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,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 4A35BC432C3 for ; Sun, 1 Dec 2019 01:54:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0C07220880 for ; Sun, 1 Dec 2019 01:54:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HdzMEFIe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C07220880 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 ADA136B0303; Sat, 30 Nov 2019 20:54:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A897F6B0305; Sat, 30 Nov 2019 20:54:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9C7D76B0306; Sat, 30 Nov 2019 20:54:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0131.hostedemail.com [216.40.44.131]) by kanga.kvack.org (Postfix) with ESMTP id 8768E6B0303 for ; Sat, 30 Nov 2019 20:54:29 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 3FB1A180AD817 for ; Sun, 1 Dec 2019 01:54:29 +0000 (UTC) X-FDA: 76214903058.05.sand27_272229111323b X-HE-Tag: sand27_272229111323b X-Filterd-Recvd-Size: 4280 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Sun, 1 Dec 2019 01:54:28 +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 D4BD221774; Sun, 1 Dec 2019 01:54:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575165268; bh=fAREv1unVnWXEyDlXNS++09m8uVAdR/fTkl6IrPJae8=; h=Date:From:To:Subject:From; b=HdzMEFIeYZHahnFcsFhh9E1grVXIFidv6ER6naunVHcp3OoUfkw9aV23WTtqS8HGd sCpkyuAfFy/eY6DdVX+XjFddpqUxmGP3URiMPVh1L40uhDrpGCGCvYSQWeJBd1yvsI TNgDwMjUFF1IxreVIQybNFQoXgrmqNERNOw8NwjY= Date: Sat, 30 Nov 2019 17:54:27 -0800 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, OSalvador@suse.com, pasha.tatashin@soleen.com, torvalds@linux-foundation.org, vincent.whitchurch@axis.com Subject: [patch 086/158] mm/sparse.c: do not waste pre allocated memmap space Message-ID: <20191201015427.E9NNqefxs%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Michal Hocko Subject: mm/sparse.c: do not waste pre allocated memmap space Vincent has noticed [1] that there is something unusual with the memmap allocations going on on his platform : I noticed this because on my ARM64 platform, with 1 GiB of memory the : first [and only] section is allocated from the zeroing path while with : 2 GiB of memory the first 1 GiB section is allocated from the : non-zeroing path. The underlying problem is that although sparse_buffer_init allocates enough memory for all sections on the node sparse_buffer_alloc is not able to consume them due to mismatch in the expected allocation alignement. While sparse_buffer_init preallocation uses the PAGE_SIZE alignment the real memmap has to be aligned to section_map_size() this results in a wasted initial chunk of the preallocated memmap and unnecessary fallback allocation for a section. While we are at it also change __populate_section_memmap to align to the requested size because at least VMEMMAP has constrains to have memmap properly aligned. [1] http://lkml.kernel.org/r/20191030131122.8256-1-vincent.whitchurch@axis.com [akpm@linux-foundation.org: tweak layout, per David] Link: http://lkml.kernel.org/r/20191119092642.31799-1-mhocko@kernel.org Fixes: 35fd1eb1e821 ("mm/sparse: abstract sparse buffer allocations") Signed-off-by: Michal Hocko Reported-by: Vincent Whitchurch Debugged-by: Vincent Whitchurch Acked-by: David Hildenbrand Cc: Pavel Tatashin Cc: Oscar Salvador Signed-off-by: Andrew Morton --- mm/sparse.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/mm/sparse.c~mm-sparse-do-not-waste-pre-allocated-memmap-space +++ a/mm/sparse.c @@ -458,8 +458,7 @@ struct page __init *__populate_section_m if (map) return map; - map = memblock_alloc_try_nid_raw(size, - PAGE_SIZE, addr, + map = memblock_alloc_try_nid_raw(size, size, addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid); if (!map) panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n", @@ -482,10 +481,13 @@ static void __init sparse_buffer_init(un { phys_addr_t addr = __pa(MAX_DMA_ADDRESS); WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */ - sparsemap_buf = - memblock_alloc_try_nid_raw(size, PAGE_SIZE, - addr, - MEMBLOCK_ALLOC_ACCESSIBLE, nid); + /* + * 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, section_map_size(), + addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid); sparsemap_buf_end = sparsemap_buf + size; } _