From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 57B246B0358 for ; Sun, 28 Oct 2018 22:30:31 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id v88-v6so6400603pfk.19 for ; Sun, 28 Oct 2018 19:30:31 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id f88-v6si19641334pfe.243.2018.10.28.19.30.30 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 28 Oct 2018 19:30:30 -0700 (PDT) Date: Sun, 28 Oct 2018 19:30:26 -0700 From: Matthew Wilcox 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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,