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 2C470C433EF for ; Sat, 9 Apr 2022 05:28:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7E8416B0071; Sat, 9 Apr 2022 01:28:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 77B6C6B0073; Sat, 9 Apr 2022 01:28:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65E9F6B0074; Sat, 9 Apr 2022 01:28:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 543F86B0071 for ; Sat, 9 Apr 2022 01:28:15 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 06FA318404064 for ; Sat, 9 Apr 2022 05:28:15 +0000 (UTC) X-FDA: 79336209750.25.4A842A3 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf19.hostedemail.com (Postfix) with ESMTP id 80F7A1A0002 for ; Sat, 9 Apr 2022 05:28:14 +0000 (UTC) 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=UELACyVvvsv7I05n9+vrbyhbff2QK+RQVjTLcZ7BmLg=; b=yjRyUNNZJ+QcVl6cC7NuMHkkWo s0/WGg7fW8quqrK5WTwAxvCspJlWPhWh44WOnhXrUs6Xj9sc4KmSWjbFQvLmqLuDYlrXkfni5q9nc IX7lbqve87N0Wlia2y6UmXmDfnF5/aZ7W2DmAvELSS1I7W6UMjD9Aii0ET81eszLt80eQMGz0VPKT 0X715mDCiAtLZFok6yq8NE1kX7ORTM2aySTyp6Zg6sy59MUm61MITFQ4DlOmrpEA0nW8A9e0Q+m/W Nq7p0DjvUlc6TBotYnplOKXKIBP7sIzbqgKKmC/PooxRmDPdope8lHBakiuly2QhtoUedRmzaSmiG ZNKutwGA==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nd3dq-002IuG-Ht; Sat, 09 Apr 2022 05:28:10 +0000 Date: Fri, 8 Apr 2022 22:28:10 -0700 From: Christoph Hellwig To: Song Liu Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kernel-team@fb.com, akpm@linux-foundation.org, rick.p.edgecombe@intel.com, hch@infradead.org, imbrenda@linux.ibm.com Subject: Re: [PATCH bpf 1/2] vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLOW_HUGE_VMAP Message-ID: References: <20220408223443.3303509-1-song@kernel.org> <20220408223443.3303509-2-song@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220408223443.3303509-2-song@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspam-User: X-Stat-Signature: 6qc6bxjura4ha89gyjht96xbwonq6boz Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=yjRyUNNZ; spf=none (imf19.hostedemail.com: domain of BATV+43fc5532e856fea764d1+6803+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+43fc5532e856fea764d1+6803+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 80F7A1A0002 X-HE-Tag: 1649482094-177645 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: On Fri, Apr 08, 2022 at 03:34:42PM -0700, Song Liu wrote: > Huge page backed vmalloc memory could benefit performance in many cases. > Since some users of vmalloc may not be ready to handle huge pages, > VM_NO_HUGE_VMAP was introduced to allow vmalloc users to opt-out huge > pages. However, it is not easy to add VM_NO_HUGE_VMAP to all the users > that may try to allocate >= PMD_SIZE pages, but are not ready to handle > huge pages properly. > > Replace VM_NO_HUGE_VMAP with an opt-in flag, VM_ALLOW_HUGE_VMAP, so that > users that benefit from huge pages could ask specificially. Given that the huge page backing was added explicitly for some big boot time allocated hashed,those should probably have the VM_ALLOW_HUGE_VMAP added from the start (maybe not in this patch, but certainly in this series). We'll probably also need a vmalloc_huge interface for those.