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=-9.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 70F75C388F7 for ; Thu, 5 Nov 2020 00:03:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11226207BB for ; Thu, 5 Nov 2020 00:03:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="my7fkLi5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387841AbgKEADp (ORCPT ); Wed, 4 Nov 2020 19:03:45 -0500 Received: from m42-4.mailgun.net ([69.72.42.4]:24722 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731343AbgKEADm (ORCPT ); Wed, 4 Nov 2020 19:03:42 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1604534621; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=+0WnlWc0h6ylWdn3v/K8WxY0ja4ryNOQxixoZcWIBvQ=; b=my7fkLi53OPPYtbr8pX7tldLgtAvUQs7U1HGA7jbH0RwJXAGo4JlhLlMBtSFv64d2yxV2Qki 2hC/4GPRVgTu8HFvOI9o7KIkrGJ4dtlgk1zGYy3Ytyz0GcQBwHN/swQ0Di1FXIiL2+6yPwbt xjPe7NRPVJMXl8L0/eHsD1OOpxU= X-Mailgun-Sending-Ip: 69.72.42.4 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-west-2.postgun.com with SMTP id 5fa3415c77d543c3c7c86714 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 05 Nov 2020 00:03:40 GMT Sender: sudaraja=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 363ACC43382; Thu, 5 Nov 2020 00:03:39 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sudaraja) by smtp.codeaurora.org (Postfix) with ESMTPSA id 52C2DC433FE; Thu, 5 Nov 2020 00:03:37 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 04 Nov 2020 16:03:36 -0800 From: Sudarshan Rajagopalan To: Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Gavin Shan , Anshuman Khandual , Mark Rutland , Logan Gunthorpe , David Hildenbrand , Andrew Morton , Steven Price Subject: Re: [PATCH v4] arm64/mm: add fallback option to allocate virtually contiguous memory In-Reply-To: References: Message-ID: <4ca1e695f81b368a5487bdaa9b421a95@codeaurora.org> X-Sender: sudaraja@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-10-16 11:56, Sudarshan Rajagopalan wrote: Hello Will, Catalin, Did you have a chance to review this patch? It is reviewed by others and haven't seen any Nacks. This patch will be useful to have so that memory hotremove doesn't fail when such PMD_SIZE pages aren't available.. which is usually the case in low RAM devices. > When section mappings are enabled, we allocate vmemmap pages from > physically continuous memory of size PMD_SIZE using > vmemmap_alloc_block_buf(). Section mappings are good to reduce TLB > pressure. But when system is highly fragmented and memory blocks are > being hot-added at runtime, its possible that such physically > continuous > memory allocations can fail. Rather than failing the memory hot-add > procedure, add a fallback option to allocate vmemmap pages from > discontinuous pages using vmemmap_populate_basepages(). > > Signed-off-by: Sudarshan Rajagopalan > Reviewed-by: Gavin Shan > Reviewed-by: Anshuman Khandual > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Anshuman Khandual > Cc: Mark Rutland > Cc: Logan Gunthorpe > Cc: David Hildenbrand > Cc: Andrew Morton > Cc: Steven Price > --- > arch/arm64/mm/mmu.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 75df62fea1b6..44486fd0e883 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1121,8 +1121,11 @@ int __meminit vmemmap_populate(unsigned long > start, unsigned long end, int node, > void *p = NULL; > > p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); > - if (!p) > - return -ENOMEM; > + if (!p) { > + if (vmemmap_populate_basepages(addr, next, node, altmap)) > + return -ENOMEM; > + continue; > + } > > pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); > } else -- Sudarshan -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project