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 X-Spam-Level: X-Spam-Status: No, score=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D78AFC2BC61 for ; Mon, 29 Oct 2018 02:30:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F65E2082D for ; Mon, 29 Oct 2018 02:30:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qoUpw6Jl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F65E2082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729163AbeJ2LRG (ORCPT ); Mon, 29 Oct 2018 07:17:06 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:37082 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729050AbeJ2LRG (ORCPT ); Mon, 29 Oct 2018 07:17:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=HgVFgci+gjDF7DF5bd6K2ongmaAjKrHaNK3ZkD4uZPQ=; b=qoUpw6JlTu2E46hzop7Msu8Sh UtVNFkbZ8aA92MtV4P6RKqq9F/JlYOPmHPzmkRflNhXX3MwkdBtJO6f25LpaMSqWVBvyVWYv2TZbC I6vbWI91pdjJalWv/Fe+N7pkquXDl3JZpZMeSrtVa2oAxSmm613tUtHny6UOQa/hsnkNYX9kyPVgA Hs6wo/cHOsfZwJi1wynKE0tYVXPwHxDJjWfbOx8LC7Vs/IHS2oVfb16DvmBc1H2RVsFl6nU2ITlez mAi9zO4RWwGZqntB9qMFAShH56uVVgfXyNkr0ZC0nk+052In7q7n9ayuhoxKDwceGpBIHVz8M38o0 hVTcecWiA==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gGxJz-0002ef-1T; Mon, 29 Oct 2018 02:30:27 +0000 Date: Sun, 28 Oct 2018 19:30:26 -0700 From: Matthew Wilcox To: miles.chen@mediatek.com Cc: Matthias Brugger , linux-kernel@vger.kernel.org, linux-mm@kvack.org, wsd_upstream@mediatek.com, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Joe Perches , Michal Hocko Subject: Re: [PATCHv2] mm/page_owner: use kvmalloc instead of kmalloc Message-ID: <20181029023026.GC28520@bombadil.infradead.org> References: <1540779403-27622-1-git-send-email-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1540779403-27622-1-git-send-email-miles.chen@mediatek.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 29, 2018 at 10:16:43AM +0800, miles.chen@mediatek.com wrote: > The kbuf used by page owner is allocated by kmalloc(), which means it > can use only normal memory and there might be a "out of memory" > issue when we're out of normal memory. > > Use kvmalloc() so we can also allocate kbuf from > normal/hihghmem on 32bit kernel. That's a misconception: ret = kmalloc_node(size, kmalloc_flags, node); /* * It doesn't really make sense to fallback to vmalloc for sub page * requests */ if (ret || size <= PAGE_SIZE) return ret; Now, maybe this is an opportunity for us to improve kvmalloc. Maybe like this ... diff --git a/mm/util.c b/mm/util.c index 8bf08b5b5760..fdf5b34d2c28 100644 --- a/mm/util.c +++ b/mm/util.c @@ -416,10 +416,10 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) ret = kmalloc_node(size, kmalloc_flags, node); /* - * It doesn't really make sense to fallback to vmalloc for sub page - * requests + * It only makes sense to fallback to vmalloc for sub page + * requests if we might be able to allocate highmem pages. */ - if (ret || size <= PAGE_SIZE) + if (ret || (!IS_ENABLED(CONFIG_HIGHMEM) && size <= PAGE_SIZE)) return ret; return __vmalloc_node_flags_caller(size, node, flags,