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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 25EA4C43141 for ; Fri, 15 Nov 2019 23:55:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D99C42073C for ; Fri, 15 Nov 2019 23:55:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KGWeGLil" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D99C42073C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 708AB6B0005; Fri, 15 Nov 2019 18:55:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 692006B0006; Fri, 15 Nov 2019 18:55:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 559D46B0007; Fri, 15 Nov 2019 18:55:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id 4719A6B0005 for ; Fri, 15 Nov 2019 18:55:38 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 23F84585D for ; Fri, 15 Nov 2019 23:55:38 +0000 (UTC) X-FDA: 76160171556.02.quilt61_14053e7e39e19 X-HE-Tag: quilt61_14053e7e39e19 X-Filterd-Recvd-Size: 5025 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Fri, 15 Nov 2019 23:55:37 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2749B2073B; Fri, 15 Nov 2019 23:55:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573862136; bh=AYrhLwNe+hXbVspP++qlUMNb9xKXjMVWzMPNNDOYrIg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KGWeGLilG3+3DKI5HLLGVAe12sNQYLZGW85uj4Wy3mPN1wLkBJL5YBcvmro0PhG42 +eLH4jm8MxT4zeQ/s14zlAmZltszkv15zw9kOMTEbP0etbzNKR0/eaZUuWYA/qi43G zbsGmD4WwNqV6H/yPV4gWvTyJBA2AflAG6ncj/Rc= Date: Fri, 15 Nov 2019 15:55:35 -0800 From: Andrew Morton To: Michal Hocko Cc: Vincent Whitchurch , Pavel Tatashin , "osalvador@suse.de" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm/sparse: Consistently do not zero memmap Message-Id: <20191115155535.2a9da68ad58bb787a0ac7833@linux-foundation.org> In-Reply-To: <20191105084352.GJ22672@dhcp22.suse.cz> References: <20191030131122.8256-1-vincent.whitchurch@axis.com> <20191030132958.GD31513@dhcp22.suse.cz> <20191030140216.i26n22asgafckfxy@axis.com> <20191030141259.GE31513@dhcp22.suse.cz> <20191030153150.GI31513@dhcp22.suse.cz> <20191030173123.GK31513@dhcp22.suse.cz> <20191031072555.GA13102@dhcp22.suse.cz> <20191104155126.y2fcjwrx5mhdoqi7@axis.com> <20191105084352.GJ22672@dhcp22.suse.cz> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 Tue, 5 Nov 2019 09:43:52 +0100 Michal Hocko wrote: > On Mon 04-11-19 16:51:26, Vincent Whitchurch wrote: > > On Thu, Oct 31, 2019 at 08:25:55AM +0100, Michal Hocko wrote: > > > On Wed 30-10-19 18:31:23, Michal Hocko wrote: > > > [...] > > > > What about this? It still aligns to the size but that should be > > > > correctly done to the section size level. > > > > > > > > diff --git a/mm/sparse.c b/mm/sparse.c > > > > index 72f010d9bff5..ab1e6175ac9a 100644 > > > > --- a/mm/sparse.c > > > > +++ b/mm/sparse.c > > > > @@ -456,8 +456,7 @@ struct page __init *__populate_section_memmap(unsigned long pfn, > > > > if (map) > > > > return map; > > > > > > > > - map = memblock_alloc_try_nid(size, > > > > - PAGE_SIZE, addr, > > > > + map = memblock_alloc_try_nid(size, size, addr, > > > > MEMBLOCK_ALLOC_ACCESSIBLE, nid); > > > > if (!map) > > > > panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n", > > > > @@ -474,8 +473,13 @@ static void __init sparse_buffer_init(unsigned long size, int nid) > > > > { > > > > phys_addr_t addr = __pa(MAX_DMA_ADDRESS); > > > > WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */ > > > > + /* > > > > + * Pre-allocated buffer is mainly used by __populate_section_memmap > > > > + * and we want it to be properly aligned to the section size - this is > > > > + * especially the case for VMEMMAP which maps memmap to PMDs > > > > + */ > > > > sparsemap_buf = > > > > - memblock_alloc_try_nid_raw(size, PAGE_SIZE, > > > > + memblock_alloc_try_nid_raw(size, section_map_size(), > > > > addr, > > > > MEMBLOCK_ALLOC_ACCESSIBLE, nid); > > > > sparsemap_buf_end = sparsemap_buf + size; > > > > > > Vincent, could you give this a try please? It would be even better if > > > you could add some debugging to measure the overhead. Let me know if you > > > need any help with a debugging patch. > > > > I've tested this patch and it works on my platform: The allocations > > from sparse_buffer_alloc() now succeed and the fallback path is not > > taken. > > Thanks a lot. I will try to prepare the full patch with a proper > changelog sometimes this week. > We're late in -rc7. Should we run with Vincent's original for now? And I'm wondering why this is -stable -material? You said : Anyway the patch is OK. Even though this is not a bug strictly : speaking it is certainly a suboptimal behavior because zeroying takes : time so I would flag this for a stable tree 4.19+. There is no clear : Fixes tag to apply (35fd1eb1e8212 would get closest I guess). I'm not seeing any description of any runtime effect of the bug at present. When would unzeroed sparsemem pageframes cause a problem? Could they be visible during deferred initialization or mem hotadd?