VWant/+ymOOaKB7sOMMvUW78YC9tGoTRRBdve5TXPKV0APpJb NjgVCLWTJNhHm7k8EptFLJH/EVXXv6FCARrN45lgvX8EkP6K1jmAUUy1NvuSp2wSz/u26tqLB8Wv5 WvhuZ+cyU0w51LoPfal3BIX8Kag5jukofH4PzlDudw78XfhDYecy36hUsE/XPQFw5rVOcMNoX8OVf aBKGjGcg==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1raAfh-0000000C9Um-1zn5; Wed, 14 Feb 2024 08:31:13 +0000 Date: Wed, 14 Feb 2024 00:31:13 -0800 From: Christoph Hellwig To: Lorenzo Stoakes Cc: Alexei Starovoitov , bpf@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, memxor@gmail.com, eddyz87@gmail.com, tj@kernel.org, brho@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, kernel-team@fb.com, Andrew Morton , Uladzislau Rezki , Christoph Hellwig Subject: Re: [PATCH bpf-next 03/16] mm: Expose vmap_pages_range() to the rest of the kernel. Message-ID: References: <20240206220441.38311-1-alexei.starovoitov@gmail.com> <20240206220441.38311-4-alexei.starovoitov@gmail.com> <30a722f3-dbf5-4fa3-9079-6574aae4b81d@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <30a722f3-dbf5-4fa3-9079-6574aae4b81d@lucifer.local> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: 0A7F51C0007 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: mbjq4hkbedx8b8psh5po8kwn1rxarskd X-HE-Tag: 1707899478-230376 X-HE-Meta: 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 Rm2C8MYM 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Feb 07, 2024 at 09:07:51PM +0000, Lorenzo Stoakes wrote: > > memory region between bpf program and user space process. > > It will function similar to vmalloc()/vm_map_ram(): > > - get_vm_area() > > - alloc_pages() > > - vmap_pages_range() > > This tells me absolutely nothing about why it is justified to expose this > internal interface. You need to put more explanation here along the lines > of 'we had no other means of achieving what we needed from vmalloc because > X, Y, Z and are absolutely convinced it poses no risk of breaking anything'. > > I mean I see a lot of checks in vmap() that aren't in vmap_pages_range() > for instance. We good to expose that, not only for you but for any other > core kernel users? And as someone who has reviewed these same thing before: hard NAK. We need to keep vmalloc internals internal and not start poking holes into the abstractions after we've got them roughly into shape.