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 DE4A1C48BEB for ; Wed, 14 Feb 2024 08:36:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 70A536B0095; Wed, 14 Feb 2024 03:36:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6BA5D6B0096; Wed, 14 Feb 2024 03:36:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5825A6B0098; Wed, 14 Feb 2024 03:36:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 3FE5A6B0095 for ; Wed, 14 Feb 2024 03:36:45 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id CD2F840D92 for ; Wed, 14 Feb 2024 08:36:44 +0000 (UTC) X-FDA: 81789753528.08.49C0834 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf14.hostedemail.com (Postfix) with ESMTP id 29C63100010 for ; Wed, 14 Feb 2024 08:36:42 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=bD1tbGyj; dmarc=none; spf=none (imf14.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 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1707899803; 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=ysgB/GGpyfayW7mHOvTqBQpAbr1V5Q1mXrOhN5+trOA=; b=dHhY8jMsSpd5HKBSllTaacwPH7O8BbVzf1pu2Lee6Bfa8ZbPiZ/LVaM0Wh5SPRt8uqX2H9 Hsz/u1RCgWD1qdRx7WKBvKq+tP+u1MRIag37TnSVjpfXy3SGoqRpAuN3Cs4NNotO4ME/te g9JfsM7um/IZ1D730FTa+hinTA0FopY= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=bD1tbGyj; dmarc=none; spf=none (imf14.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 ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1707899803; a=rsa-sha256; cv=none; b=jBoMjoYd5JtH28iDZrHQl/Ch47nDF+4CtDi6PU2K5sKtXB3R+xAmGlgE1NXN3Hl1qvOPY+ bC1PiT5WnanxnaJKZXPvyEiN/uoC01FGXcWHUfX8QJY3zlipffpbKhBfEWS6KKeaZSGW34 jEYf8iHe2Fx+ivG06QvhxirlSCd6qUo= 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=ysgB/GGpyfayW7mHOvTqBQpAbr1V5Q1mXrOhN5+trOA=; b=bD1tbGyjej0aP5XLpeVu6se911 aDrulCKCvfw0I1igpN6vIroKO/ldhvd4lgSAH09nzisa/jYFm2EW0ga7IlrcibKc6+D5d7PAtW5jX zQvJkVoOlfzT891jCFzG0/PjkTbozlM1egTfhigozVtl3h0S3axKS1LqJXm9+10hjA7f2x5M2kRQx G1RJlqqNEU5QCeremMtWP9hxoPhrjtQzOxC1vAe1eEnjrqc/qaUlIDLRDUCxdZXr92JUPpEmvNsAj nNqgWcCDXhoMjH+5SJlF7VDNqEkQlFfdmoSIoDEEM7d/h9D29fJb9hKfIyB/A+Fp3t4mdRWFckPAB n13h4doQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1raAkv-0000000C9yS-1xDL; Wed, 14 Feb 2024 08:36:37 +0000 Date: Wed, 14 Feb 2024 00:36:37 -0800 From: Christoph Hellwig To: Alexei Starovoitov Cc: bpf@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, memxor@gmail.com, eddyz87@gmail.com, tj@kernel.org, brho@google.com, hannes@cmpxchg.org, lstoakes@gmail.com, akpm@linux-foundation.org, urezki@gmail.com, hch@infradead.org, linux-mm@kvack.org, kernel-team@fb.com Subject: Re: [PATCH v2 bpf-next 04/20] mm: Expose vmap_pages_range() to the rest of the kernel. 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Please On Thu, Feb 08, 2024 at 08:05:52PM -0800, Alexei Starovoitov wrote: > From: Alexei Starovoitov > > BPF would like to use the vmap API to implement a lazily-populated > memory space which can be shared by multiple userspace threads. > The vmap API is generally public and has functions to request and What is "the vmap API"? > For example, there is the public ioremap_page_range(), which is used > to map device memory into addressable kernel space. It's not really public. It's a helper for the ioremap implementation which really should not be arch specific to start with and are in the process of beeing consolidatd into common code. > The new BPF code needs the functionality of vmap_pages_range() in > order to incrementally map privately managed arrays of pages into its > vmap area. Indeed this function used to be public, but became private > when usecases other than vmalloc happened to disappear. Yes, for a freaking good reason. The vmap area is not for general abuse by random callers. We have a few of those left, but we need to get rid of that and not add more.