From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug.patch added to -mm tree Date: Thu, 12 Mar 2020 16:41:21 -0700 Message-ID: <20200312234121.RhETSbTWK%akpm@linux-foundation.org> References: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:46702 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726608AbgCLXlX (ORCPT ); Thu, 12 Mar 2020 19:41:23 -0400 In-Reply-To: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: bhe@redhat.com, dan.j.williams@intel.com, david@redhat.com, mhocko@suse.com, mm-commits@vger.kernel.org, pankaj.gupta.linux@gmail.com, richard.weiyang@gmail.com The patch titled Subject: mm/sparse.c: add note about only VMEMMAP supporting sub-section hotplug has been added to the -mm tree. Its filename is mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Baoquan He Subject: mm/sparse.c: add note about only VMEMMAP supporting sub-section hotplug And tell check_pfn_span() gating the porper alignment and size of hot added memory region. And also move the code comments from inside section_deactivate() to being above it. The code comments are reasonable for the whole function, and the moving makes code cleaner. Link: http://lkml.kernel.org/r/20200312124414.439-5-bhe@redhat.com Signed-off-by: Baoquan He Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Cc: Dan Williams Cc: Pankaj Gupta Cc: Wei Yang Signed-off-by: Andrew Morton --- mm/sparse.c | 38 +++++++++++++++++++++----------------- 1 file changed, 21 insertions(+), 17 deletions(-) --- a/mm/sparse.c~mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug +++ a/mm/sparse.c @@ -750,6 +750,22 @@ static bool is_subsection_map_empty(stru } #endif +/* + * To deactivate a memory region, there are 3 cases to handle across + * two configurations (SPARSEMEM_VMEMMAP={y,n}): + * + * 1. deactivation of a partial hot-added section (only possible in + * the SPARSEMEM_VMEMMAP=y case). + * a) section was present at memory init. + * b) section was hot-added post memory init. + * 2. deactivation of a complete hot-added section. + * 3. deactivation of a complete section from memory init. + * + * For 1, when subsection_map does not empty we will not be freeing the + * usage map, but still need to free the vmemmap range. + * + * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified + */ static void section_deactivate(unsigned long pfn, unsigned long nr_pages, struct vmem_altmap *altmap) { @@ -760,23 +776,7 @@ static void section_deactivate(unsigned if (clear_subsection_map(pfn, nr_pages)) return; - /* - * There are 3 cases to handle across two configurations - * (SPARSEMEM_VMEMMAP={y,n}): - * - * 1/ deactivation of a partial hot-added section (only possible - * in the SPARSEMEM_VMEMMAP=y case). - * a/ section was present at memory init - * b/ section was hot-added post memory init - * 2/ deactivation of a complete hot-added section - * 3/ deactivation of a complete section from memory init - * - * For 1/, when subsection_map does not empty we will not be - * freeing the usage map, but still need to free the vmemmap - * range. - * - * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified - */ + empty = is_subsection_map_empty(ms); if (empty) { unsigned long section_nr = pfn_to_section_nr(pfn); @@ -884,6 +884,10 @@ static struct page * __meminit section_a * * This is only intended for hotplug. * + * Note that only VMEMMAP supports sub-section aligned hotplug, + * the proper alignment and size are gated by check_pfn_span(). + * + * * Return: * * 0 - On success. * * -EEXIST - Section has been present. _ Patches currently in -mm which might be from bhe@redhat.com are mm-hotplug-fix-hot-remove-failure-in-sparsememvmemmap-case.patch mm-sparsec-use-kvmalloc_node-kvfree-to-alloc-free-memmap-for-the-classic-sparse.patch mm-hotplug-only-respect-mem=-parameter-during-boot-stage.patch mm-sparsec-introduce-new-function-fill_subsection_map.patch mm-sparsec-introduce-a-new-function-clear_subsection_map.patch mm-sparsec-only-use-subsection-map-in-vmemmap-case.patch mm-sparsec-add-note-about-only-vmemmap-supporting-sub-section-hotplug.patch mm-sparsec-move-subsection_map-related-functions-together.patch